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HomeMy WebLinkAbout04/06/1995cit'19 / e0w CO3t,VnCI./ AGENDA Thursday, April 6, 1995 6:30 P.M. Joint Meeting with Planning Commission South Coast Air Quality Management District Auditorium 21865 East Copley Drive Diamond Bar, California Mayor Mayor Pro Tem Council Member Council Member Council Member City Manager City Attorney City Clerk Phyllis E. Papen Gary H. Werner Eileen R. Ansari Clair W. Harmony Gary G. Miller Terrence L. Belanger Michael Jenkins Lynda Burgess Copies of staff reports, or other written documentation relating to agenda items, are on file in the Office of the City Clerk, and are available for public inspection. If you have questions regarding an agenda item, please contact the City Clerk at (909) 860-2489 during regular business hours. In an effort to comply with the requirements of Title H of the Americans with Disabilities Act of 1990, the City of Diamond Bar requires that any person in need of any type of special equipment, assistance or accommodation(s) in order to communicate at a City public meeting, must inform the City Clerk a minimum of 72 hours prior to the scheduled meeting. Please refrain from smoking, eating or drinking ` r The City of Diamond Bar uses recycled paper in the Council Chambers., . - .. and encourages you to do the same. 1. 2. CALL TO ORDER: PLEDGE OF ALLEGIANCE: ROLL CALL: PLANNING COMMISSIONERS: OLD BUSINESS: Next Resolution No. 95-19 Next Ordinance No. 04(1995) 6:30 p.m. Mayor Papen April 6, 1995 Council Members Ansari, Harmony, Miller, Mayor Pro Tem Werner and Mayor Papen. Fong, Meyer, Schad, Vice -Chairman Robert Huff and Chairman Flamenbaum. 2.1 CERTIFICATION OF MASTER ENVIRONMENTAL IMPACT REPORT NO. 91-2 AND APPROVAL OF VESTING TENTATIVE TRACT MAP NO. 47850, LOCATED EASTERLY OF STEEPLECHASE LANE AND SOUTH OF WINDMILL DR. ADJACENT TO THE PRIVATE GATED COMMUNITY KNOWN AS "THE COUNTRY" - The vesting tentative map proposes the subdivision of 73 acres into 57 single family residential lots and one common lot with a private looped street system accentuated with four cul-de-sacs. Proposed lots range in size from .43 acres to 5.65 acres in size. The map has been recommended for approval by the Planning Commission with conditions. Recommended Action: It is recommended that the City Council open the Public Hearing, open the Joint Session with the Planning Commission, receive a presentation on the proposed development from staff and the applicant, receive public testimony, close the Public Hearing, and receive Planning Commission comments. Thereafter, it is recommended that the City Council continue deliberation and direct staff appropriately. Requested by: Community Development Director 3. ANNOUNCEMENTS: 4. ADJOURNMENT: DIAMOND BAR CITY COUNCIL MEETING RULES PUBLIC INPUT The meetings of the Diamond Bar City Council are open to the public. A member of the public may address the Council on the subject of one or more agenda items and/or other items of which are within the subject matter jurisdiction of the Diamond Bar City Council. A request to address the Council should be submitted in writing to the City Clerk. As a general rule the opportunity for public comments will take place at the discretion of the Chair. However, in order to facilitate the meeting, persons who are interested parties for an item may be requested to give their presentation at the time the item is called on the calendar. The Chair may limit the public input on any item or the total amount of time allocated for public testimony based on the number of people requesting to speak and the business of the Council. Individuals are requested to refrain from personal attacks toward Council Members or other persons. Comments which are not conducive to a positive business meeting environment are viewed as attacks against the entire City Council and will not be tolerated. If not complied with, you will forfeit your remaining time as ordered by the Chair. Your cooperation is greatly appreciated. In accordance with Government Code Section 54954.3(a) the Chair may from time to time dispense with public comment on items previously considered by the Council. (Does not apply to Committee meetings.) In accordance with State Law (Brown Act), all matters to be acted on by the City Council must be posted at least 72 hours prior to the Council meeting. In case of emergency or when a subject matter arises subsequent to the posting of the agenda, upon making certain findings, the Council may act on an item that is not on the posted agenda. CONDUCT IN THE CITY COUNCIL CHAMBERS The Chair shall order removed from the Council Chambers any person who commits the following acts in respect to a regular or special meeting of the Diamond Bar City Council. A. Disorderly behavior toward the Council or any member of the thereof, tending to interrupt the due and orderly course of said meeting. B. A breach of the peace, boisterous conduct or violent disturbance, tending to interrupt the due and orderly course of said meeting. C. Disobedience of any lawful order ofthe Chair, which shall include an order to be seated or to refrain from addressing the Board; and D. Any other unlawful interference with the due and orderly conduct of said meeting. INFORMATION RELATING TO AGENDAS AND ACTIONS OF THE COUNCIL Agendas for the regular Diamond Bar City Council meetings are prepared by the City Clerk and are available 72 hours prior to the meeting. Agendas are available electronically and may be accessed by a personal computer through a phone modem. Every meeting of the City Council is recorded on cassette tapes and duplicate tapes are available for a nominal charge. ADA REQUIREMENTS A cordless microphone is available for those persons with mobility impairments who cannot access the public speaking area. Sign language interpreter services are also available by giving notice at least three business days in advance of the meeting. Please telephone (909) 860-2489 between 8 a.m. and 5 p.m. Monday through Friday. HELPFUL PRONE NUMBERS Copies of Agenda, Rules of the Council, Cassette Tapes of Meetings (909) 860-2489 Computer Access to Agendas (909) 860 -LINE General Information (909) 860-2489 NOTE: ACTION MAY BE TAKEN ON ANY ITEM IDENTIFIED ON THE AGENDA. —� VOLUNTARY REQUEST TO ADDRESS THE CITY COUNCIL TO: FROM: ADDRESS: ORGANIZATION: AGENDA #/SUBJECI : CITY CLERK DATE: �l PHONE.(q) I expect to address the Council on the subject agenda item. Please have the Council Minutes reflect my name and address as written above. Signature L VOLUNTARY REQUEST TO ADDRESS THE CITY COUNCIL TO: CITY CLERK p� FROM: c__ f/�C� ,��ZS6-r,DATE: y— 4/ /S ADDRESS: J 0`�-n-1 PHONE:C� /` Z 3 ORGANIZATION: ( hoz AGENDA #/SUBJ ECT: I expect to address the Council on the subject agenda item. Please have the Council Minutes reflect my name and address as written above. Signature FA TO: FROM: ADDRESS: ORGANIZATION: VOLUNTARY REQUEST TO ADDRESS THE CITY COUNCIL AGENDA #/SUBJECT. CITY CLERK/ V rT A4 Y 7 !>sSd DATE: 9 4( ` Si / PHONE: g 4'J, 6 7 f Z. expect to address the Council on the subject agenda item. Please have the Council Minutes reflect my name and address as written above. Signature CITY OF DIAMOND BAR AGENDA REruxx TO: Mayor and City Council MEETING DATE: April 6, 1995 FROM: Terrence L. Belanger, City Manager AGRNDA NO. REPORT DATE: March 29, 1995 TITLE: Certification of Master Environmental Impact Report No. 91-2 and approval of Vesting Tentative Tract Map No. 47850, located easterly of Steeplechase Lane and south of Windmill Dr. adjacent to the private gated community known as "The Country". SUMMARY: The vesting tentative map proposes the subdivision of 73 acres into 57 single family residential lots and one common lot with a private looped street system accentuated with four cul-de-sacs. Proposed lots range in size from .43 acres to 5.65 acres in size. The map has been recommended for approval by the Planning Commission with conditions. RECOMMENDATION: It is recommended that the City Council open the public hearing, open the Joint Session with the Planning Commission, receive a presentation on the proposed development from the staff and applicant, receive public testimony, close the public hearing, and receive Planning Commission comments. Thereafter it is recommended that the City Council continue deliberation and direct staff appropriately. LIST OF ATTACHMENTS: X Staff Report _ Public Hearing Notification X Resolution(s) _ Bid Specification (on file in City Clerks Office) X Other MEIR and V'TM 47850 transmitted under separate cover. EXTERNAL DISTRIBUTION: The project applicant, Diamond Bar Associates. SUBMITTAL CHECKLIST: Has the resolution, ordinance or agreement been reviewed by the City Attorney? Does the report require a majority or 4/5 vote? Has environmental impact been assessed? Has the report been reviewed by a Commission? Which Commission? Are other departments affected by the report? Report discussed with the following affected departments: Engineering, LACFD, LACSD REVIEWED BY: / Terrence L. Belanger Frank M.slier City ~ City Manager Assistant City Manager X Yes _ No Majority X Yes _ No X Yes _ No X Yes _ No keseStefano ity Development Director CITY COUNCIL REPORT AGENDA NO. MEETING DATE: April 6, 1995 TO: Honorable Mayor and Members of the City Council FROM: Terrence L. Belanger, City Manager SUBJECT: Vesting Tentative Tract Map No. 47850 ISSUE STATEMENT: This matter requests approval of the Vesting Tentative Tract Map No. 47850, the subdivision of a 73 acre site located adjacent to "The Country" in upper Tonner Canyon and within Significant Ecological Area No. 15. and certification of the draft Environmental Impact Report to prepared to address the project impacts. Purpose of the Joint Public Hearing: VTM 47850 was component of a Draft Master Environmental Impact Report prepared in 1991 to address three proposed Vesting Tentative Tract Maps No. 47850, 47851 and 48487. In May 1992 the City approved VTM 47851 and 48487. In November 1992 the City Council denied VTM 47850. A lawsuit filed by the applicant in 1993 and a Settlement Agreement was entered into in April 1994. In accordance with the Agreement the purpose of the Joint Session is to consider VTM 47850, the applicant's compliance with geotechnical concerns raised in October 1992 and any other matters deemed appropriate. The Planning Commission recommended City Council approval of VTM 47850 in November 1991. BACKGROUND: Vesting Tentative Tract Map 47850 was initiated in 1989 by the applicant, Diamond Bar Associates, 3480 Torrance Blvd. Ste. 300, Torrance, CA. as a subdivision request with related applications for 57 lots proposed for custom home development. The subject map was one of three maps (Vesting Tentative Tract Map No. 47851 and No. 48487) submitted encompassing 160 acres and proposing 120 units. Initial processing and review was completed by Regional Planning and the project was then transferred to the City of Diamond Bar. The project is located in northern Tonner Canyon and within Significant Ecological Area (SEA) No. 15. The application necessitated that a Conditional Use Permit be acquired in order to develop in the SEA and hillside areas and an oak tree permit to remove 16 oak trees. The proposed project was required to prepare a Master Environmental Impact Report (MEIR) as a result of the evaluation initial study. The MEIR addressed the impacts related to development of the three tract subdivision as one project with different components. The MEIR addressed the proposed project and the Preferred Alternative which became the project of record. The preferred design alternative featured the incorporation of contour and landform grading whereas the initial project exhibited conventional grading techniques. Additionally, the project reflected measures identified by the Significant Ecological Area Technical Advisory Committee (SEATAC) to reduce the impacts germane to residential development in an SEA and in response to the City adopting a Hillside Management Ordinance (Ord. No. 14, 1990) which mandated grading techniques more aesthetically pleasing and favorable to hillside development. The project was reviewed by the Planning Commission in a series of public hearings beginning in September of 1991. At the October 28, 1991 Planning Commission hearing, testimony was taken from the public, staff and the applicant, At the conclusion of the hearing, the Commission directed staff to prepare Resolutions of Approval and to amend the draft conditions of approval to most notably preserve an additional 7 oak trees in the western most canyon. The project was returned to the Commission on the November 25, 1991. The Commission took action to certify the Master Environmental Impact Report for the purpose of approving the hillside development/SEA CUP's and oak tree permits and to recommend approval of the VTM 47850, 47851, and 48487 in addition to Certification of the MEIR. C. EErMRSIREP0R7sIVTM47850.00V 1 t iiv c..J �.�.___-�l l,eg�w Aelihorlrinn un the muicct in Janwary Qt too, �nnoludinv atter a saim yr vutall� several months. In June of 1992 the Council certified the MEIR anct approved VTM 47851 and VTM 48487 as recommended by the Planning Commission. Several issues arose out of the public hearing that focused on the geotechnical information on VTM 47850. The Council required the applicant to provide extensive information in order to respond to the questions. In November of 1992, the Council set a public hearing to deliberate on the project. The applicant had not provided the required information to respond to the plan check review questions in time for the public hearing and requested an extension of time to respond to the issues. The Council took action to deny the requested extension of time and additionally took action to deny the application without prejudice. In doing so, the Council found that they could not approve the project without definitive information on the geotechnical issues but allowed the applicant to submit a new application for the project once the information had been gathered. Subsequently, the applicant filed a lawsuit to appeal the decision. The lawsuit was resolved when the City and the developer entered into an out of court settlement agreement. The settlement agreement required the City to re-initiate processing of the project commencing with a Joint Session to be conducted with the Planning Commission. In anticipation of the renewed processing a revised environmental document was prepared. The revised document updated information related to air quality and biological resources as regulations and standards have changed and to the geotechnical information related to the 24 outstanding issues that served as the foundation for denial of the project. The revised draft MEIR was then circulated to responding agencies and for public review in compliance with the California Environmental Quality Act (CEQA). Project Description Vesting Tentative Tract Map No. 47850 is a 73 acre site located in northern Tonner Canyon. The 57 lot subdivision is proposed for a site which currently developed with extensive oak and walnut woodland. This project contains the most valuable biota of the three tracts proposed for development. VTM 47850 contains significant walnut woodlands that cover approximately 34 acres contain almost 700 trees. Approximately 110 oak trees are primarily found within two stands comprising 2.5 acres. The trees located in the southwest portion of the tract have been identified to be protected and contain some of the oldest and healthiest trees on-site. Sixteen oak trees have been marked for removal as a part of this project. These oak trees will be replaced at a 4:1 ratio as will all walnut trees removed as part of the project. The replacement trees have been grown from seeds collected on-site in order to ensure the continuation of the genetics of native plant community. The landscape plan for the project has been crafted to reproduce an environment that is compatible with remaining vegetation and natural habitat to be complementary with residential development and the mitigation measures recommended by the SEATAC. Geology The critical information that comprised the basis for the City Council's denial of the project is 1992 has been gathered and analyzed by the City's geotechnical consultant and City Engineer. There were 24 outstanding issues that focused on subsurface issues related to following areas: 1) identification soil materials thought to be bentonite clay; 2) the location and extent of shear keys to stabilize the development; 3) the provision of a map identifying the location of subsurface geologic features and surficial slump and earth units; and 4) supplemental information on the stability of proposed cut and fill areas. In the intervening period the applicant has provided the required information to the City and has satisfactorily resolved the outstanding issues. In order for the information to be gathered and analyzed, the applicant conducted additional physical explorations by deep boring and trenching of the site and concluded with numerous laboratory tests and analyses. As a result of the information generated by the additional testing the applicant was able to refine the information and to provide a more definitive understanding of the geology. Most notably, the earth material that had previously been thought to be bentonite clay was found to be smectitic silt. Analysis of the material found the strength parameters of the material C: ILEMRSMEPORMI V7M47&W.COV Lu d-.--- _P I- L-JAMOLI 919V The anAlYsiS d55UMC4 the most conservative parameters ana conuuat:A tow ii, u manner that assumed the material to have the weaker bentonite characteristics. Grading The grading required to implement this project is substantial and requires approximately 783,000 cubic yards of earthwork. Total grading for the revised project will entail approximately 45 acres with about 2.5 acres of off-site grading. The canyon to the west of VTM 47850 will be graded and reconfigured to a state closely resembling the existing topography with slopes approximating a range from 4:1 to a 2:1 maximum vertical incline. The grading will be balanced on-site and with the incorporation of landform grading techniques, the project site will reflect many of the same physical characteristics that are visible today. The grading plan has been revised from the 1992 plan to reflect adjustments to the design parameters. The majority of the grading previously proposed has not been affected and overall there will be additional grading on approximately two acres. The additional grading will be conducted on the east and west facing slopes of the project. The east facing slope has grading redesigned to not encroach as far west off-site and to become more focussed along the upper portion of the canyon and upper areas around the building pads. On the east facing slope additional grading is proposed to extend north and south and to primarily add additional buttressing and support to the pads. The adjustments to the grading plan are not significant and do not dramatically change the previously identified impacts of the project. All grading activities are required to take place outside the nesting season and all of the heavy equipment will be staged on-site. No access to the adjacent public residential streets will be afforded to the construction equipment and will only access the site via "The Country". Biota The project is located in SEA No. 15 in northern Tonner Canyon. All development projects within an SEA are required to obtain a conditional use permit. Review by the SEATAC is required prior to issuance of the CUP and that review was conducted in concert with the MEIR preparation. SEATAC reviewed the project from the perspective of actual and potential impacts to the ecosystem of the entire SEA. Although the project itself comprises less than 1.5 percent of the entire SEA, the potential impacts are not proportional and can impart adverse impacts on a geometric scale to the biology of the entire SEA. As a result of the issues identified by the SEATAC, the deficiencies in the design of the 1989 project became evident the applicant redesigned the project in its present form. Extensive information on the biological resources of the site and the site's relationship to the Tonner Canyon ecosystem have been collected and evaluated for this project. At the impetus of the SEATAC a Tonner Canyon Study was initiated and completed in 1991. The information brought together in that report in addition to the information collected within the MEIR for this project serve to provide a very clear understanding for staff of the value of this site. Additional information related to flora and fauna has been collected from the proposed project area. In 1994 three extensive surveys of the site were conducted by the City's environmental consultant to document the biological resources on-site. Extensive walnut and oak woodlands were found to be present on-site and were surrounded by coastal sage and chaparral scrub as well as non-native grasses. The surveys also identified an expected variety of wildlife species that primarily use the site for breeding, cover and food. Based on the size, location and other constraints to the site, the site is not considered a primary wildlife corridor. That is not to say that the site is not use for animals to traverse to other locations but that there is no significant resource other than Tonner Canyon and the SEA for the site to provide a connection to. The disruption to the site will displace wildlife during the grading and construction phases. With the recreation of habitat areas with native plants species and maintenance of the habitat areas until they are reestablished, most of the displaced wildlife will again utilize vast portions of the project site in the future. The removal of the oak and walnut trees will be mitigated by imposing a 4:1 replacement ratio. The remainder of the biota to be replanted in the restricted use areas will be reflective of the plant species which are native to the site. c:v. nTJtsixMroxTsrvrms7aso.cov 3 me JL-AlrAc rc..,mmbflded that the applicant C0110Gi br=b"Pleultz on-site prior iu grmunr uvtiYisivU L. J_.- ll,nl fltx replacement plants could be grown in nurseries. The result of this action is a perpetuation of the same genetics within the species of plants. The emphasis of this replacement procedure is reduce the impacts to the environment and to assist in transition of the plants back into the ecosystem. Vesting Tentative Map Staff has reviewed the tentative map for conformance with the City Council's approval of the VTM 47851 and VTM 48487. There are some issues that have been identified that require the Council's attention. The City Engineer finds that there are numerous easements referenced on the tentative map. These easements are both public and private in nature. The City has the ability to vacate the easements which have been offered to the County of Los Angeles. This is accomplished via the public hearing process, approval of the tentative map as proposed and recording of the final map The private easements however may not be vacated in this manner. To relinquish the private easements the applicant will be required to relocate those easements which may have an adverse impact on the net useable pad area. Staff has drafted a condition for consideration of this action. The intent is to guarantee that the lots within the subdivision can be developed to the greatest extent possible. Lot "A" is the common lot identified on the tentative as the location of the lift station. Staff recommends that the lift station be conveyed to the Homeowners Association for the purpose of ownership and maintenance of the site in the prescribed manner. An easement for sewer purposes will be dedicated over the necessary portion of the lot. Additionally, this lot should have a restriction to preclude residential building. Lots within the gated community approved by the City Council have been required to provide minimum lot frontages of 125 feet on all lots with the exception of cul-de-sac lots. These lots have been approved with 60 feet minimum lot frontages. This tract has been designed with four cul-de-sac streets. These streets have been designed with lots that primarily conform to the minimum standard. However, there are two lots which require an increase in the lot frontage. Staff finds that there are two alternatives that can be investigated to achieve compliance. The applicant can adjust the adjacent lot lines to substantially conform to the requirement or the applicant can join two lots to form one and reduce the overall number lots by one. Additionally, staff finds that the Remainder Parcel located in the southeastern portion of the tract should be joined with and adjacent lot (Lot No. 13, 15 or 26). This action would be consistent with the Remainder Parcel on VTM 47851 and will guarantee suitable access to the parcel. The site is currently the location of a Los Angeles County Fire Department (LACFD) helipad for emergency fire fighting especially for wildland fires. The Planning' Commission had recommended that the Council consider requiring the applicant to either provide an alternative location on-site or require the applicant to work with the LACFD in funding the development of an alternative site. The proposed map does not indicate that an alternative was identified on-site but staff recommends that the option remain. Alternative Projects The draft MEIR is required to analyze alternative projects to evaluate a comparison of potential impacts. For this project there were a total of seven alternatives generated for review and analysis. The "no project" alternative assumes the project site will remain in the current state with no change in any identified impact. Two somewhat less benign alternatives were put forth that essentially look at development of the site in two commercial agricultural uses. The "commercial agriculture -vineyard" use is a project scenario that requires some minimal grading although minimal slope stabilization would be required. The impact of this type of development would create no more significant impacts than the project of record. The "commercial agriculture -grazing livestock" alternative requires little grading. Grading would primarily be required to stabilize slopes in the areas with access roads and structural facilities. The major detrimental impact associated with this type of land use is the degradation of the plant habitat from overgrazing of the cattle. The mitigation measures necessary for this scenario would reduce these impacts to a level less than the proposed project. c:MrMRsiMroxrsivrMrrsso.COV 4 MUMMA I various dCgIOM Of density and design criteria. The 1989 project was prCx«4G1 as a realistic development alternative. Under this scenario, which proposea 57 single family units on the 73 acres, the project proposed conventional grading with linear grading techniques. Grading quantities for this concept would be less than the project of record but the visual and aesthetic impacts would be more apparent. The 50 percent reduction in density scenario would decrease the project to approximately 29 units. The design scheme would primarily reflect the same circulation system but would feature larger estate type lots. The overall impact of this alternative is consistent with the impacts associated with the current proposed development because the geotechnical corrections necessary for slope stabilization are the same. With the associated grading necessary for geotechnical stabilization, impacts to the biota would remain consistent as well. The "15 unit (74 percent reduction)" alternative would appear to reduce the project impacts in a manner corresponding to the density reduction. This is however not the case. Development of the 15 unit project requires that geotechnical stabilization be undertaken in the same manner similar to the grading plan proposed under the current project. As such, the grading required to stabilize the site would generate impacts that can be mitigated to a level of less than significant, as do the mitigation measures for the project of record. In summary, the alternatives identified vary in the extent of adverse impacts imparted on the site. The no development and agricultural uses generate less of an impact on the environment but are consistent with the land uses identified within the draft General Plan currently under consideration. These uses do not develop the site to its highest and best use and are not within the character of development within the area of the project. The reduced density projects do not yield projects with less cumulative impacts. The projects are still required to remediate the unstable soils conditions and in doing so impacting the biota of the site. The reduced density projects again deliver less development but do not reduce the environmental impacts and deliver projects that are less than the highest and best utilization of the project site. Conclusion: Staff has processed this application in conformance with the settlement agreement that mandated the City Council reconsider the project. In the intervening period the draft MEIR has been modified to address environmental standards that have changed since the project was initially reviewed. Additionally, the applicant and the staff have worked diligently to provide definitive information on the issues related to geology and geotechnical concerns. Staff has reviewed the voluminous information that the applicant has gathered by physical exploration and extensive analysis and has concluded review of the information as it relates to 24 unanswered questions that served as the foundation of the Council's denial of the project. The analysis has been deemed to fulfill the requirements set forth by the City. The applicant has developed a map which identifies the areas that contain surficial and subsurface landforms of note. The applicant has definitively resolved the issue surrounding bentonite on-site and has found the material to be a clay as smectitic silt. The strength of which exceeds that of bentonite and has revised the remedial work to correspond to these factors. The draft MEIR has been updated with current biota surveys. The surveys have identified no new issues and no new impacts have been identified. The mitigation measures identified for revegetation of disturbed areas are proposed to remain unchanged. The plants will be collected from the native plants and seeds on-site and will be planted and maintained until they are re-established (project maintenance for a maximum period of not less than five years). The draft MEIR also analyzed the alternative project designs. The projects with no development and commercial agriculture use do not have the same level of environmental impacts as the residential development projects. The land uses are not consistent with the land uses proposed within the draft General Plan and do no seem to be compatible with adjacent residential development. The reduced density projects yield less development but do not reduce commensurate environmental impacts proportionately. The required remedial grading is the same for the reduced density projects as C: tteMRSIasroxrsivnM47M. cov 5 is required for the project of record. PREPARED BY: Robert Searcy Associate Planner Attachments: Wilbur Smith Letters Dated March 30 and March 31, 1995 Response To Comments Mitigation Monitoring Program Vesting Tentative Tract Map No. 47850 C:IL 7nKSVneroxrsWM47&W.cov m Wilbur G. Smith 21630 Fairwind Lane Diamond Bar Calif. 91765 �� G 909-861-0742 a =i C z San Gabriel Valley Editor of Los Angeles Times Dear Ms. Klein Inclosed is communication between me and the Diamond Bar City Council on information I plan to present at the April 6, 1995 Public Hearing on VTTM No. 47850. I hope hope you will consider these points of view in your reporting on the hearing. In summary,I oppose approval of VTTM 47850 for the following reasons. 1) The developers technical documentation identifies the cause of past and potential future landslides due to a combination of smectite soil layers and groundwater/pore water pressure. 2) These documents confirm the presence of both these items within the tract boundaries. 3) The documents do not include groundwater or pore pressure in the Factor of Safety calculations which indicate the stabilit; of the slopes. 4) The County Code requires Factors of Safety of 1.5 or greater. These documents report Factors Of Safety of 1.5051,1.5093, 1.5011,1.5133 based on normal conditions. These values should exceed the County requirement by a greater amount to allow fo _Lrrors in the computational process.Also ,calculations should be mad based upon abnormal conditions such as adverse weather V (50-100 year rain seasons),uncertainties in geologic parameters,human deficiences in workmanship,etc,etc. 5) The report contains conflicting statements. The text states " groundwater was not incountered in any exploratary borings drilled on the site...' whereas the figures and tables show the presence of ground water. Because of these contradictions the truthfullness of these reports is questionable. Thanks � Q cj:j Wilbur G. Smith Wilbur G. Smith 21630 Fairwind Lane Diamond Bar Ca. 91765 909-861-0742 March 14,1995 To: City of Diamond Bar 21660 East Copley Drive Diamond Bar Ca. 91765 P,ECEIvEO CGS",,,!UNITY 46 d -Y c% Attn: Mayor P.Papen,City Council Members,J.DeStefano Subject: Vesting Tentative Track Map 47850 - Revision No.l (Five new references,three additions to ATTACHMENT B, identification of additional conflicting statements) Ladies and Gentlemen: Information (Attachment A) suppilied by the Cities Community Development and Engineering Departments has been reviewed for the purposes of providing citizen comment at Public Hearings to be held on the Crystal Ridge Development (VTTM 47850) and its Draft Environmental Inpact Report (Ref.5). Attachment B presents my citizen comments on the subject that I will present at these hearings and requests for actions to be taken by the City Council before voting on approval of the VTTM 47850. Please include this letter with attachments A and B in the final documentation of the Public Hearings. Thank You W ,t,U.� h , 4-24 Wilbur G. Smith ATTACHMENT A REFERENCES 1) Supplemental Geotechnical Investigation and Geotechnical Report Review Response for Subject Project, Dated April 28, 1994 by Harrington Geotechnical Engineering,Inc. 2) Supplemental Geotechnical Investigation and Grading Plan Review, Dated October 16,1992 by Harrington Engineering Inc. 3) Geotechnical Review Sheet for VTTM 47850, Dated October 29, 1992 by Leighton & Associates Inc. 4) Compilation of Geotechnical Report Review Sheets and Responses for Vesting Tentative Track 47850 dated August 29,1994 by Harrington Geotechnical Engineering Inc. 5) Revised Draft Environmental Impact Report for Vesting Tentative Map 47850 Vol 1 and 2 dated January 1995 by Michael Brandman Associates. 6) Case No. 71 16 84 filed in SUPERIOR COURT OF THE STATE of CALIFORNIA FOR THE COUNTY OF ORANGE; DATE 21 JUNE 1993. 7) Letter from DOUGLAS E.MORAN,INC to Harrington Geotechnical Engineering: Subject :Results of Shear Tests Performed Tentative Tract No.47850 ,dated April 14,1993. 8) Leighton and Associates letter to City of Diamond Bar: Subject: Tract Map No. 47851 dated August 2,1994. 9) Harrington Geotechnical Engineering,Inc Report NO.91-01-0109A (Tract 47851) 10) Harrington Geotechnical Engineering,Inc. letter to B.Mazur of D.B.A. dated July 6,1994. ATTACHMENT B COMMENTS and ACTIONS REQUESTED OF THE CITY COUNCIL BEFORE APPROVAL OF TRACK 47850 A) Direct the city attorney to give a legal opinion on the liability (degree and time periods) of D.B.A., City of Diamond Bar, J.C.C, and Leighton Associates for losses incurred by homeowners due to geologic hazards or errors in geotechnical calculations or assumptions. B) Reference 3 contains 24 specific questions that Leighton and Associates asked regarding Track 47850. These questions were elements in the law suite(Ref 6) filled by D.B.A against the city. D.B.A. responded to these questions in Reference 1. The city should now direct Leighton to make a definitive statement on each of the responses as to its adequacy and Leightons acceptance of the response. C) Stability analysis calculations are not adequate because they assume no groundwater and/or pore water pressure (Ref. 1 page 11). This assumption is not valid because it is physically possible for water to reach the smectite layer. To support this,Section 4.4 (Analysis of the Smectite Layer),page 10 states "other factors such as different topography and/or ground water buildup must also have existed at the time of failure and contributed to the slides". A clear contradiction exists here. Page 11 states no water, whereas page 10 indicates the existence of ground water buildup in the past. Therefore the Council should require that all stability analysis and Factor of Safety calculations are made with assumptions of finite amounts of groundwater and/or pore water pressure.Supporting this opinion is a statement in Ref.7) (page 3)"In using such parameters (cohesion and angle) to represent the strength of the material tested it is appropriate to recognize that shear strength is effectively reduced by pore water pressure which tends to neutralize confining pressure on which a significant portion of shear strength depends.This effect needs to be considered in an analysis of stability in which such parameters are used to represent material strength." D) Another deficiency in the reports is that Reference 2 (page 10) identifies a condition of bedrock creep (to depth of 100 ft.) caused by 1) cyclic changes in moisture content and density due to seasonal wetting and drying, 2) water in tension/shrinkage cracks, ...., 4) deep-seated,very thin bentonite (smectite) bed. However,Ref.2 page 11 states " ground water was not encountered in any of the excavations made at the site and is not expected to be a matter of future concern to the project under normal conditions .It is not reasonable to assume that because water was not encountered in these excavations that in will not occur at some future time, especially since there is evidence (land slides) that water was there in the past. Also the NO GROUNDWATER statement is qualified by NORMAL CONDITIONS. Analysis presented in these documents which vitally effects the fortunes and lives of so many people certainly should consider abnormal conditions such as adverse weather (50-100 year rainy seasons),uncertainties in geologic parameters, human deficiences in workmanship etc.,etc. The city council should require D.B.A. to conduct an error analysis of the Factor of Safety and other stability analysis computations using reasonable uncertainties in all system parameters (presence/amount of water,efficiency of blacket fills, geologic parameters. etc.,etc.) E) The COUNTY BUILDING CODE requires slope Factors of Safety greater than 1.5. The references presented Factors of Safety values of 1.5051, 1.5039, 1.5011, 1.5133, 1.5218,1.5602 ,1.6092. These values indicate that the tract design is very marginal from the COUNTY Factor of Safety prespective. Small errors in the computational process,the data used or assumptions made could cause many of these values to be less than the requirement which means the project would not be safe by County standards. The City Council should require D.B.A. to conduct an error analysis of the Factor of Safety computational process . Also the Council should require D.B.A to publish the Factor of Safety for each lot. F) The most significant aspect of Track 47850 is the presence of a smectite layer which lies from 30 to 100 ft. below the surface.If water reaches this layer earth movement(landslides) could occur. Existing landslides are evidence of this . The developers approach to preventing this is to place 10 or 3 ft. earth blankets on each lot to prevent the infiltration of surface water down to the smectite layer. Ref.9(page 26) states "Most of the instability of existing slopes (landslides and downslope creep) are believed to be attributed,at least in part,to the infltration of surface water into the underlying bedrock. In order to minimize water infiltration we have recommended that all lots,pads and graded slopes be covered with at least ten feet of compacted fill. Unforunately the developer presents no analysis of the effectiveness of this measure. He strongly recommends that the homeowner eradicate burrowing animals from blanket fills because their tunnels in conjunction with the many faults,cracks,fractures and joints identified in Ref.5 (VOL II, plates C-1 thru C-58) provide easy passage for water to the smectite layer. The City Council should require D.B.A. to find pest control professionals who will state the degree to which borrowing animals can be controlled in areas that are adjecent to much larger wilderness areas (such as Tonner Canyon) where no attempt is made to control them. Also D.B.A. should be required to access the effectiveness of the blanket fills in conjunction with the many open cracks,fractures,joints and faults below the fills as a means of preventing water reaching the smectite layer. G) Before approval of VTTM 47850 require Leighton and Associates to write a letter stating approval of the geotechnical conditions as was done for VTTM 47851 (Ref.8). H) Ask Leighton to comment on the low factor of safety values (1.5051,1.5039,1.5011,1.5133) relative to the County requirement of 1.5 presented in Ref./. /U , I) Ref.l page 11 states "...the potential for groundwater buildup and/or pore water pressure buildup within confined smectite silt strata that could affect the stability of the site is extremely remote. As a result, the inclusion of groundwater and/or pore water buildup was not considered appropriate for inclusion in the stabilit 'l analysis performed as part of this investigation.This conclusion is based in part on the following: * Groundwater was not incountered in any of the exploratory borings drilled on the site ..." These statements are contradicted by plates C -11,C -45,C-47 and C-48 in Ref.5 VOL II which shows water and/or seepage.Also Ref.7(page 3) clearly states that pore water pressure should be considered (see statement C in this Attachment). Consideration of VTTM 47850 should not be continued until these contradictions are resolved. J) A heavy burden is placed upon the homeowner to prevent potential geotechnical/earth movement problems by the need to ; 1) eradicate burrowing animals 2) have proper drainage of water from the lot 3) having and maintaining landscapeing 4) prevent excessive watering 5) proper design and maintainence (no leaks or cracks) of pools or spas. The potential homeowner should be advized that failures in the above areas could cause serious earth movement problems. Home Buyer's Awareness Package The Estates at Crystal Ridge Tract 47851 IMPORTANT INFORMATION CONCERNING THE AREA IN WHICH YOU ARE MAKING YOUR HOME PURCHASE YOU SHOULD READ THIS INFORMATION PRIOR TO MAKING A DEPOSIT TO PURCHASE YOUR HOME IN TRACT 47851 THE STATE OF CALIFORNIA, DEPARTMENT OF REAL ESTATE, HAS ISSUED A FINAL PUBLIC REPORT FOR THIS RESIDENTIAL DEVELOPMENT, A COPY OF WHICH MUST BE PROVIDED TO YOU BY THE SELLER. IN ADDITION, THE CITY OF DIAMOND BAR HAS REQUIRED THAT THE SELLER PROVIDE YOU WITH THIS BUYERS AWARENESS PACKAGE, WHICH PROVIDES SPECIFIC ADDITIONAL INFORMATION CONCERNING YOUR PURCHASE OF A HOME IN THIS DEVELOPMENT. GENERAL INFORMATION Whether you purchase your Crystal Ridge lot from Diamond Bar East Partners as part of a custom home package, or with the intent of building your own home in the future, there is important information concerning such real estate purchases in general and this development in particular of which you should be aware. The Property Owner/Developer - Diamond Bar East Partners, a California Limited Partnership 3480 Torrance Boulevard, Suite 300 Torrance, California 90503 Contact Kurt Nelson, (310) 540-3990 The Development Sales Office Location - 2810 Oak Knoll Drive, Diamond Bar, California Contact David Kaplan, (213) 849-2507 Title Statement - Fee title is currently vested in Diamond Bar East Partners, a California Limited Partnership. A policy of title insurance will be provided to you upon close of escrow, showing all liens and encumbrances of record. There are, in addition, certain utility easements and restrictions shown upon the final tract map as recorded, a copy of which may be reviewed upon request at either the City of Diamond Bar offices or those of Diamond Bar East Partners. 1 Covenants, Conditions and Restrictions Your lot is subject to a Declaration of Covenants, Conditions and Restrictions ("CC&Rs") which are intended to protect every owner's enjoyment of his or her home within tract 47851, as well as to fulfill certain conditions of land use imposed by the State of California and the City of Diamond Bar. The CC&Rs are recorded against every lot and bind every lot owner and his or her successors in interest. The CC&Rs govern or affect many important land use matters such as minimum residence size, architectural review, restrictions on use of the property, etc., and should be read and understood by all lot purchasers prior to close of escrow. If you have any questions concerning this document, contact Kurt Nelson of Diamond Bar East Partners, (310) 540-3990, or the City of Diamond Bar Community Development Department, (909) 396-5676. For convenience, some of the information from the CC&Rs has been condensed and outlined in this Buyer's Awareness Package. It is still important that you take the time to carefully read and understand the CC&Rs. Environmental Conditions Wildlife Habitat Natural wildlife habitat areas have been identified in the text and exhibits of your CC&Rs as "Natural Habitats" or "Open Space Habitats" (Article XV, Sec. 2). No owner may alter, modify or damage any of these areas without the consent of the City of Diamond Bar. Within these areas are "movement corridors" which are the pathways of travel utilized by the area's native wildlife. No fences or other barriers should be constructed within these areas except for fences approved by the City of Diamond Bar and the Crystal Ridge Estates Architectural Committee. Night lighting of the Natural and Open Space habitats is prohibited, and any lighting utilized on other portions of the lots should be directed away from these areas. It is also important to note that while animals commonly kept as household pets are permitted within Crystal Ridge Estates, they must not be allowed to roam outside the fenced boundaries of your home, except when being walked on a leash. Pet food can be an attraction to the local wildlife, and should be safely stored indoors within sealed containers, and immediately disposed of in closed trash receptacles after a feeding. Native Vegetation Preservation - Slope Maintenance Areas The Crystal Ridge Estates are located in a setting of natural canyons unique to Southern California. Many lots contain significant slope areas which have been carefully revegetated with native plants, including oak and walnut trees. Over these same slopes, established drainage patterns must be preserved. These areas have been delineated in the CC&Rs, and it is very important that every lot owner pay particular attention to the guidelines and restrictions contained in Article IV. No alterations in landscape, native vegetation or established drainage patterns may be made - within these areas without the written consent of the City of Diamond Bar and the Crystal Ridge Estates Board of Directors (or their Architectural _ Committee). No approvals shall be given in any event absent certification by a duly licensed civil engineer that the alterations are in keeping with City requirements, preserve proper drainage, and do not compromise the - geologic integrity of the slopes. Please note that certain potentially invasive plant species which might displace native vegetation may never be planted or allowed upon any lot within Crystal Ridge Estates, including: Blue Gum (Eucalyptus Globulus) Spotted Gum (Eucalyptus Maculata) Tree -of -heaven (Ailanthus Altissima) Brazilian Pepper Tree (Schinus Terebinthifolius) - Pampas Grass (Cortaderia Sellowianal) Fountain Grass (Pennisetum Setaceum) Spanish Broom (Spartium) Landscaping of Individual Residences Individual residences must be landscaped within ninety (90) days of issuance of certificate of occupancy by the City of Diamond Bar. Prior to issuance of a building permit, the contractor or owner/builder must �3 submit a landscape plan prepared by a landscape architect for approval by the City Department of Community Development. Prior to occupancy, if such approved landscaping is not completed, a bond or cash deposit must be posted with the City to assure completion within 90 days of occupancy. In the event that a home which begins construction unsold is purchased prior to its completion by a Buyer desiring a different landscape plan than that previously approved, a new landscape plan must be prepared and submitted to the City of Diamond Bar Community Development Department for approval. In preparing your lot's landscape plan special note should be taken of the restrictions on alteration of natural, re -vegetated slope areas, and of prohibited plant species as referenced elsewhere in this Buyers' Awareness Package. Consult with a landscape architect, arborist or botanist in preparing your landscape plan, and prior to introducing any non-native plant species. Restricted Use Areas, Geological Setbacks Portions of Lots 1 through 17, and all of lots 18 and 19 are shown on the final map of tract 47851 as "Restricted Use Areas" and are shown on Exhibit "A" to your CC&Rs as "Special Foundation Zone" areas. Due to their proximity to historic geological disturbance, these portions of the subdivision may not be built upon without the special consent of the City of Diamond Bar. This consent will not be given nor shall permits for any improvements upon these areas be issued unless submittals through a licensed engineer showing specially engineered foundations, footings or other underpinnings are approved by the City Engineer. Areas of these lots which are outside the delineated areas, and all of lots 20 through 48 of Tract 47851, are not subject to these restrictions. Urban Pollution Basins Urban Pollution Basins are drainage devices installed within the private streets of Crystal Ridge Estates in order to intercept potential pollutants such as motor oil or automotive coolant, which might otherwise flow into the surrounding canyons during the first rains following dry spells. While 4 these devices are helpful in controlling pollution, they are not a solution in themselves. No owner must ever knowingly cause such pollutants to be deposited onto the streets or into the drainage systems, and care should be taken to immediately repair any leaks of automotive fluids. Access Through Diamond Bar Country Estates Potential Annexation Access to the Crystal Ridge Estates lots is by easement through a guarded gate of "Diamond Bar Country Estates" Homeowners Association ("The Country"), thence over a portion of their private streets. These access rights are per a recorded legal settlement agreement which runs with the land, which is contingent upon a pro -rata cost contribution (as to security, street maintenance, insurance, etc.) from each lot owner within tract 47851 to Diamond Bar Country Estates. This pro -rata cost contribution as to access rights is covered through each lot purchaser's own Crystal Ridge Estates Homeowners Association dues as a component of the Dept. of Real Estate approved budget. However, in the event that any Crystal Ridge Estates lot owner wishes to make use of The Country's recreational common area facilities (swimming pool, tennis court and riding arena), an additional use fee of $4,500.00 plus additional monthly charges thereafter must be paid. As this Buyer's Awareness Package was being printed, negotiations were underway with The Country, whereby recreational facility use, access through the secondary Diamond Bar Country Estates Grand Avenue gate, and/or full annexation might be effected. Please take special note that by purchasing your lot in Crystal Ridge, you are giving your consent to vote for the annexation into Diamond Bar Country Estates if the two homeowners associations can come to terms. The Crystal Ridge Estates CC&Rs were written to be compatible with those of Diamond Bar Country Estates, but since annexation is a possibility, a copy of their CC&Rs is included with this Buyer's Awareness Package. Please contact Kurt Nelson at the Diamond Bar East Partners office (310) 540-3990 for further information or if you have any questions concerning these matters. 5 Educational Information This development lies within the Walnut Valley Unified School District. This District advises that the schools initially available are: Castle Rock Elementary School (1.5 miles from subdivision) 2975 Castle Road Diamond Bar, CA 91765 South Point Middle School (2.9 miles from subdivision) 26071 Larkstone Diamond Bar, CA 91789 Diamond Bar High School (.8 miles from subdivision) 21400 E. Pathfinder Diamond Bar, CA 91765 This school information was provided prior to the preparation of this Buyer's Awareness Package. For the most current information regarding school assignments, facilities and bus service, contact the Walnut Valley Unified School District, 880 So. Lemon Ave., Walnut, CA 91789 or by telephone at (909) 595- 1261. Utility Information Water - Walnut Valley Water District. District offices are located at 271 So. Brea Canyon Rd., Walnut, CA 91789-3002. Their telephone number is (909) 595-1268. Gas - Southern California Gas Company, (800) 427-2200 Electric - Southern California Edison Co. (818) 967-7411 Telephone - General Telephone Co. (800) 482-6711 0 Acknowledgment of Receipt The undersigned lot purchaser hereby acknowledges receipt of the following : 1) Buyer's Awareness Package; 2) Declaration of Covenants, Conditions and Restrictions for Tract 47851, By -Laws and Articles of Incorporation for the Crystal Ridge Estates Homeowners Association; - 3) Crystal Ridge Estates Homeowners Association Budget 4) California Dept. of Real Estate Public Report for Tract 47851; all of the above with respect to the purchase of lot No. of tract 47851. 7 mmGATION MONITORING PROGRAM VESTING TENTATIVE TRACT MAP 47350 CONDMONAL UW PERbffr NO. 89528 OAK TREE PSRMff NO. 89528 - EIR SCH NO. 90010506 Prepared for: City of Diamond Bar Community Development Department 21660 E. Copley Drive, Suite 1910 Diamond Bar, California 917,63-4177 Contact: James DeStefano, Planning Director Prepared by; Michael Brandman Associates 17319 Red Hill --Avenue; Suite 250 Irvine, California 92714 (714) 250-5555 Contact: Thomas E. Smith, Jr., AICD, Project Director' Michael E. Houlihan, Project Manager March 1995 MITIGATION MONITORING PROGRAM VESTING FOR TENTATIVE MAP 47850 Mitigation Measures Timing Responsible P Verification NATURAL LAND FORMS I . Major areas of fill shall not exceed a slope of two units horizontal to one unit vertical (2:1 slope maximum). 2. During and after construction, measures shall be taken to prevent erosion. These measures shall be listed and included within a developer -prepared erosion control plan which shall be approved by the City Engineer prior to commencing grading. 3. A security bond shall he posted with the City Engineer prior to commencement of grading. This bond shall be adequate to assure completion of grading per the approved plans for which a grading permit is issued. 4. An improvement bond shall be posted and a subdivision agreement shall be executed for the project development. 5. A qualified soils engineer shall confirm in writing that the proposed grading for Vesting Tentative Map 47850 will render the site safe from known geologic instabilities, to an acceptable margin of safety, based upon standard soils engineering practice. J a109030018.MMP During grading activities. Department of Public Works Prior to issuance of a grading Department of Public Works. permit. Field check. Review erosion control plan and field check. Prior to issuance of a grading Department of Public Works Receipt of bond. permit. Prior to issuance of a grading Department of Public Works Receipt of bond. permit. Prior to issuance of a grading Department of Public Works Review reports. permit. Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification 6. Grading and exterior construction activities shall begin no earlier than 7 a.m. and shall not continue past 5 p.m., Monday through Friday. Grading and exterior construction activities shall be restricted to 8 a.m. to I p.m. on Saturday. Transportation of equipment to and across the project site shall occur only within these hours. During grading and Department of Public Works Field check. construction activities. 7. The applicant shall establish a construction Prior to commencement of Department of Public Works Plan check and field review. staging area on the project site before grading activities. beginning preliminary grading. The construction staging area will provide for the storage of equipment, landscape materials, and building materials. 8. Onsite colluvium shall be removed during grading activities. In those cases where colluvium soils are used as fill, they shall be remolded and compacted to attain the required relative compaction of 95 percent for the proposed fill slopes and buttress. Representative testing of the compacted fill shall occur during grading in order to verify the design shear strength. 9. Gopher suppression measures shall be developed by the geotechnical consultant in order to control gopher tunneling and erosion of fill slopes. The gopher suppression measures shall be subject to review by the City's geotechnical consultant JB/09030018.MMP During grading activities Prior to issuance of a grading permit. Department of Public Works Department of Public Works Field check. Review reports and field check. Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification and to City Engineer approval prior to issuance of a grading permit. 10. All areas of unstable soils shall be modified During grading activities. Department of Public Works Field check. to correct the instability to a level of adequate safety based upon soils engineering criteria and standards. All areas of unstable soils shall be excavated and recompacted per the recommendations of the soil engineer. 11. As additional geotechnical studies are conducted, the project geotechnical engineer shall determine the number of additional borings/pits excavated onsite in order to further define geologic constraints and ensure safe and stable developments. These actions shall be subject to review by the City Engineer and the City's geotechnical consultant. HYDROLOGY and WATER QUALITY Prior to issuance of a grading Department of Public Works Plan check and review permit and during grading. reports. I . To aid in onsite water recharge and Prior to issuance of a grading Department of Public Works Plan check and review minimize undue channelization of drainage, permit and during grading. repo• minor tributaries shall be retained, reconstructed, or created to enhance percolation rather than run-off. 2. During grading and construction activities, During grading and Department of Public Works Plan check, review reports, the proposed reconstruction of disturbed construction activities. and field check. areas will be initiated as quickly as is feasible to prevent undue erosion and lessen J13109030019.ntMP 3 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification any non -point pollution impacts to surface run-off. Prior to issuance of a grading permit, an Prior to issuance of a grading urban runoff management plan shall be permit. prepared by a qualified hydrologist to control and reduce the amount of surface runoff generated by local precipitation events, including nuisance flows and the associated pollutants which may be transported along with storm waters into natural drainages. The plan shall be reviewed by a qualified biologist to ensure compatibility with biological resources. The conditions of the plan will be subject to approval by the City Engineer prior to issuance of a grading permit. The applicant shall ensure that a Seven days after completion of landscaping installation crew shall begin final grading and 60 days after work within 7 working days after completion of final grading. completion of final grading. The applicant shall ensure that all irrigation lines are properly installed and functional within 60 days after completion of final grading. This will occur following the final grading phase of each tract. Department of Public Works Applicant and Department of Public Works Plan check and review urban runoff management plan. Field check. 5. The applicant shall ensure that all erosion During grading and Applicant and Department of Field check. control devices and measures are properly construction activities. Public Works installed in a timely manner. This will occur before, during, and following all grading phases of each project. J9/09030016.MIIIP 4 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification NOISE l . All construction equipment shall be During grading and Department of Public Works Field check. properly muffled to reduce noise levels. construction activities. 2. Transportation of equipment and materials During grading and Department of Public Works Field check. and operation of heavy equipment shall be construction activities. limited to the hours of 7 a.m. to 5 p.m. on weekdays and 8 a.m. to 1 p.m. on Saturdays. CLIMATE AND AIR QUALITY I . Prior to the issuance of a grading permit, Prior to issuance of a grading Department of Community Plan check. the project applicant shall demonstrate to permit. Development the satisfaction of the City Engineer how the following measures recommended by the City or the South Coast Air Quality Management District have either been incorporated into the project construction guidelines or provided sufficient evidence to the City that a particular measure is not feasible to implement. a. Apply approved chemical soil stabiliz- ers according to manufacturers' speci- fications to all inactive construction areas (previously graded areas inactive for 4 days or more). b. Replace ground cover in disturbed areas per City specifications. JB/09030018.MMP 5 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification c. Enclose, cover, water twice daily, or apply approved soil binders, according to manufacturers' specifications, to exposed stockpiles (i.e., gravel, sand, dirt). d. Water active sites at least twice daily. e. Suspend all excavating and grading operations when wind speeds (as instantaneous gusts) exceed 25 miles per hour (mph). f. Monitor for particulate emissions according to South Coast Air Quality Management District specified proce- dures: for information call (909) 396- 3147. g. in field trailers, use portable air conditioning units powered by nondiesel equipment. h. Sweep streets at the end of day if any visible soil material is carried over to adjacent thoroughfares (recommend water sweepers which use reclaimed water). i. The City may require that gravel be used in unpaved areas used as either construction roads or staging areas for construction equipment. JBl09030018.MMP 6 Mitigation mumming riupwll Vesting Tentative Map 47850 Mitigation Measures Timin Responsible Party Verification j. Apply water twice daily for chemical soil stabilizers according to manufacturers' specifications to all unpaved parking or staging areas and unpaved road surfaces, if required for dust control. k. Install wheel washers where vehicles exit unpaved roads onto paved roads, or wash off trucks and any equipment leaving the site every trip in designated areas on the site. I. Traffic speeds on all unpaved roads surfaces to be reduced to 15 mph or less. in. All trucks hauling dirt, sand, soil, or other loose materials are to be covered and should maintain at least 6 inches of freeboard (i.e., minimum required space between top of the load and top of the trailer, based upon a level load. n. Pave construction roads that have a traffic volume of more than 50 daily trips by construction equipment, 150 total daily trips for all vehicles, for 12 consecutive days. o. Pave all construction access roads at least 100 feet onto the site from the main road. 7 Mitigation Monitoring Program IB/09030018.MMP Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification p. Use methanol or low -sulfur pile drivers. q. Use low -sulfur fuel for stationary construction equipment pursuant to Rule 431.2 r. Suspend use of all construction equipment operations during second stage smog alerts. For daily forecast, call (800) 242-4022 (Los Angeles County). s. Use construction equipment that has catalytic converters (for gasoline powered equipment). t. Prevent trucks from idling longer than 2 minutes. u. Configure construction parking to minimize traffic interference. v. Provide temporary traffic control during all phases of construction activities to improve traffic flow such as providing a flag person to direct traffic and ensure safe movements off the site as directed by the City Engineer. w. Schedule construction activities that affect traffic flow to off-peak hours (i.e., between 10 a.m. and 3 p.m.) with approval from the City. JB/09030018.MMP 8 Mitigation Monitoring rrogratn Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification 2. Prior to the issuance of a building permit, Prior to issuance of a building Department of Community Plan check. the project applicant shall demonstrate to permit. Development the satisfaction of the City Engineer how the following measures recommended by the South Coast Air Quality Management District have been incorporated into the project. a. Use of solar or low -emission water heaters. b. Use of central water heating systems. c. Use of built-in energy-efficient appliances. d. Building and subdivision orientation should be to the north for natural cooling. e. Provide shade trees to reduce building heat. f. Use of energy-efficient and automated controls for air conditioners. g. Use of double -glass paned windows. TRAFFIC and CIRCULATION 1. To improve traffic operations at the Shadow Prior to issuance of a building Department of Public Works Receipt of impact fee. Canyon/ Diamond Bar Boulevard permit. intersection, the City as a part of its long J9/09030018.MMP 9 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification range planning process has installed a traffic signal at this location. Prior to the approval of a final map, the applicant shall submit a pro -rata share for this improvement to the City of Diamond Bar Public Works Department. 2. Due to forecasted traffic growth in the Prior to issuance of a building Department of Public Works Receipt of Impact fee. study area, a separate left -turn lane should permit. be installed in the southbound direction at the intersection of Diamond Bar Boulevard and Brea Canyon Road to increase the level of service from Level of Service "E" to an acceptable level. The need for this additional lane occurs under the traffic condition of existing plus future background plus Project traffic. This impact is not significant individually, but could be defined as significant cumulatively. Prior to the issuance of a building permit, the applicant shall submit its incremental (pro - rata) share to the City of Diamond Bar Public Works Department for a separate left -turn lane in the southbound direction at the intersection of Diamond Bar Boulevard and Brea Canyon Road. 3. In addition, a stop sign should also by Prior to issuance of a building Department of Public Works Receipt of impact fee. installed at the intersection of Wagon Train permit. Lane and Steeple Chase Lane in order to minimize any vehicular conflicts in the intersection. The stop sign should be installed on Wagon Train Lane (stem of the 10 Mitigation Monitoring Program J11109030018 MMP Vesting Tentative Map 47850 Mitigation Measures Timing Responsible P Verification tee intersection) along with fifty feet of double yellow striping and Type D raised pavement markers, stop legend and limit line. Prior to the issuance of a building permit, the applicant shall submit its incremental (pro -rata) share to the City of Diamond Bar Public Works Department for a stop sign at the intersection of Wagon Train Lane and Steeple Chase Lane. 4. The project applicant shall provide its fair Prior to issuance of a building Department of Public Works Receipt of impact fee. share contribution toward striping a permit. separate right -turn lane and installing appropriate signs in the southbound direction at the intersection of Diamond Bar Boulevard and Pathfinder Road. 5. The project applicant shall provide its fair Prior to issuance of a building Department of Public Works Receipt of impact fee. share contribution toward striping a permit. separate right -turn lane and installing appropriate signs in the northbound direction at the intersection of Diamond Bar and Shadow Canyon Drive. 6. Parking for construction employees and During grading and Department of Public Works Field check. equipment will be provided on the construction activities. construction site, and no parking will be permitted on existing streets. 7. No fencing, planting materials, or Prior to approval of street Department of Public Works Plan check and field check. obstruction of any kind (over 30 inches improvement plans. high, as measured from the top of the curb), shall be allowed in the clear sight JB109030018 NIMP 11 ivrniganon wrvnuunng rivg1wil Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification triangles (50'x50') at the intersections of the main access roads which serve the project site. 8. The project applicant shall provide its fair Prior to issuance of a building Department of Public Works Receipt of impact fees. share contribution toward the construction permit. of a sidewalk along the eastside of Diamond Bar Boulevard across from the Country Hill Shopping Center. BIOLOGICAL RESOURCES Walnut Woodland A walnut woodland revegetation program shall be approved by the City of Diamond Bar prior to the issuance of grading permits. The program shall include walnut woodland replacement guidelines that address mitigation site selection, site preparation, irrigation system design, planting (planting sizes and densities by species), and maintenance (weed control, irrigation requirements, and plant replacement). Monitoring guidelines shall be established that will include performance standards (percent survival and percent cover standards for planted species), monitoring methodology, and reporting requirements. To ensure the replacement of ecosystem values and not just of trees, native understory plant species shall be included in the walnut woodland Prior to issuance of a grading Department of Community Review revegetation program permit. Development and field check. JB/09030018.MMp 12 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification revegetation program. Understory plant species shall be grown and obtained from native plant suppliers. Walnuts planted in the fuel modification areas shall follow the guidelines. 2. Replacement walnuts shall be planted within protected open space areas onsite in need of habitat enhancement and where long-term wildlife values can be realized. If this criteria cannot be met onsite, replacement of walnuts removed by project implementa- tion shall be performed offsite at locations agreed upon by the CDFG and the City of Diamond Bar. An offsite location shall be designated prior to the issuance of a grading permit for VTM 47850. 3. All walnuts removed during project implementation shall be replaced at a ratio of 2:1, with a minimum container size of 5 gallons. Planting shall occur between November and April. Walnut replacement shall not exceed 45 replacement trees per acre (with understory) or 30 trees per acre (without understory). The project proponent shall avoid and preserve walnut trees to the maximum extent possible within the grading plan. Prior to issuance of a grading Department of Community permit. Development Prior to issuance of a building Department of Community permit. Development Plan check, field check, and evidence of fund contribu- tion. Field check. 4. Walnut woodland revegetation areas shall Annual reports over a period of Department of Community Field check and review be maintained (weed control and 3 years from completion of Development annual reports. supplemental irrigation) by the subdivider grading. JB109030018.MNIP 13 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification for a minimum of 3 years following planting to ensure the successful establishment and long-term survival of the habitat. Irrigation shall be gradually curtailed by the end of the third year to ensure that the woodland plantings can survive without long-term supplemental irrigation. All walnut woodland replacement efforts Annual report over a period of Department of Community shall be monitored by the subdivider for a five years from completion of Development period of 5 years. Yearly monitoring grading. reports shall be submitted to the City of Diamond Bar. These monitoring reports shall document the success of the replacement efforts (percent survival of replacement plantings, percent cover, and height data) and any required remedial actions. At the end of the 5 year monitoring period, the performance standard shall be two live replacement walnut trees for each walnut tree removed. Coast Live Oak Woodland 6. The feasibility of relocating small- to Prior to issuance of a grading Department of Community moderate-sized oaks, not currently proposed permit. Development for relocation, shall be analyzed for use in the oak replacement efforts. Consideration shall be given to collecting oak acorns onsite for germination and use in the oak woodland mitigation efforts. An oak woodland revegetation plan shall be Field check and review annual reports. Review revegetation plan and field check. 7B/09030018.MMP 14 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification approved by the City of Diamond Bar prior to the issuance of a grading permit. The plan shall include a program to reduce the amount of surface runoff reaching oak woodlands. Surface runoff from impermeable surfaces, irrigation systems, and construction areas shall be directed away from oak woodlands by means of a swale, French drain, or similar device. All oaks within the upland habitat removed as a result of project implementation shall be replaced at a ratio of 4:1. To ensure the replacement of ecosystem values and not just of trees, native understory plant species shall be included in the oak woodland replacement program. Oak replacement shall include 64 replacement oaks in upland habitat. Oak replacement shall not exceed 45 replacement trees per acre. All oak woodland replacement container stock shall be inoculated with mycorrhyzal fungi to enhance plant establishment. Replacement oak trees shall consist of the following mix of sizes: • 5 percent - 5 gallon • 25 percent - 15 gallon • 50 percent - 24 -inch box 0 20 percent - 36 -inch box 7. The replacement requirements for riparian- Prior to issuance of a building California Department of Fish Receipt of 1600 Agreement. associated oaks to be removed by project permit. and Game implementation shall be determined through JB/09030018.MMP 15 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification discussions with the California Department of Fish and Game as part of the Section 1600 process. The riparian -associated oaks removed as a result of project implementation shall be replaced at a ratio of a minimum of 3:1. Oak replacement shall include 21 replacement oaks in riparian habitat. 8. Replacement oaks shall be planted within protected open space areas in need of habitat enhancement and where long-term wildlife values can be realized. If this criterion cannot be met onsite, replacement of oaks removed as a result of project implementation shall be performed offsite. An offsite location shall be designated prior to the issuance of a grading permit for VTM 47850. 9. Oak woodland revegetation areas shall be maintained (weed control and supplemental irrigation) by the subdivider for a minimum of 3 years following planting to ensure the successful establishment and long-term survival of the habitat. Irrigation will be gradually curtailed by the end of the third year to ensure that the woodland plantings can survive without supplemental irrigation. Prior to issuance of a grading permit. Annual reports over a period of 3 years from completion of grading. Department of Community Plan check, field check, and Development evidence of fund contribution. Department of Community Field check and review of Development annual reports. 10. All oak woodland replacement efforts shall Annual reports over a period of Department of Community Field check and review of be monitored by the subdivider for a period 5 years from completion of Development annual reports. of 5 years. Yearly monitoring reports shall grading. JB/09030018.Mr1P 16 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible PartY Verification be submitted to the City of Diamond Bar. These monitoring reports shall document the success of the replacement efforts (percent survival of replacement plantings, percent cover, and height data) and any required remedial actions. At the end of the 5 -year monitoring period, the performance standard shall be two live replacement oak trees for each oak remediation. Riparian Habitats 11. Prior to the issuance of a grading permit, a Prior to issuance of a grading mitigation plan addressing potential impacts permit. on streambed, wetlands, or riparian habitats shall be prepared by the subdivider in conjunction with an application for a Section 404 permit from the U.S. Army Corps of Engineers (ACOE) and a Section 1603 Agreement with the California Department of Fish and Game. These agencies typically require the replacement of lost habitat values through the enhancement of remaining streambed, wetland, or riparian habitat, or through the creation of new areas of such habitat. The mitigation plan for riparian habitats shall outline procedures for mitigation site preparation (clearing, grading, topsoil storage), irrigation, planting (seeding, container plantings, transplantation), and maintenance (weed control, irrigation scheduling, replanting). Hydrological JBI09030018.MMP 17 U.S. Army Corps of Engineers and California Department of Fish and Game Receipt of. Section 404 permit. Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification studies shall be performed to determine if groundwater levels and surface water flows will be adequate to sustain the restored riparian habitat once established. Methodologies and requirements shall be specified in the mitigation plan for monitoring of the riparian habitat replacement efforts, including performance criteria and provisions for documenting the results of the replacement efforts through the end of the monitoring periods. Provisions to insure the long-term preservation of riparian mitigation areas shall be identified. Riparian habitat replacement programs shall be submitted to the U.S. Fish and Wildlife Service (as biological advisor to the ACOE) and the CDFG for review and approval. 12. Riparian mitigation implementation shall be Prior to issuance of a building Department of Community Field check. completed as soon as practicable following permit. Development completion of project grading. 13. Riparian mitigation shall be monitored by Annual reports over a period of Department of Community Field check and review of the subdivider for a 5 -year period following 5 years from completion of Development, U.S. Army annual reports. planting. The subdivider shall submit grading. Corps of Engineers, and annual reports discussing the survival rate California Department of Fish of the mitigation to the City of Diamond and Game Bar. IB/o9o3001 a. MMP I8 Mitigation Monitoring Program Vesting Tentative Map 47850 mitigation Measures Timing Responsible Party Verification Natural Habitats Impacted During Construction 14. Prior to the issuance of a grading permit, Prior to issuance of a grading Department of Public Works the limits of proposed grading and permit. construction activities shall be delineated with 8 -foot lengths of PVC pipe, mounted on a rigid steel base for support. The first 18 to 24 inches of topsoils should be scraped and stockpiled during grading. This will be used in the replanting of trees. 15. Prior to the initiation of vegetation clearing Prior to issuance of a grading Department of Community or grading, all oaks and walnuts within 200 permit. Development feet of construction activity shall be marked for either protection, relocation, or removal, both in the field and on construction site plans. Oaks and walnuts to be retained shall be protected from construction damage through the installation of temporary, rigid fencing. Fencing shall be a minimum of 4 feet high and located at least 15 feet outside the dripline of any oak or walnut or group of oaks/walnuts. No equipment storage or other activities shall be allowed within these fenced areas. Fencing shall remain in place for the duration of construction activities. 16. A biological resource monitor, approved by During construction activity. Department of Community the City of Diamond Bar, shall be onsite Development during construction to ensure adherence to all habitat protection measures. JB109030018.111MP 19 Plan check and field check. Plan check and field check. Field check. Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification 17. In compliance with Section 3503.5 of the California Fish and Game Code, a qualified biologist shall determine the presence of any raptor nests prior to or concurrent with grading activities, the project applicant shall contact CDFG, shall obtain and comply with all appropriate procedures relative to grading operations in proximity to those nests, and shall provide verification of same to the City. Resulting mitigation measures may include restricting construction activities near raptor nesting sites during and immediately following the breeding season. Prior to issuance of a grading Department of Community Review qualified biologist's permit and/or during grading. Development verification. 18. Pre -construction meetings shall be held Prior to commencement of Department of Community Field check. between the biological resource monitor and grading and construction Development construction supervisors and equipment activities. operators to review and ensure adherence to all habitat protection measures. 19. During construction, measures to prevent During construction activities. Department of Public Works Field check. erosion, such as use of silt fencing or hay bales, shall be installed at the limits of grading. 20. During construction, vehicle haul routes During construction activities. Department of Community Plan check and field check. between cut and fill locations shall be Development restricted to a minimum number. Earth- moving equipment shall be confined to the narrowest possible corridor during construction. Waste dirt or rubble shall not be deposited on adjacent native vegetation. JB109030018. MNIP 20 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timin Responsible Party Verification Vehicle haul routes shall be identified on construction plans and marked in the field, in consultation with a qualified biologist, to ensure minimization of impacts to biological resources. Trenching for utilities and irrigation lines shall be conducted outside the dripline of individual oaks or oak woodlands. Natural Habitat Impacts Associated With Fuel Modification 21. All fuel modification requirements, such as Upon completion of selective clearing, pruning, and wet zones, revegetation. shall be prohibited within 15 feet of the dripline of any individual oak tree or within 50 feet of the dripline of any oak woodland, except as otherwise required by the fire marshall. 22. All large native shrub specimens (5 -inch Upon completion of caliper or larger at base) within fuel revegetation. modification zones shall remain in place, except as otherwise directed by the fire marshall. Large native shrubs within the fuel modification zone may be thinned and pruned of all deadwood to reduce the fuel load. Only highly flammable vegetation, such as chamise, sages, and non-native grasses should be selectively removed, as required by the fire marshall. 23. All thinning or selective clearing of Upon completion o f vegetation within the fuel modification zone revegetation. Los Angeles County Fire Plan check and field check. Department Los Angeles County Fire Field check. Department Los Angeles County Fire Field check. Department 21 Mitigation Monitoring Program JB/o9030018.MMp Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification should be completed by hand to prevent the disturbance of the soil structure or vegetation to be preserved. No herbicides shall be used. Thinning should be done in a manner to maintain a natural appearance. 24. The irrigated wet zone should serve as both Upon completion o f a fuel modification zone and as a buffer revegetation. zone/transition area between the residences and the open space area, and should be designed to limit human intrusion. Post -Construction Impacts to Biological Resources 25. The following list of plant species shall not be permitted in the landscape plan in any development areas (i.e., common areas and private lots). These plants may potentially invade natural areas and displace native plant species. Such non-native species include ice plant (Delosperma spp.), blue gum (Eucalyptus globulus), spotted gum (Eucalyptus maculata), tree -of -heaven (Ailanthus altissima), Brazilian pepper tree (Schinus terebinthifolius), Peruvian pepper tree (S. molle), pampas grass (Cortaderia sellowiana), fountain grass (Pennisetum setaceum), Spanish broom (Spartium junceum), German ivy (Senecio mikaniodes), periwinkle (Vinca major), tamarisk (Tamarix sp.), hottentot fig (Carpobrotus edulis), Jupiter's beard (Centranthus tuber), Melia sp., cape Prior to issuance of a grading permit. Los Angeles County Fire Department Department of Community Development Plan check and field check. Review landscape plan and field check. ]B/o9030018.MMP 22 rvuugauvu JTi 111 111r� 11WJ5...... Vesting Tentative Map 47850 Mitigation Measures Timin Responsible Party Verification honeysuckle (Tecomaria capensis), and plumbago (Plumbago auricolata). 26. Landscaping within common areas and Prior to issuance of a grading buffer zones shall be restricted to the use of permit. native plants. These should include only those species that were found to occur on the site or in the immediate vicinity prior to grading. Such native species include laurel sumac (Malosma laurina),' lemonadeberry (Rhus integrifolia), California sagebrush (Artemisia californica), Mexican elderberry (Sambucus mexicana), coast live oak (Quercus agrifolia), scrub oak (Quercus dumosa), California black walnut (Juglans californica), white sage (Silva apiana), purple sage (Salvia leucophylla), black sage (Salvia mellifera), toyon (Heteromeles arbutifolia), fuschia-flowered gooseberry (Ribes speciosum), western poison oak (Toxicodendron diversilobum), coyote brush (Baccharis pilularis), mulefat (Baccharis salicifolia), thistle (Cirsium sp.), California everlasting (Gnaphalium californicum), saw-toothed goldenbush (Hazardia squarrosa), telegraph weed (Heterotheca grandiJlora), coastal goldenbush (Isocoma menziesii var. menziesii), California dodder Cuscuta califomica), rattlesnake weed (Chamaesyce albomarginata), Santa Barbara locoweed (Astragalus trichopodus), deerweed (Lotus scoparius), lupine (Lupinus sp.), purple sage -black sage Department of Community Review landscape plan and Development field check. 23 Mitigation Monitoring Program 7Bl09030018.MMP Vesting Tentative Map 47850 Mitigation Measures Timimz Responsible P Verification hybrid (Salvia leucophylla x Salvia mellifera), mesa bushmallow (Malacothamnus fasciculatus), holly -leaved redberry (Rhamnus ilicifolia), chamise (Adenostoma fasciculatum), narrow -leaved bedstraw (Galium angustifolium), arroyo willow (Salix lasiolepis), orange bush monkey -flower (Mimulus aurantiacus), chaparral nightshade (Solanum xanti), western verbena (Verbena lasiostachys), big leaf mistletoe (Phoradendron macrophyllum), giant wild rye (Leymus condensatus), and purple needlegrass (Nassella pulchra). Landscaping on private lots may use non-native plants. 27. Prior to the issuance of grading permits, an urban runoff management plan prepared by a qualified hydrologist shall be developed to control and reduce the amount of surface runoff generated by local precipitation events, as well as nuisance flows, and the associated pollutants that may be tran- sported along with stormwaters into natural drainages. The plan shall be reviewed by a qualified biologist to ensure compatibility with biological resources. The conditions of the plan will be subject to approval by the City Engineer prior to issuance of a grading permit. 28. Prior to the issuance of building permits, a Buyer Awareness brochure shall be Prior to issuance of a grading permit. Prior to issuance of a building permit. Department of Public Works Department of Community Development Review Urban Runoff Management Plan. Review Buyer's Awareness brochure. 24 Mitigation Monitoring Program JB/090300 MMMP Vesting Tentative Map 47850 Mitigation Measures Timin Responsible Party Verification developed to provide residents with information on surrounding natural habitats and resident wildlife, as well as guidelines to ensure the continuation of wildlife values of surrounding habitats. Guidelines to be incorporated into this brochure include domestic pet control, landscaping around mature oaks, native landscaping, and appropriate behavior in natural open space areas. 29. Successful integration of development into Prior to issuance of a building wildlife habitat depends on proper buffering permit. at the interface of these two areas. Development often results in an edge condition where residential lots are located adjacent to areas of natural open space. A conceptual buffer plan using native plant species has been developed for the management of this edge condition. This buffer will limit potential impacts to the natural areas by screening development from wildlife, capturing excess runoff from landscape irrigation that could potentially injure sensitive plants, and providing an edge along residential lots that is aesthetically pleasing while providing many plant species that are valuable to wildlife. This edge shall be designed so that it may be integrated into a fuel modification plan for the development that meets the requirements of the Los Angeles County Fire Department. Department of Community Review buffer plan. Development 25 Mitigation Monitoring Program JB/09030018.MNIP Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Pgq Verification Native plants recommended for this buffer include mesic species such as toyon, California black walnut, and Mexican elderberry. Additional native plant species that are low growing and of low fuel volume, and would not impede views into natural areas, could also be used. These include golden yarrow (Eriophyllum confertiflorum), California poppy (Eschscholzia californica), monkey flower (Diplacus SPP.), heart -leaved penstemon (Keckiella cordifolia), California fuchsia (Epilobium spp.), deerweed (Lotus scoparius), annual lupine (Lupinus spp.), Opuntia spp., and Baccharis 'Twin Peaks.' This zone shall be periodically thinned to maintain low fuel levels, and should be cleared of invasive grasses. To help all plants mature as quickly as possible and maintain all plant materials in optimum condition, irrigation facilities shall be installed as appropriate on slope areas and maintained by the applicant until sold. Maintenance shall then be the responsibility of the property owner. The use of fertilizers and pesticides within transition zones shall be minimized. Only nonresidual herbicides shall be used to control persistent invasive species within the landscape buffers. Mechanical clearing 26 Mitigation Monitoring Program JE/09030018.MMP Vesting Tentative Map 47850 Mitigation Measures Timin Responsible Party Verification techniques such as grubbing and mowing, and hand removal shall be used to eliminate less persistent invasive species. Subject to approval by the City of Diamond Bar, the applicant shall provide for the following: a. Physical specification on the type and degree of fencing allowed. b. Enforcement of a mandatory leash law. c. Guidelines for the maintenance of trash receptacles and uneaten pet food. d. Prohibition of the outside storage of pet food. e. The urban pollution basins shall be maintained by the subdivider. The City of Diamond Bar shall reserve the right to maintain the urban pollution basins and collect their costs should efforts by the subdivider not meet City standards. f. Existing dirt roads within the open space area shall be used as pedestrian/hiking/equestrian/biking trails as much as possible. Any additional trails shall be designed to avoid sensitive biological resources. Barbed wire or split rail fencing shall 27 Mitigation Monitoring Program J 109osoo18.MMP Vesting Tentative Map 47850 Mitigation Measures Timing Responsible P Verification be considered for highly sensitive areas subject to possible human intrusion. Hunting shall not be allowed within the open space areas. Unauthorized vehicular use shall be restricted within the open space areas. All trash (man-made materials) shall be removed from natural open space areas on a regular basis. Invasive weedy species such as giant reed, fennel, and artichoke thistle shall be monitored by the subdivider and, if necessary, these invasive plant species shall be removed. 30. Signs shall be located in appropriate areas Prior to issuance of a building Applicant, HOA, and Field check. to discourage human intrusion into natural permit. Department of Community open space and the Tonner Canyon SEA Development No. 15. 31. The effect of night lighting on wildlife shall be mitigated through the use of low - intensity street lamps at the edge of development, low -height lighting poles, and shielding by internal silvering of the globe or external opaque reflectors. Prior to issuance of a building permit. Applicant, HOA, and Field check. Department of Community Development 28 Mitigation Monitoring Program 7a109030018.MMP Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification AESTHETICS and VISUAL RESOURCES during grading, construction, or any I All residential units on the project site shall Prior to issuance of a building Department of Community Review setback information. . include setbacks from proposed property permit. Development lines. The applicant shall submit setback archaeologist can examine the find in place information to the City for approval. and determine its significance. If a find is ARCHAEOLOGICAL RESOURCES determine proper methods of handling the 1. The applicant shall have the name and Prior to issuance of a grading Department of Public Works Field check. telephone number of a City of Diamond permit. activity may resume, after the artifact is Bar -approved licensed archaeologist either retrieved or found to be not an available at the construction site. 3. Should a bonafide cultural, historical or 2. In the event a suspected cultural, historical During grading and construc- Department of Community Field check and review archaeologist's findings. or prehistorical resource is encountered tion activities. Development during grading, construction, or any activity associated with development of the site, the applicant shall insure that all activity will cease in the vicinity of that suspected resource until a qualified archaeologist can examine the find in place and determine its significance. If a find is authenticated, the archaeologist will determine proper methods of handling the artifacts for transport and placement in an appropriate repository. Construction activity may resume, after the artifact is either retrieved or found to be not an artifact of consequence. 3. Should a bonafide cultural, historical or During grading and Department _of Community Review monitoring report. prehistorical resource be encountered, the construction activities. Development JB109030018.MMP 29 Mitigation Monitoring rrogram Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification applicant shall be responsible for securing the services of a qualified archaeologist who shall be present onsite to monitor all remaining grading activities. 4. A qualified archaeologist should be notified and invited to the pregrade meeting to set the controls of observations during grading. After the property is grubbed, but before initial grading begins, areas which could be sensitive should be re -inspected. if archaeological materials are found, their significance should be ascertained and salvage procedures implemented prior to their destruction by grading. 5. The applicant shall inform the City Planning Division and the City Engineer if suspected archaeological or paleontological artifacts are discovered during grading operations. This notification shall occur in writing, within 24 hours of the suspected find. In the written notification, the project manager shall identify the qualified archaeologist who will inspect the find. During grading and construction activities. During grading and construction activities. Department of Community Development. Department of Community Development Review archaeologist's findings. Receipt of notification. 6. If a qualified archaeologist is called upon to During grading and Department of Community Review archaeologist's inspect a suspected find, that professional construction activities. Development findings. will prepare a written report of the significance of the find, including a recommendation(s) for further action, if any. A copy of this report shall be transmitted to the Planning Division within )B109030018.MMP 30 Mitigation Monitoring Program Vesting Tentative Map 47850 Mitigation Measures Timing Responsible Party Verification I week after inspection of the suspected find. PUBLIC SERVICES 1. Prior to issuance of a building permit, the Prior to issuance of a building Department of Public Works Receipt of funds. project applicant shall pay a development permit. fee to the Walnut Valley Unified School District (WVUSD) in accordance with California. Government Code 53080 and the school fees identified by the WVUSD. 2. Irrigation of open areas will be limited to Prior to issuance of an Department of Public Works Field check. that required to establish plants in place. occupancy permit. 3. Homes will employ water conserving Prior to issuance of a building Department of Public Works Plan check and field check. technology which include such features as permit. low -flow shower heads and water -efficient toilets, etc. 4. Site watering during grading activities shall During grading activities. Department of Public Works Field check. use reclaimed water if permitted and available. 5. Landscape plans shall include the selection Prior to issuance of a building Department of Public Works Review landscape plans. of water -efficient plants, wherever possible. permit. JBl09030018.MMP 31 Mitigation Monitoring Program Vesting Tentative Map 47850 RESPONSE TO COMMOM RECEIVED ON DRAFT ENVIRONMENTAL IMPACT REPORT VESTING TRACT MAP NO. 47850 CONDITIONAL USE PUNIX I' NO. SMS OAK TREB PERRO T NO. 89528 SCH NO. 90910505 Applicant: Diamond Bar Associates, Inc. 3480 Torrance Boulevard, Suite 300 Torrance, California 90503 - Contact: Kurt Nelson Prepared for: City of Diamond Bar Community Development Department 21660 East Copley Drive, Suite 190 Diamond Bar, California 91765-4177 . - GDirectoir on�act � DaSlo, ., .. , Prepared by: Michael Brandman Associates 173 f0 Red Hill Avenue, Suite 35O Irvine, California 92714 Contact: Thomas E. Smith, Jr-., AICP March 1995 March 29. 1995 TABLE OF CONTENTS Section Pa¢e A INTRODUCTION ............................. A-1 B LIST OF RESPONDENTS ....................... B-1 C RESPONSES TO WRITTEN COMMENTS ............. C-1 D RESPONSES TO PUBLIC TESTIMONY .............. D-1 ApRendices A Comment Letters B. Geotechnical Response Letters from Leighton and Associates, Inc. and Harrington Geotechnical Engineering, Inc. 09030018.RTC i Table of Contents March 29, 1995 SECTION A INTRODUCTION Vesting Tract Map (VTM) No. 47850 proposes the development of a 57 custom lot subdivision for custom homes on a 73 acre site in the City of Diamond Bar. The project site is generally located at Steeple Chase Lane and Wagon Train Lane, in "The Country" area of Diamond Bar. The site is located within the Tonner Canyon Significant Ecological Area (SEA). A revised draft environmental impact report (revised DEIR) was released for public review on February 2, 1995. The 30 -day public comment period was extended by the City to March 15, 1995. Seven (7) letters commenting on the revised DEIR were received by the City. This document contains responses to the written comments received during the public review period and responses to comments on the revised draft EIR that were raised at a public meeting that was held on March 11, 1995 to reintroduce the VTM 47850 to community residents. A list of public agencies and private individuals commenting on the revised DEIR is provided in Section B. An attendance list for the March 11 meeting is provided in Section D. The comment letters received by the City of Diamond Bar are contained in Appendix A and responses to all comments are contained in Section C of this document. 09030018.RTC A-1 Introduction March 29. 1995 SECTION B LIST OF RESPONDENTS The following agencies, individuals, and organizations provided written comments on the revised Draft EIR for VTM 47850: Agencies 1. Governor's Office of Planning and Research — March 3, 1995 2. California Department of Transportation (Caltrans) -- February 15, 1995 3. County Sanitation Districts of Los Angeles County -- February 16, 1995 Individuals 4. Frances Drum -- February 25, 1995 5. Inez and Luis Weiss — February 28, 1995 6. Wilbur Smith -- March 14, 1995 Organizations 7. Diamond Bar Associates -- March 13, 1995 0903001&.RTC B-1 List of Respondents March 29. 1995 SECTION C RESPONSES TO WRITTEN COMMENTS Governor's Office of Planning and Research Michael Chiriatti, Jr., Chief, State Clearinghouse March 3, 1995 Response OPR-1: This letter is the standard response from the State, transmitting comments from reviewing agencies on a draft EIR. No response is necessary. 2. California Department of Transportation, Office of Advance Planning Wilford Melton, Senior Transportation Planner February 15, 1995 Response DOT -1: No response is necessary. County Sanitation Districts of Los Angeles County Financial Planning & Property Management Section Marie L. Pagenkopp, Engineering Technician February 16, 1995. Response CSD -1: Comment noted. Use of these generation rates reduces the wastewater volume anticipated from the site from 19,950 gallons (350 gallons per home per day) as noted in the revised draft EIR to 14,820 gallons (260 gallons per home per day). The revised sewage generation rates and volumes are hereby incorporated into paragraph 3 of page I-10 in the revised draft EIR. Response CSD -2: Comment noted. Should the City Council approve the proposed project, the applicant will initiate annexation proceedings into District No. 21. The applicant will comply with all applicable CSD requirements and pay connection fees in effect at the time of application for annexation for sewer service. Response CSD -3: Comment noted. The proposed project conforms to the Diamond Bar General Plan, and as such, is consistent with the SCAG Growth Management element of the 1994 Regional Comprehensive Plan. Available and planned capacities of the Districts' facilities should therefore be able to accommodate the sewage flows from the proposed project. 09030018.RTC C-1 Responses to Written Comments March 29 1995 4. Frances Drum Diamond Bar Resident February 25, 1995 Response Drum -1: Comment noted. The 57 lots proposed in VTM 47850 have been analyzed for potential environmental impacts in the revised draft EIR and in the original draft EIR. While approval of this project would add incrementally to impacts on traffic, air quality, and schools, the EIR determines that these effects can be mitigated to acceptable levels. Response Drum -2: The traffic impacts from the proposed 57 lots were evaluated in the draft EIR for VTM 47850. After mitigation, traffic impacts were determined to not be significant. 5. Inez and Luis Weiss Diamond Bar Residents February 28, 1995 Response Weiss -1: Comment noted. A notice concerning a public meeting on VTM 47850 set for March 11, 1995 was mailed to you and your neighbors in late February. The attendance list from the meeting is provided in Section D. Response Weiss -2: Unforeseen circumstances do sometimes arise during project construction. City staff monitors all projects developed in the City to insure conformance with City Council direction, approved plans, and mitigation measures. Should project changes be needed to address unforeseen conditions, staff will evaluate such changes to insure compliance with applicable City standards and environmental requirements. Response Weiss -3: The revised draft EIR (page A-18) notes that Cooper's hawks have been reported in the past in Tonner Canyon and reported an observation of one Cooper's hawk onsite during the EIR surveys. No nests were observed. While project development will remove most existing habitat, the expansive acreage in the Tonner Canyon SEA (over 4,800 acres) will continue to provide adequate habitat for the Cooper's hawks and other raptors that may use the project site to forage. Response Weiss -4: Comment noted. Current views of the project site will be affected by project development. It should be noted that the VTM 47850 site has been planned for residential development at the proposed intensity in each version of the Diamond Bar General Plan, as well as in the County's general plan for the area prior to incorporation. Response Weiss -5: The traffic impacts from the proposed 57 lots were analyzed in the original draft EIR, and with mitigation, were not found to be significant. As noted above, the Diamond Bar General Plan has anticipated development on this site for many years and has provided for its traffic contribution in traffic and circulation planning for this area. The proposed project will not receive access from Hawkwood, although a gated access for emergency vehicles (fire) will be provided at the terminus of Hawkwood. All primary access to the site will occur from two points on Steeple Chase Lane. Construction traffic will also access the site from Steeple Chase. 09030018.RTC C-2 Responses to Written Comments March 29, 1995 Response Weiss -6: The grading plan for the site has been designed using landform and contour grading techniques. The grading for the referenced development is occurring in the unincorporated County area west of the 57 Freeway and is not using a landform/contour grading approach. A much more natural appearance of the project site from adjacent areas will result from the use of these techniques. When the revegetation of the site is complete, it will blend into the adjacent hillsides. 6. Wilbur Smith Diamond Bar Resident March 14, 1995 Response Smith -1: Comment noted. Specific responses to comments in Attachment B of Mr. Smith's letter are provided below. Responses from the applicant's and the City's geotechnical engineers are contained in Appendix B and incorporated into the following responses. Response Smith -2: Comment noted. The comment is not an environmental issue. Response Smith -3: Comment noted. Specific responses to the elements of this comment are provided below. The geotechnical reports associated with the development of Tract 47850 have been reviewed by Leighton and Associates. During the review process, comments were prepared by Leighton and Associates regarding various aspects of the geotechnical report. The review comments were subsequently responded to by the developer's geotechnical consultants, Harrington Geotechnical Engineering, Inc. Through an iterative process involving our review of the responses to our comments, preparation of additional review comments and subsequent responses to those comments by Harrington, all geotechnical issues were resolved. On August 23, 1994, Leighton approved Tract 47850 from a geotechnical standpoint. It is Leighton's opinion that the geotechnical issues associated with the development of Tract 47850 have been adequately addressed. The following is a relatively brief layman's translation of the 24 questions raised and answered in the review process. The original questions and answers, with full texts of all reports, are on file with the City of Diamond Bar. 1. The original Harrington report indicated that site "colluvium" (loose, surficial material that has been moved over time through erosion) had been mapped. Leighton requested that these surface soils be shown on the geotechnical maps, and this was done on revisions submitted to the City. Leighton asked how Harrington had determined these areas for mapping, and the answer was that the locations were determined through topographical maps, aerial photographs, and actual field inspection. 2. Leighton requested that all "geologic structures" be shown on the geologic maps of the site, including "anticlines," "synclines" and "faults". Anticlines are upward undulations of the horizontal beds of soil beneath the surface. Synclines are undulations downward, and faults are essentially any interruption of this pattern. These structures had already been mapped in a 09030019.RTC C-3 Responses to Written Comments March 29, 1995 number of site cross-sections, but in response to the request, the maps were revised so that all geologic structures were shown in every section. 3. Leighton asked for the location of two borings on the site which were referred to in the reports. The two sites in question were borings performed by "Lawmaster", the geological firm who had previously performed testing on the site. Although Jim Evans, the field engineer for Harrington, had worked for Lawmaster on the site, and the data derived was thought to be accurate, the precise location of these borings could not be determined. Therefore, this data was not utilized or relied upon in the reports. 4. Leighton asked for the basis in Harrington's showing a "syncline" (downward undulation of bedding material) on five sections of the geologic maps submitted. Leighton believed that more borings to increased depth were necessary to support these conclusions. In response, Harrington went back to the site and performed additional boring to greater depths. The sections were revised based upon the additional information thus gathered. No differences were significant enough to warrant changes in the grading plans. 5. Leighton pointed out that one geologic cross section submitted by Harrington seemed to contradict another. The data was revised to correct the discrepancy, and proposed depth of fill material was adjusted accordingly. 6. Leighton asked Harrington to describe the physical characteristics (grain size, thickness of bed, moisture content, etc.) of beds of material onsite thought at the time to be "Bentonite", a type of clay. Leighton also requested that further, deep boring be performed onsite to confirm the location of this material on the site. Bentonite is a weak clay which presents potential problems in stabilizing a building site, since assumptions concerning the soil's resistance to possible movement, or "shear strength", must be conservative where this material occurs. Harrington's engineers had pointed out the suspected presence of the bentonite in their reports, assumed that it occurred in continuations of bedding planes, and allowed for its presence (both proven and assumed due to topography) in strength parameters and calculations used to derive conclusions and remedial grading recommendations. In response to Leighton's inquiry, Harrington collected samples of the material from the site. These samples were analyzed by independent laboratories, including the New Mexico Bureau of Mines and Mineral Resources. It turned out that the material was in fact not bentonite, but rather "smectite", a silty soil material of similar appearance but greater strength than bentonite. The physical characteristics of the material were given to Leighton, and the requested deep borings, plus considerable bulldozer trenching, were performed to establish were it occurred. Despite the fact that the material was determined to be smectite, the strength parameters attributed to it and utilized in calculating site conditions and remedial grading were similar to those associated with the weaker bentonite. This was done to be conservative in arriving at conclusions about the site and remedial grading recommendations. 7. Leighton asked about the stability of the temporary slope to be created while removing an old landslide from the site. While this was a question of temporary, construction period conditions rather than a factor in determining building site stability, the safety of the crews and anyone else present during grading was a concern. The requested calculations were performed, and the factor of safety was found to be sufficient. 0%30018.RTC C-4 Responses to Written Comments March 29, 1995 8. Leighton asked for an explanation of several mapping symbols and terminology used by Harrington in the report. Harrington provided this information. 9. Leighton asked for either additional deep boring along the west canyon at the site, or alternatively, that remedial grading be designed to stabilize the area. This was done. 10. Leighton requested that additional deep borings be performed on the eastern ridge, in order to substantiate the geologic structures shown for the area. This was performed to Leighton's satisfaction, and the additional data collected was incorporated into the report. 11. The earlier Lawmaster soils report indicated more extensive historic land movement in the area of Lot 9 than shown in the updated Harrington report. Harrington pointed out that Lawmaster's own borings in the area, as well as Harrington's own data, contradicted this conclusion. Leighton was satisfied that the Harrington mapping was sufficient for pre - construction delineation of the area in question. If conditions were found to be otherwise during grading operations, adjustments will be made. 12. Leighton asked for further information on the stability of the sewer pump station slope areas. This was provided, with re -analysis of the site, and as a result, a stabilizing shear key will be graded in this area. 13. Leighton asked that small, interior slope areas likely to require stabilizing grading be specifically identified, and that subdrains (drains placed to prevent water intrusion into fill areas) also be shown. This was done. 14. Leighton asked for the removal depths of proposed fills in areas of three lots. This information was provided. 15. Leighton asked for the stability factor of the temporary slopes which would be created during installation of a shear key (a wedge of compacted, stable soils used to stabilize an existing area). See question and answer No. 7 above for further detail. These calculations were performed conservatively, and the factor of safety was more thanadequate. 16. Leighton asked that all remedial earthwork be shown on the final grading plans, and this was done. 17. Leighton asked that a line be drawn on the tentative map which would show the outer edges of remedial grading. This was done. 18 & 19. Leighton asked for the rationale and basis of strength parameters utilized for the material previously thought to be bentonite, and for other clay beds on the site. As previously indicated, the material thought to be bentonite was determined to be smectite, a stronger material, and the physical strength determinations were made through actual lab testing of the material. However, Leighton was concerned with assuring that calculations were made on a conservative basis, to provide for even a "worst-case" scenario. Therefore, Harrington and Diamond Bar Associates agreed to use lesser shear strength parameters, as if the material had actually been the weaker bentonite, in determining the factor of safety for the building sites. 0903001BATl c C-5 Responses to Written Comments March 29, 1995 20. Leighton asked that one of the geologic cross sections containing a potential trouble area be reanalyzed, using two different potential failure areas. This was done, and both conclusions resulted in sufficient factors of safety. 21. Leighton asked that another geologic section be reanalyzed to assume a different subsurface condition. This was done, and the factors of safety were still sufficient. 22. Leighton asked that a potential area of instability be reanalyzed with difference assumptions of subsurface soils bedding angle that those indicated in the Harrington report, in order to determine if the factor of safety for this area would still be sufficient. The requested reanalysis and calculations were performed, and the factor of safety was still sufficient. 23. Leighton requested that additional analysis as to slope stability be performed in a geologic section which could potentially be affected by fill in the central canyon. Such analysis was performed, utilizing conservative strength parameters. The resulting factors of safety were still sufficient. 24. Leighton asked for stability analysis of geologic section E -E at depths below the level of the remedial grading, in order to show that the depth of the planned shear key was sufficient. This was done, and shear key depth was increased by 10 feet to provide an even greater factor of safety. Response Smith -4: Comment noted. The assumption that there will be no static ground water table or phreatic surface which would create pore pressures within the subject slopes is a valid assumption. Shear keys will be constructed around the perimeter of the site which will be drained and effectively prevent the buildup of water. It is, however, likely that the materials onsite will undergo fluctuations in moisture content. Strength parameters developed for the earth materials onsite, including the smectite layer, were based on saturated conditions. Thus, it is our opinion that the analyses performed to evaluate the stability of the site are appropriate. Response Smith -5: Comment noted. In order to mitigate the potential effect of downhill bedrock creep on the development, a series of daylight shear keys will be constructed around the perimeter of the development. In effect, the creep -affected material will be removed in the vicinity of the shear keys and replaced with compacted fill. To reduce the potential for water accumulating in the shear keys, drains have been incorporated in the design. Also, all lots will be capped with compacted fill to reduce the potential for surface water infiltration. In our opinion, these measures are state -of -the -practice and adequately address the drainage issues associated with stabilization of the slopes onsite. Response Smith -6: Comment noted. The City of Diamond Bar and the County of Los Angeles require a minimum static factor of safety of 1.5 when analyzing the stability of permanent manufactured and natural slopes. This is also an industry standard. Tract 47850 has been designed such that all slopes meet the minimum required stability standards. Factors of safety are calculated for slope areas not on a lot by lot basis. If a slope exceeds a factor of safety greater than 1.5, all lots adjacent to that slope will have a factor greater than 1.5. Response Smith -7: Comment noted. As with most hillside developments, the most significant geotechnical issues with respect to the development of Tract 47850, are those associated with 0903001SATC C-6 Responses to Written Comments March 29, 1995 slope stability. The smectite layers onsite were considered by Harrington as the material which controlled the site stability. Harrington conducted numerous laboratory tests to determine the strength of this material, both in house and by others. Based on the results of their testing program, they established strength parameters for the smectite material. However, based on our review of the geologic units onsite and on our experience, we questioned (by review comment) whether other, weaker materials could be present onsite. After several discussions, Harrington agreed to reduce the strength parameters to those which they had originally assumed, based on the assumption that the controlling material onsite was a weaker clay material. Slope stability analyses were performed for the site utilizing the weaker strength parameters. Based on the analyses, shear keys were designed to stabilize the perimeter slopes. The construction of drains within the shear keys and capping of lots with compacted fill are measures taken to reduce the potential for water buildup within the shear keys, as discussed in our response to comment D. Burrowing animals can have a detrimental effect on the surficial stability of slopes. The future homeowners, or the homeowner's association, should develop a slope maintenance program, one aspect of which should be the control of burrowing animals. 7. Diamond Bar Associates Craig Weber & Associates March 10, 1995 Response DBA -1: Comment noted. Response DBA -2: Comment noted. The 24" and 36" box trees can be purchased and do not have to be contract grown. They must be of the same type as those lost to development. Response DBA -3: It is necessary to use acorns collected onsite to contract grow replacement trees. Size diversity is also necessary when replanting to match, to the degree possible, the natural condition of the site before development. Confining all replacement trees to a single size at planting will not recreate the size diversity present in the natural -condition. It should be noted that survival rate of transplants is dependent on stock quality, length of time in container or box, and maintenance. Response DBA -4: The basis for a 50 foot vs. 15 foot clearing zone relates to the sensitivity of oak woodlands. As a community which includes understory vegetation and related habitat, oak woodlands are more sensitive than individual oak trees. The 50 foot clearing zone will provide appropriate protection for the oak woodland habitat areas onsite. Response DBA -5: Comment noted. Landscaping within buffer zones shall be limited to native plants; other plants are suitable for private lots. The first sentence of mitigation measure 26 on page A-33 of the revised draft EIR is hereby revised to read as follows: Landscaping within common areas and buffer zones shall be restricted to the use of native plants. 09030019.RTC C-7 Responses to Written Comments March 29, 1995 A new sentence is hereby added at the end of mitigation measure 26 on page A-33 of the revised draft EIR: Landscaping on private lots may use non-native plants. Response DBA -6: Comment noted. Michael Brandman Associates, the City's environmental consultant that prepared the revised draft EIR, prepared the conceptual plan referenced in mitigation measure 29. Response DBA -7: Comment noted. Opuntia spp. and Baccharis "Twin Peaks" are hereby added to the first complete paragraph on page A-34 of the revised draft EIR. Response DBA -8: Comment noted. The following plants are hereby added to the Floral Compendium in Attachment A to Appendix A of the revised draft EIR. Calochortus spp. Calystegia macrostegia Keckiella cordifolia Marah macrocarpus Paeonia californica Stipa spp. 09030018.RTC C-8 Responses to Written Comments March 29, 1995 SECTION D RESPONSES TO PUBLIC TESTIMONY A public workshop was held on March 11, 1995 to reintroduce the VTM 47850 project to interested members of the community and to provide an opportunity to ask questions of the applicant, his consultants, and City representatives. Fourteen (14) residents attended the meeting including one City Council membtr and two Planning Commissioners. A list of meeting attendees is presented at the end of this section. A summary of attendee comments on the revised draft EIR and responses is presented below. Comment 1: Is there any agency that has jurisdiction over biological resources onsite? Response: Yes, the City has the final authority over the mitigation measures to be adopted into the project for impacts to biological resources onsite. The EIR also notes that a permit may be required from the Army Corps of Engineers and the California Department of Fish and Game prior to issuance of the City's grading permit for drainages that would be impacted by project grading. Comment 2: Was the biological resources investigation accomplished over an extended timeframe to insure the most complete inventory of onsite plant species? Response: The biological resources onsite were surveyed initially in 1990-91 by the applicant's consultant, and on three occasions between October and December 1994 by MBA biologists. While this is not the optimal survey window to obtain an exhaustive species inventory, the surveys did permit a habitat characterization analysis for species not detectable and sensitive. Using past experience and the California Natural Diversity Data Base, the City's environmental consultant determined that suitable habitat for sensitive species occurring in the region is not present onsite. Comment 3: How will the City insure that the replacement trees specified in the EIR mitigation measures will be viable over time? Response: The mitigation measures in the EIR require that all replacement trees and habitat located onsite and at offsite locations be monitored for a 5 year period after planting. The 5 year requirement is used by the California Department of Fish and Game, as well as the U.S. Fish and Wildlife Service for their mitigation programs. Thereafter, it is assumed that the trees will have become naturalized and will remain viable in the site environment. Comment 4: Have the traffic and school impacts from the project been considered in the EIR? Response: The revised draft EIR lists the mitigation measures for identified impacts to roads and schools that were analyzed in the Draft EIR that the Diamond Bar Planning Commission had recommended to the City Council for certification in late 1991. Mitigation measures for the incremental, but not significant, impacts of project traffic were recommended. These included 09030018ATC D-1 Responses to Public Testimony March 29 1995 fair share contribution to roadway improvements along Diamond Bar Boulevard (most of which have already been completed) as well as sidewalks on the eastside of Diamond Bar Boulevard across from the Country Hills Shopping Center. While determined to not be significant, impacts to the schools within the Walnut Valley Unified School District are mitigated through payment of the required school fees to the District. At present, these fees are set by state law at $1.73 per square foot of living area. 09030018.RTC D-2 Responses to Public Testimony rch 11, 1995 Public Meeting QE c w i LAc LIKA" J 90M -sm I L /r1411.1l1 �. d . C,�r,•�er, I017q Hueki4elce4s 3.0- gziu I Flay 3'KAFA�2 swoop J a ,CAOCL �.fv M lCi� 7�llyv�fibl/ �35oci�7Pj 6�tAt6 w�� >YSi�31 710 ry/o .79 qb zSo— SSs�4� 19oy-req-68Z age-- s6-( •s-7L�, S�Y�w f'z� /93SNl�.Aa �lgS�,.,,f-S„d;N��/y) �37-3� .� OA -ft -J, c, 4z6105, V, ww . 3ZC3 FmIa,_ a"e IID( 8L!- ! iy3 7� ��- GC►ca jo �� vq� �,PAr � 'o, A. f'h u/c 1► - /3,e ,,¢ w,� �� • �� o - �� / S� D-3 -'r * OArE - Yc/S G.,41 ,e q70- -514 It 0-S14cc —} 4e&f LM—' 7 March 29, 1995 Appendix A STATE OF CALIFORNIA PETE WILSON, Govemor GOVERNOR'S OFFICE OF PLANNING AWJW@k IIINITY 1400 TENTH STREET 1 �f:Vr ' '"X -NIT SACRAMENTO, CA 95814 F ;''? 13 Fti is 29 March 3, 1995 ROB SEARCY CITY OF DIAMOND BAR 21660 COPLEY DRIVE, SUITE 190 DIAMOND BAR, CA 91765-4177 Subject: OT 89583/TR 47851 SCH #: 90010505 Dear ROB SEARCY: The State Clearinghouse has submitted the above named draft Environmental Impact Report (EIR) to selected state agencies for review. The review period is now closed and the comments from the responding agency(ies) is(are) enclosed. On the enclosed Notice of Completion form you will note that the Clearinghouse has checked the agencies that have commented. Please review the Notice of Completion to ensure that your comment package is complete. If the comment package is not in order, please notify the State Clearinghouse immediately. Remember to refer to the project's eight -digit State Clearinghouse number so that we may respond promptly. Please note that Section 21104 of the California Public Resources Code required that: "a responsible agency or other public agency shall only make substantive comments regarding those activities involved in a project which are within an area of expertise of the agency or which are required to be carried out or approved by the agency." Commenting agencies are also required by this section to support their comments with specific documentation. These comments are forwarded for your use in preparing your final EIR. Should you need more information or clarification, we recommend that you contact the commenting agency(ies). This letter acknowledges that you have complied with the State Clearinghouse review requirements for draft environmental documents, pursuant to the California Environmental Quality Act. Please contact Mark Goss at (916) 445-0613 if you have any questions regarding the environmental review process. Since el , Michael Chiriatti,J . Chief, State Clearinghouse Enclosures CC: Resources Agency OPR-1 STATE OF G AND TRANSFGRTATION AGENCY FETE M«� C1O� DEPARTMENT OF TRANSPORTATION DISTRICT 7. 120 SO. SPMNG SI. LOS AHMES. G 90012- 606 TDO (21 3) M7-6610 Ab James DeSefano City of Diamond Bar 21660 East Copley Drive Suite 100 Diamond Bar, California 91765-4177 Dear Mr. DeSefano, February 15, 1995 IGR/CEQA 1047 Tentative Tract Map # 47850 SCH /90010505 Vic: LA -57-R3.17 Thanks for including the Department of transportation in the environmental process for this project. We see no impact to the State Transportation System by the construction of the 57 units included in Tentative Tract Map #47850. At this point we have no further comments. cc: State Clearinghouse 1400 Tenth Street Sacramento, California 95814 Sincerely (klWnW 91snod By Wilford Melton Senior Transportation Planner IGR/CEQA Coordinator Office of Advance Planning I die G`�C�L1 N11`—NJSM SS AND TRANSPORTATION A064CY PETE WLsad, Co....*, DEPARTMENT OF TRANSPORTATION DISTRICT 7, 120 So. SPWJG ST. LOS AWAM, CA 90012.7606 TDO (213) W-6610 • February 15, 1995 IGR/CEQA 1047 Tentative Tract Map # 47850 SCH #90010505 Vic: LA -57-R3.17 James DeSef ano City of Diamond Bar 21660 East Copley Drive Suite 100 Diamond Bar, California 91765-4177 Dear Mr. DeSefano, Thanks for including the Department of transportation in the environmental process for this project. We see no impact to the State Transportation System by the construction of the 57 units included in Tentative Tract Map DOT -1 147850. At this point we have no further comments. Sincerely Wilford elton Senior ansportation Planner IGR/CEQA Coordinator Office of Advance Planning cc: State Clearinghouse MASTI WATEN KMAMA"ft •cue WA..a ul. v' to t COUNTY SANITATHODISTRICTS OF LOS ANGELES COUNTY 1955 Workman Mill Road, Whittier, CA 90601-1400 Mailing Ad rs sc P.O. Box 4998, Whittier, CA 90607-4998 Teleptone: RM) 699-7411, FAX: (310) 695-6139 JO N W ti+ m 7 Lu tom+.. uw c v � S oc James DeStefano Community Development Director City of Diamond Bar 21660 Copley Drive, Suite 100 Diamond Bar, CA 917654177 Dear Mr. DeStefano: CHARLES W. CARRY Chief Engineer and General Manager February 16, 1995 File No: 21-00.04-00 Vel Tentative Tract Man No. 47850 The County Sanitation Districts received a Revised Draft: Environmental Impact Report for the subject project on January 31, 1995. We offer the following correction to the Draft E13L • Sewer Service. pace 1-10. The second sentence of this paragraph should read as follows: The proposed project would generate approximately Q gallons per day (57 homes that each generate CSD -1 an average of gallons per day). We offer the following mitigation measures to the Draft EIR: • The area in question is outside the jurisdictional boundaries of the Sanitation Districts and will require annexation into District No. 21 before sewerage service can be provided to the proposed development. For specific information regarding the annexation procedure and fees, please contact Ms. Alma Horvath at (310) 699-7411, extension 2708. • The Sanitation Districts are empowered by the California Health and Safety Code to charge a fee for the privilege of connecting (directly or indirectly) to the Sanitation Districts' CSD -2 Sewerage System or increasing the existing strength and/or quantity of wastewater attributable to a par icWar parcel or operation already connected. This connection fee is required to construct an incremental expansion of the Sewerage System to accommodate the proposed project which will mitigate the impact of this project on the present Sewerage System. Payment of a connection fee will be required before a permit to connect to the sewer is issued. We offer the following comment to the Draft EIR: • The design capacity of Districts' wastewater treatment facilities are based on population forecasts adopted in the Southern California Association of Governments' (SLAG) 1994 CSD -3 Regional Comprehensive Plan (RCP). The RCP is in the process of being adopted as part of the 1994 South Coast Air Quality Management Plan (AQMP). The AQMP is jointly James DeStefano 2 February 16, 1995 prepared by the South Coast Air Quality Management District (SCAQMD) and SLAG as a requirement of the Federal Clean Air Act (CAA). In order to conform with the AQMP, all expansions of Districts' facilities must be sized and service. phased in a manner which will consistent with the Growth Management element of the 1994 RCP. The Growth Management element contains a regional growth forecast for the counties of Los Angeles, Orange, San Bernardino, Riverside, Ventura, and Imperial which was prepared by SLAG. Specific policies included in the RCP which deal with the management of growth will be incorporated into the AQMP strategies to improve air quality in the South Coast Air Basin. The available capacity of Districts' treatment facilities will, therefore, be limited to levels associated with approved growth identified in the adopted RCP. As such, this letter does not constitute a guarantee of wastewater service, but is to advise you that the Districts intend to provide this service up ts the levels which are legally permitted and to inform you of the currently existing capacity any proposed expansion of Districts' facilities. If you have any questions, please contact the undersigned at (310) 699-7411, extension 2717. Very truly yours, Charles W. Carry 4eA�,,W4�*o L Pagenkopp Engineering Technician Financial Planning & Property Management Section MLP1.1 N:1EN V/SSW1D!VAS521Tr-47MLTA CSD -3 RECEIVED COMMUNITY n�rrr^nCnT �3 P11 12. 07 February 25, 1995 James DeStefano Community Development Director City of Diamond Bar 21660 East Copley Drive, Suite 100 Diamond Bar, CA 91765-4177 Mr. DeStefano, I have reviewed the revised draft of the Environmental Impact Report concerning VTM 47850. I am writing because I oppose the development of this lot. Diamond Bar has many homes available for anyone to purchase without adding more homes and destroying another hillside and the natural habitat. Two lots (VTM 48487 and VTM Drum -1 45851) have already been approved for development of homes and the Townhome complex on Golden Springs near Diamond Bar Boulevard is near completion. These developments alone are going to affect our Community with the added traffic congestion, air quality and the impact on our schools. Diamond Bar has always been known for its Country atmosphere and Country living. This is being destroyed with destruction of our Drum -2 hillsides, to many homes, and the congestion of traffic. Diamond Bar is becoming another over -populated city in Los Angeles County. As a resident of Diamond Bar (The Village of Diamond Ridge) for the past sixteen (16) years, we have seen many changes and our hope is that the Planning Commission, the City Council and all of the community that is involved would stop and re-evaluate the development of another hillside in our City. Please, let us try to maintain a portion of our Country Living. Your time to read this letter will be greatly appreciated. Sincerely, Frances Drum 3364 S. Falcon Ridge Road Diamond Bar RECEIVEO COMMUNITY _7 P.1 5: 21 City of Diamond Bar 21660 East Copley Drive, Suite 100 Diamond Bar, CA 91765-4177 Dear Mr. DeStefano: Mr. & Mrs Luis Weiss 3358 Falcon Ridge Road Diamond Bar, CA 91765 February 28, 1995 Att: James DeStefano, Community Development Director Ret: Revised Draft EIR VTM 47850 My husband and I reside in the Diamond Ridge development. To be more exact, we live on Falcon Ridge in a home overlooking the area of the proposed development. We have had a chance to read the Revised Draft, Environmental Impact Report, VestingTentative Map 47850 dated January 1995. We learned about the revised proposal, to build on this property, after we came back from vacation and our neighbor happen to mention it. We learned she had received a copy of the Revised Draft because of her participation at one of the City Councils meetings, three years ago, when this development proposal was being presented during a public council meeting. If not for her, we would have not been aware that this development, which we thought had been denied back in `92, was again being submitted for possible approval. I will venture to say, after talking to some of our neighbors, that a large number of residents around this area are not aware of what is about to happen regarding this project. To this date we have not received any letter or notice of the upcoming deadline to submitt comments or complaints, to you, regarding this project. Chances are there will not be too much advanced notice, if any, of the next public meeting at which time a presentation to the City Council of the new proposed Revised Draft will be made. In regards to the plan for Vesting Tentative Map 47850, we have reason to be concerned with the development of the hill behind our home. These are some of our concerns: 1. It is my feeling, based on past experience, that regardless of what the applicants for this permit to develop this site have stated on their proposal, there will always be changes to the original proposal once the project is underway. Unforseable situations can come up, and usually do, that will require modifications to the originally approved plan. These modifications could be detrimental to the residents in this area. An Weiss -1 Weiss -2 example of an unforseable situation could be, where more of the hill might have to be carved up, for whatever reason, well into the project. At that time there will be no choice but to cavy out this action if the project is to move forward. Well, this action will create more damage to the environment. More natural drainage areas will be altered which will cause soil erosion, etc. 2. The environmental impact to the wildlife we now enjoy will be significant. For example we know, because we see them from time to time, that there are Falcons Weiss -3 and hawks nesting on trees on and around that hill. The habitat of these and many other animals that we now enjoy will be destroyed. 3. The view and privacy that we paid extra to have will be greatly compromised. Our home as well as many of the homes that overlook the canyon on Falcon Ridge, Weiss -4 will stand to loose a portion of their value. 4. Furthermore, the traffic congestion that already exists because this city was not originally planned for its current building density, will get much worse. Right now it takes me about 15 minutes to drive from Pathfinder to Grand Avenue between the hours of 4 and 5 PM. How much worse is it going to get ? I would also like to mention that I see the strong possiblity of Hawkwood being opened through to that area, sometime in Weiss -5 the future, to accommodate traffic generated by the owners of these proposed homes in the country. Or upon project approval, to allow construction equipment access to that area. This would be intolerable. 5. In regards to the grading of the hill and the pads, every day when I drive down to Cold Springs it is very visible to me what has been done to the hills, where grading is currently underway by Arciero Brothers, in the southern end of Diamond Bar Blvd. It reminds me of what this beautiful, pristine canyon is going to look like when construction Weiss -6 preparations are underway. It also predicts the amount of dust and noise we are going to be subjected to. All these concerns are very real to us. The Main reason we moved to Diamond Bar in 1984 was its good reputation for being one of the few areas left that had little traffic congestion, low crime, beautifull green hills, and at the same time was relatively close to Los Angeles. Well, the city is still close to Los Angeles, however everything else is no longer true. This city has almost no green areas left, every possible open site has been built on or is on the block to be built on, crime has gone up because the density has increased tremendously and the traffic is horrible. But the building continues....... For once I would like to see a decision made for the good of the many instead of the few who only care about the revenue they can put in their pockets. Sincerer, Ines L iu s Weiss Wilbur G. Smith 21630 Fairwind Lane Diamond Bar Ca. 91765 March 14,1995 To: City of Diamond Bar 21660 East Copley Drive Diamond Bar'Ca. 91765 RECEIVED CO�IMUNITY r 15 F11 2: 25 Attn: Mayor P.Papen,City Council Members,J.DeStefano Subject: Vesting Tentative Track Map 47850 Ladies and Gentlemen: Information (Attachment A) suppilied by the Cities Community Development and Engineering Departments has been reviewed for the purposes of providing citizen comment at Public Hearings to be held on the Crystal Ridge Development (VTTM 47850)'and its Draft Environmental Inpact Report (Ref.5). Attachment B presents my citizen comments on the subject that I will present at these hearings and requests for actions to be to by the City Council before voting on approval of the VTTM 47850. Please include this letter with attachments A and B in the final documentation of the Public Hearings. Thank You Wilbur G. Smith mith-1 ATTACHMENT A REFERENCES 1) Supplemental Geotechnical Investigation and Geotechnical Report Review Response for Subject Project, Dated April 28, 1994 by Harrington Geotechnical Engineering,Inc. 2) Supplemental Geotechnical Investigation and Grading Plan Review, Dated October 16,1992 by Harrington Engineering Inc. 3) Geotechnical Review Sheet for VTTM 47850, Dated October 29, 1992 by Leighton & Associates Inc. 4) Compilation of Geotechnical Report Review Sheets and Responses for Vesting Tentative Track 47850 dated August 29,1994 by Harrington Geotechnical Engineering Inc. 5) Revised Draft Environmental Impact Report for Vesting Tentative Map 47850 Vol 1 and 2 dated January 1995 by Michael Brandman Associates. ATTACHMENT B COMENTS and ACTIONS REQUESTED OF THE CITY COUNCIL BEFORE APPROVAL OF TRACK 47850 A) Direct the city attorney to give a legal opinion on the liability (degree and time periods) of D.B.A., City of Smith -2 Diamond Bar and J.C.0 for losses incurred by homeowners due to geologic hazards or errors in geotechnical calculations or assumptions. B) Reference 3 contains 24 specific questions that Leighton and Associates asked regarding Track 47850. These questions were elements in the law suite filled by D.B.A against the city. D.B.A. responded to these questions in Reference 1. The city should now direct Leighton to make a definitive statement on each of the responses as to its adequacy , Leightons acceptance of the response and also its relevance to the current design. C) Stability analysis calculations are not adequate because they assume no groundwater and/or pore water pressure (Ref. 1 page 11). This assumption is not valid because it is physically possible for w water to reach the smectite layer. To support this,Section 4.4 (Analysis of the Smectite Layer),page 10 states "other factors Smith -4 such as different topography and/or ground water buildup must also have existed at the time of failure and contributed to the slides". A clear contradiction exists here. Page 11 states no water, whereas page 10 indicates the existence of ground water buildup in the past. Therefore the Council should require that all stability analysis and Factor of Safety calculations are made with assumptions of finite amounts of groundwater and/or pore water pressure. D) Another deficiency in the reports is that Reference 2 (page 10) identifies a condition of bedrock creep (to depth of 100 ft.) paused by 1) cyclic changes in moisture content .and density due to seasonal wetting and drying, 2) water in tension/shrinkage cracks, ...., 4) deep-seated,very thin bentonite (smectite) bed. However,Ref.2 page 11 states " ground water was not encountered in any of the excavations made at the site and is not expected to be a matter of future concern to the project under normal conditions ....." .It is not reasonable to assume that because water was not encountered in these excavations that in will not occur at some future time, especially since there is evidence Smith -5 (land slides) that water was there in the past. Also the NO GROUNDWATER statement is qualified by NORMAL CONDITIONS. Analysis presented in these documents which vitally effects the fortunes and lives of so many people certainly should consider abnormal conditions such as adverse weather (50-100 year rainy seasons),uncertainties in geologic parameters, human deficiences in workmanship etc.,etc. The city council should require D.B.A. to conduct an error analysis of the Factor of Safety and other stability analysis computations using reasonable uncertainties in all system parameters (presence/amount of water,efficiency of subdrains, geologic parameters. etc.,etc.) J E) The COUNTY BUILDING CODE requires slope Factors of Safety greater than 1.5. The references presented Factors of Safety values of 1.5051, 1.5039, 1.5011, 1.5133, 1.5218,1.5602 ,1.6092. These values indicate that the tract design is very marginal from the COUNTY Factor of Safety prespective. Small errors in the computational process,the data used or assumptions made could cause many of these values to be less than the requirement which means the project would not be safe by County standards. The City Council should require D.B.A. to conduct an error analysis of the Factor of Safety computational process . Also the Council should require D.B.A to publish the Factor of Safety for each lot. F) The most significant aspect of Track 47850 is the presence of a smectite layer which lies from 30 to 100 ft. below the surface. If water reaches this layer earth movement could occur. Existing landslides are evidence of this . The developers approach to preventing this is to ; 1) Place 10 or 3 ft. earth blankets on each lot to prevent - Smith -6 the infiltration of surface water down to the smectite layer. JJ Smith -7 2) The use of subdrains. I Unforunately the developer presents no analysis of the effectiveness of these measures. He strongly recommends that the homeowner eradicate borrowing animals from blanket fills because their tunnels provide easy passage for water to the lower depths. The City Council should require D.B.A. to find pest control professionals who will state the degree to which borrowing animals can be controlled in areas that are adjecent to much larger wilderness areas (such as Tonner Canyon) where no attempt is made to control them. Also D.B.A. should be required to make calculations on the effectiveness of the blanket fills. Smith -7 I RECEIVED 33/14 18:41 1995 AT 969-861-3117 PACE 1 (PRINTED PAGE 1) 1 JCC DEVELOPMENT ID: MAR 14'95 18:10 No.013 P.01 JCC HOMES U80 TOR&%= NYM SU171L 300 MKRAr" G 90103 f10 610.3990 orms 310 3mnu fAX .J V7 Number of Pages (Including this page)$ 4 T o : �.n �O�,I fl G.•�r o �'st�nxs Ls � •'s�.�a /.�1� Fax Number) l Al 3//7 PhcMc N --u .6rs 109- 3fL S!7(o F r o m e 4, y%• — cel l' 4fle:'a" ALn C RECEIVED 83/14 18:41 19% AT JCC DEVELOPMENT March 13, 1995 909-861-3117 PAGE 2 (PRINTED PAGE 2) 1 ID: MAR 14'95 18:10 No.013 P.02 City of Diamond Bar Mr. Jim DeStefano, Director of Community Development 21660 E. Copley Drive, Ste. 190 Diamond Bar, CA 91765 Re: Revised Draft EIR for VTM 47850, 'Michael Brandman & Associates Comments from Diamond Bar Associates Dear Jim, Our comments on the above referenced document are limited the attached letter of March 10, 1995, from our landscape Craig Weber & Associates. Sa�� Kurt Nelson Diamond Bar Associates DIAMOND BAR A890 DIATES, INC. 3480 Torrance orra 3Blvd., SjU 54x3990301, yonr�, 316-7133 3390 to those in consultants, DBA -1 ( RECEIVED 83/14 18:92 19% AT 989-861-3117 PAGE 3 (PRINTED PAGE MA 3) 14' 95 JCC DEVELOPMENT ID: LANDSCAPE ARCHITECTURE CNNK C1 M 10 March 1995 JCC Monies 3480 Torrance Boulevard, Sulte 300 Torrance, California 90503 Re: Comments Revised Draft EnWrona*ntal impact Report Traci 47850, Diamond Bar 18:10 No.013 P.03 1. it will be difficult, if not impossible, to contract grow oak trees to a 24' box or 38" box size within a period df one to two years. 2. We recommend planting oak trees from a 15 gallon container. 3. It has been recognized In the Landscape Industry that a 15 gallon plana will be larger and healthier alter fhre (5) years of growth than If that plant was Installed from a 24" or 3W box container. PM A-32, 21 1. What Is the basis for a 50' clearing zone vs. a 151 clearing zone? 1. The. language is too restrictive. 2. We recommend that all common area sbpes on the perimeter of the sibs grading be reetrfcbed to native plants. 3. Private Ions should not be restricted to native plants. This conforms to what has already been approved for Tracts 47851 b 48487. 790 REDONDO MIE.. (ANG KACI L G 9OW4 M(340)A38-3464 PAS KX 1377. NEWPORY BEACH. CA 92663 PH. (714) 660.2761 DBA -2 DBA -3 DBA -4 DBA -5 C RECEIVED 83/14 18:42 JCC DEVELOPMENT 199s AT 999-861-3117 PAGE 4 (PRINTED PAGE 4) 1 ID: MAR 14'95 18:11 1!0.013 P.04 ego A-33_29 ��p�,�,o Bt � DBA -6 . 1. •�h �bW tN T %al BtOar PIW? 2. Low foal volume plant should indude Opwft spp. and Bao~s 'Twin DBA -7 Peaks,' both of which haw beer► spedtted for Tract 47861 & 48487. Flora and Fauns CmDenk The foNowing plant have been obsemed on site and should be Included In the oonvendis: C'Ia DBA -8 m Keoklelia oordtfolta Mash macrocarpus Paeonla oaNtOrntoa Stipa spp. March 29, 1995 Appendix B MPR -29-•95 WED 10:18 ID:CITY OF DIAD BAR TEL h1D:714-861-3117 tt984 P02 z« Ava�%" '" .--- city of vAmood Bar 21660 &A CoPkY DUM Suite 190 Diamond Bay Calik aia 917M ML Geon Who EHG� DEQ OR Nm 29101640 swrOm - .--JL —'lReRM=t0a&=Cbqm=fsRevrft Trod 47854 C9 of Diamond Bar, C,ahfarnia In renpoose to hwkdesyour request000=00, lire helve VCvkvW the k = dated '"N*14,1993. b7 WWMa Smith Ow 10POUBCS NO Unwed ooctapood>n8 � comments A ���� th% lata it X97 attached. A. lois mount ahowd be directed to the at7 Adorery. B. T= 8aoteehnienl tePOM associated with the development of Thet 47850 hm been teviewed by J.ei& n and Aro«•tes Deft the review Prooea. oommCna wen prepared by X,eghton and A..bl s tai ferrous rp°ts of the gw*ichmcal rdport MW rmriow thvespoodedto b7 the devdopees ycotechnecd com ui ma, Hw&0= 000106"ka' to our Comments, an iteradv�e pro«na iewoiv tbon oar revlerr dee gaga � of additional rcviw commms niorpent �p°O� comments by HAT&PMaqrmoawkdiaoes. wo reaoivcd. On Aagust 23,19%, app,.d 'had 47850 frees a aeataehdW StaadpoiM. It is our opinion that the gcote &,ical ivies associated with the devicelopment of Tract 47850 have bees auquate4 addressed. G 1Le a "mptlon that awe wAl be no static Vmmid water tabic or phrewtia surface which would crate Pm Presa M within the subject I" is a valid m=Wdan. Shear keys v,3I,,- a msuucmd around the: palaww of the sit which wM be drained and e>iiootiv* prewea buildup of wase: It is, how w- h't *that the mMedais onsite wM att bxp &m6atioes in waistm ao "OL Streaph pa .WW, gaped for the earth M%Uials aatite, U dudint the mee to yya, were based on sab wd caaditim& 'Ilius, it is our oploiou that the JWAh►M pwkcmai to evaluate the liability of the site are: appraprlate- D. In order to mitrpte the potential effect of dowahiii bedrock creep on t� �Ia of daylight shear r will be eoattrviceed nand the pe offt �r� lC with Cffects the creep-ai%eted aaterLi w� be remoMed m the l IN VOW _ the shear WY16 r" b m compactedn= 5d. To roduoe: the Ab all bis w0l be capped with compacted fl 10 beea ;neocponted in the daiga Also, &W WA CAN ON ROAD, SUITE 4, WALNUT, CALIFORNIA U.S.A. 41789 RM 869-M - IBM M2286 FAX P" 869.6387 MAR -29-195 WED 10:18 ID:CITY OF DIAMOND BAR TEL NO:714-861-3117. #984 P03 291016460 per' tial fm surface water inmtratim In our Opinion. thole meastaes aie :tatOOf'tb0-�CadbG __ _ q g* address the derinaee issues associated with wbilliatioa of the dopes ondte, Ii The atp of Diamond Bar and the County of La Angeles �m :minty of 130 when amlyv2ng the aabft of permanent and natural SIDPOL Mds Is also an industry wndae+d. Tract 47850 has been dm;pod DO& that all abpes 000 *6 mWomism ragaured dabOy standards. P As wlth oral hillside da etlopments, the soon dgttiecaat geotedtnicd issues with trapeet to the dowk9mertt of Tired ASM aro dxw assoei W with slope A"q- The saetsite lays anile wm oond&xad by Hacdnpon as the oaudd which ambollcd the site dAtYt>: Har tion aonduaW nometon labonmq uo to dtoeratlne the shangtb of" materi4 both in house and by others. Based on the resells OEM& tasting progam, they ahbli:ited st:atgth paramam ftx the smadte mawrhL However, bond on our review of the geologic mite aodte and OR eta aaperianoe, we; questioned (by n xiew e=MM) whethw otba, weals mstaci* a mW be p muM ondte. After w wal &wumiow, Harrtngtm agreed to reduce the stratph pwmwt rs to those which they had orWaWiy assumed. based an the astnmp = that the controlling material onsite .vas a .pedrer day material Slope stabi{ity analyses were pajormod for the site utUiring the weaker str'cagth parameters. Based as the analyses. sites* keys ware designed to 9"M20 the perrmcta dopes. MW wastrucdots of drains widds the shear b* and capping of IOU with compacted B am mcawres taken to redox the poemdW hoc water buildup wkhin the shear kcya. as discussed In ata response to Comment a Dw=. g =mob = bave a detrimental effect on the sur5cid stability of slopes. The fntmti bomeowaas, or thishomeowmes saoeiaMM should develop a dope maintcaaooe program, one aspect of which should be the control of bwwowiog animals. If 7m have any qucatj=4Please can us at your cornenienoe. Respeetfuny submitted, LIIGHTON AND ASSOCEATIM INC David G Smitb, RCE 46722 Manager of Operations Attachment Letter dated March 14,1993 (R&" w iLaIR G. sA 1 rev-) rn -2. 0 MAR -29-'95 I,ED 10:19 ID:CITY OF DIAMOND BAR TEL hO:714-861-3117 #994 PO4 RECEIVED COQ NIMITY iT Wilbur G. smith " ::' 15 Pi 2= 25 21630 Fairwind Lane Diisond Bar Ca. 91765 March 14,1995 To: City of Diamond Bar 21660 East Copley Drive Diamond Bar ca. 91765 Attn: Mayor P.Papen,City Council Members,J.DeStefaao Subjects Vesting Tentative Track Map 47850 Ladies and Gentlemens Information (Attachmentt-A) suppilied by the Cities Cc®nnity Development and Engineering Departments has been reviewed for the purposes of providing citizen comment at Public Hearings to be held on the Crystal Ridge Development (VT= 47850) and its Draft Environmental Inpact Report (Ref - 5) -Attachment B presents my citizen comments on the subject that I gill present.at these hearings and requests for actions to be taken by the City Council before voting on approval of the VTTM 47850. Please include this letter with attachments A and B in the final documentation of the Public Hearings. Thank You w�-L/•� Wilbur G. Smith MPR -29-195 WED 10:20 ID:CITY OF DIAMOND BAR TEL NO:7i4-861-3117 #984 P05 - ATTACHM ST A 1) Supplemental Geotechnical Investigation and Geotechnical Report Review Response for Subject project, Dated April 28, 1994 by Barrington Geotechnical Engineering,Inc. 2) Supplemental Geotechnical Investigation and Grading Plan Review, Dated October 16,1992 by Harrington Engineering Inc. 3) Geotechnical Review Sheet for VTTM 47650, Dated October 29• 1992 by Leighton i associates Inc. 4) Compilation of Geotechnical Report Review Sheets and Responses for Vesting Tentative Track 47650 dated August 29,1994 by Harrington Geotechnical Engineering Inc. 5) Revised Draft Environmental Impact Report for Vesting Tentative Map•47850 Vol 1 and 2 dated January 1995 by Michael erandman Associates. 11 MAR -29-195 6ED 10:20 ID:CITY OF DIAMOND BAR TEL ND:714-861-3117 #964 P06 ATTWT B COMM" and ACTIONS REQUESTED CF TBB CITY COUNCIL BBFORB APPROVAL OF TRACK 47850 A) Direct the city attorney to give a legal opinion on the liability (degree and time periods) of D.B.A., City of Diamond Aar and J•C.0 for losses incurred by homeowners due to geologic hazards or errors in geotechnical calculations or assumptions. B) Reference 3 contains 24 specific questions that Leighton and Associates asked regarding 'Track 47850. These questions were elements in the law suite filled by D.B.A against the City. D.B.A. responded to these questions in Reference 1. The city should now direct Leighton to make a definitive statement on each of the responses as to its adequacy , Leightons acceptance of the response and also its relevance to the current design. C) Stability analysis calculations are not adequate because they assume no groundwater and/or pore water pressure (Ref. 1 page 11). This assumption is not valid because it is physically possible for w water to reach the smectite layer. To support this,Section 4.4 (Analysis of the Smectits Layer),page 10 states 'other factors such as different topography and/or ground water buildup must also have existed at the time of failure and contributed to the slides". A clear contradiction exists here. page 11•8tatss no water, whereas page 10 indicates the existence of ground water buildup in the past. Therefore the Council should require that all _ MAR -29-195 WED 10:21 ID:CITY OF DIAMOND BAR TEL ND:714-861-3117 tt9B4 P07 stability analysis and• •Paotor -mf -Safes wa-1 uistions -&-a -made with awwuw.etion� ..r r:..: 1..- w........1.. ..r snd/e! pnrw water pressure. D) another deficiency in the reports is that Reference T (page 10) identifies a condition of bedrock creep (to depth of 100 ft.) caused by 1) cyclic changes in moisture content and density due to seasonal matting and drying, 2) water in tension/shrinkage cracks, ...., 4) deep-seated,very thin bentonite (smectite) bed. 8owever,Ref.2 page 11 states " ground water was not encountered Ln any of the excavations side at the site and is not expected to be a matter of future concern to the project under normal conditions .It is not reasonable to assume that because water was not encountered in these excavations that in will not occur at some future tine, especially since there is evidence (land slides) that water was there in the past. Also the NO CRO[J1KMTER statement is qualified by NoamL CONDITIONS. Analysis presented in these documents which vitally effects the fortunes and lives of so many people certainly should consider abnormal conditions such as adverse weather (50-100 year rainy seasons),uncertainties in geologic parameters, human deficienees in workmanship etc.,etc. The city council should require D.H.A. to conduct an error analysis of the Factor of Safety and other stability analysis C=Iputations using reasonable uncertainties in all system parameters (presence/amount of wator,efficiency of subdrains► geologic parameters. etc.,etc.) MAR -29-195 WED 10:22 1D:CITY OF DIAMOND BAR TEL N0:714-861-3117 #984 POB B) The COUNTY BUILDING CODE requires slope Factors of Safety greater than I.S. The references presented Factors of Safety values of 1.5051, 1.5039, 1.5011, 1.5133, 1.5218,1.5602 ,1.6092. These values *indicate that the tract design is wry marginal from the COUETr Factor of safety prospective. Small errors in the computational procesepthe data used or assumptions made could cause many of these values to be less than the requirement which means the project would not be safe by County standards. The City Council should require D.B.A. to conduct an error analysis of the Factor of Safety computational process . Also the Council should require D.S1.A to publish the Factor of Safety for each lot. F) The most significant aspect of Track 47830 is the presence of a smectite layer which lies from 30 to 100 ft. below the surface. If water reaches this layer earth -movement could occur. Existing landslides are evidence of this . The developers approach to preventing this is to i 1) place 10 or 3 ft. 'earth blankets on each lot to prevent the infiltr�#Iion of surface water down to the smectits layer. 2) The ase of-subdrains. Unforunately the developer presents no analysis of the effectiveness of these measures. He strongly recommends that the homeowner eradicate borrowing animals from blanket fills because their tunnels provide easy passage for water to the lower depths. MAR -29-'96 WED 10:22 ID:CITY OF DIAMOND BAR TEL NO:714-861-3117 #984 P09 The City Council should require D.B.A. to find pest control professionals who rill state the degree to which borrowinq auinals can be controlled in areas that are adjeosnt to much larger wilderness areas (such as Tonner Canyon) where no attempt is made to-contral then. Also D.B.A. should be required to make calculations on the effectiveness of the blanket fills. MAR -29-995 6ED 11:26 ID:CITY OF DIAMOND BAR TEL IO:714-861-3117 4987 P01 1 RECEIVED CQMIMITY DEM OMBIT Sys 1F:R 2 7 A M 9: ab Overview Questions Gootechnical Review f byLalghton a Associates Responses by Harrington Geotechnical In processing a subdivision such as Tentative Tract 47850, one of the most important matters is the Investi- gation of the site's geology by the developer's geotechnical consultants, and review of that data by the City's consultants. in order to assure proper and safe developrant, extensive research and testing of the geology of the site was performed by Harrington Geotechnical,ggBologic and soils consultants to Dlaefond Bar Associates. .919 investigation utilized both Information frog previous investigations and extensive now data gathered by Harrington, including tests of numerous soils and bedrock samples taken frog above and below the site surface. Conclusions were drawn and grading plans developed using state of the art techniques, including computer assisted variable calculations and other technology unavailable a short tlue ago. The City of Diamond Bar's geotechnical consultants, Leighton i Associates, reviewed the geological reports In order to assure that conclusions were accurate and had been arrived at conservatively. This process Included review of the Geology and Soils report of October 15, 1992, resulting In 24 questions which set forth the remaining concerns about site geology. These questions were answered through written reports and correspondence between Harrington and Leighton over a period of many Months. In providing these answers, even more was learned about the site through further, physical Investigation and reanalysis of data. The new Information was used In revised calculations utilizing conservative strength paramfeters and varied Interpretations of site conditions. The soils and geology for Tract 47850 were only approved when Leighton i Assoclates•and the City engineers were satisfied with all responses, calculations ions and remedial grading proposals. In plain terms, in app the geology of this site, a great deal of information was collected and conservatively applied, anticipating many Nworst-case" scenarios. Weak soils (or even suspected areas of weakness) will be entirely removed and replaced or else buttressed with strong, compacted fills, and yet the grading will be done in such a planner that the natural beauty of the site will be preserved. The following is a relatively brief, layman's translation of the 24 questions raised and answered In the review process. The original questions and answers, with full texts of all reports, are on file with the City of Dlanond Bar. (1) MAR -29-' 954ED 10:32. I D : C [ P( OF DIC I'gND , EAR . �, N10.714 -06t -.X117,_...- . 09-CIS..?� .. PA .♦ 1. The ori inai Harrington report indicated that site "coiluvlurn" loose, surflcial material that has been moved over time through erosion) had been mapped. Leighton requested that these surface soils be shown ori the geo- technical gaps, and this was done on revisions submitted to the City. Leighton asked how Harrington had determined those areas for mapping, and the answer• was that the location; were determined through topographical maps, aerial photographs, and actual field inspection. 2. Leighton requested that *all "geologic structures" be shown on the geologic claps of the site, including "anticlines,* `synclines" and "faults." Anticlines are upward undulations of the horizontal beds of soil beneath the surface. Synclines are undulations downward, and faults are essentially any Interruption of this pattern. These structures had already been mapped In a number of site cross-sections, but in response to the request, the maps were revised so that all geologic structures were shown In every section. 3. Leighton asked for the location of two borings on the site which were referred to in the reports. The two sites In question were borings" performed by 8Lawmaster," the geological firm who had previously performed testing on the site. Although Jim Evans, the field engineer for Harrington, had worked for Lavaoster on the site, and the data derived was thought• to be accurate, the precise location of these borings could not be determined. Therefore, this data was not utilized or relied upon in the reports. 4. . Leighton asked for the basis in Harrington's showing a "syncline" (downward undulation of bedding material) on five sections of the geologic maps submitted. Lelghton belleved that more borings to increased depth were necessary 'to support these conclusions. In response, Harrington went back to the site and performed additional boring to greater depths. The sections were revised based upon the additional Information thus gathered. No differences were significant enough to warrant changes In the grading plans. S. Leighton pointed out that one geologic cross section submit ad- by Harrington seemed to contradict another. The data was revised to correct the discrepancy, and proposed depth of fill material was adjusted accordingly. 6. Leighton asked Harrington to describe the physical characteristics (grain size, thickness of bed, moisture content, etc.) of beds of material onsite thought at the time to be "Bentonite," a type of -clay. Leighton also requested that further, deep boring be performed onsite to confirm the location of this material on the site. Bentonite (2) - }-9% LED 10:23 ID:CITY.IF DIAMOND BAR..TEL ND:714-861-3117, #984 P1 Is a weak clay which presents potential problems In stabilizing a building site, since assutptions concerning the soil's resistance to possible movement,- or "shear strength," must be conservative where this material occurs. Warrington's engineers had pointed out the suspected presence of the bentonite in their reports, assumed that it occurred in continuations of bedding planes, and allowed for its presence (both proven and assumed due to topography) in strength parameters and calculations used to derive conclusions and remedial grading recommendations. in response to Lotghton'a inquiry, Harrington collected sawples of the material from the site. These samples were analyzed by independent laboratories, including the New Mexico Bureau of Mines and Mineral Resources. It turned out that the material was In fact'not bentonite, but rather esnwctite,0 reaver silty soil material : of similar appearance but 9 strength than bentonite. The physical characteristics of the material were given to Leighton, and the requested deep borings, plus considerable bulldozer trenching, were performed to astablish'where it occurred. Despite the fact that the material was determined to be snlectite, the strength parameters attributed to it and utilized In calculating site conditions and remedial gradEng were slMllar to those associated with the weaker bentonite. Thls was done to the site andbe conservative in remedIaI gradIng*recrconclusions about oisamOdatIOns 7. Leighton asked about the stability of the temporary slope to be created while renloving an old landslide from the site. While this was a question of temporary, construction period conditions rather than a factor in determining building site stability, the safety of the crews and anyone also present during grading was a concern.. The requested calculations were performed, and the factor of safety was found to be sufficient. S. Leighton asked for an explanation of several napping symbols and terminology used by Harrington In the report. Harrington provided this Information. 9. Leighton asked for either additional deep boring along gthe radingWest becanyon designedthe to stabilizeatherarea. Thisthat wasremedial lal done. g 10. Leighton requested that additional deep borings be performed on the eastern ridge, in order to substantiate the geologic structures shown for the area. This was parfodat te to Leighton's satisfaction, and the additional data collected.was Incorporated into the report. 11. The earlier Lawmaster soils report indicated more extensive historic land movement In the area of lot 9 than shown In the updated Harrington report. Harrington pointed out that Lawmaster's own borings in the area, as well as (3) MAR -29-195 WED 10:31. I D :CITY OF DIAMOND BAR TEL x0: 714-861-3117 , , , #9e5 P'02 Herrington'_s _own data, contradicted this conclusion. Leighton was satisfC�d.�.ffiat the Hartington niavging was sufficlent for pre -construction ddlineation of UOU arced In question. operatlons�dad)ustirents wlllfound beobe otherwise during 9 Rade 12. Leighton asked for further Information on the stability of the sewer punip station slope areas. This was provided, with re -analysis of the site, and as a result,.a stabilizing shear key will be graded in this area. 13. . Leighton asked that small, interior slope areas likely to require. stabilizinl-grading be specifically Identified, � Into flii that ob nals(drains shplaced Thlsprevent don�ter intrusion l Leighton the removal This information depths for ionwas proposed fills provided. 151. Leighton asked for the stability factor of the tem- porary slopes which would be created during Installation of a shear key (a wedge of compacted, stable soils used to stabilize an existing area). See question and answer No. 7 .above for further detail. These calculations were performed conservatively, and the factor of safety was more than adequate. 16. Leighton asked that athis wasdone. elearthwork be shown on the final grading plans, 17whichLeighton wouldasked showthat the outerline edgesdrawn tentative remedialgrading. rrla p This was done. 18 it 19. Leighton asked for the rationale and basis of strength parameters utilized for the material previously thought to be bentonite, and for other clay beds on the site. A5 prev Indicated, the material thought to be bentonite was determined to be sMectlte, a stronger material, and the physical strength determinations were made through actual lab testing of the material. However, Leighton was concerned with assuring that calculations were made on a conservative basis, to provide for even a "worst-case" scenario. Therefore. Harrington and Diamond Bar Associates agreed to use lesser shear strength paramters. as If the.l hader In deteretiningteritheafactoraofusafetyeforctally benttheweabulildingnsite3'nitE 20. Leighton asked that one of the geologic cross sections containing a potential trouble area be reanalyzed, using two different potential fallure areas. This was done, and both conclusions resulted In sufficient factors of safety. 21. Leighton asked that another geologic section be re - (4) MAR -29-' 95 I.ED 10:24 I D :,CITY . OF, DIAMOND BAR TEL NO : 714-861-3117 11964 P12 ^ �^- analyzed to assume a different subsurface condit'lon. This was done, and the factors of safety were still sufficient. 22. Leighton asked that a potential area of instability be reanalyzed with different assumptions of subsurface soils bedding angle than those Indicated In the Harrington report, in order to determine if the factor of safety for this' area would still -be sufficient. The requested reanalysis -and calculations were performed, and the factor of safety was still sufficient. 23. Leighton requested that additional analysis as to slope stability be performed in a geologic section which could - potentially be affected by fill In the central canyon. Such analysis was perforaed, utilizing conservative strength. parameters. The resulting factors of safety were still sufficient. 24. Leighton asked for stability analysis of geologic section E -E at depths below the level of the remedial grading, In order to show that the depth of the planned shear key was sufficient. This was done, and shear key depth was Increased by 10 feet to provide an even greater factor of safety. (5) Rob Sear; City of pi Via Facsll, Re: Over, and r, Geolot Dear Rob, nd gar to (909) 661-3117 ..4:28 No.010 P.02 March 29, 1885 Of '�nses4 question Haran rnments by Lei ?X Solis Report of ton GeoteChnical 9hton $Associates October, 1992 concerning Tra ct 47850 This letter is YOU requested nctent Provide the 9 questions No.further detail No. 5 . d 12. and background The i' "r which by Marrin section of canyon a Ston i :iced the two of the geola In response silo i different ase of the historic 'sass se s sub to Of ctron mitred noted, efghton,s (approxi dsllde in and reels,ons drawnComment, the mate 20 the central at the intersect,on of hwhich data was reyiewet. discrepancy). adjusted to accurately ptaCed the reflet,t the cone d, the mistake the rwo cross-sections. area cansistentl No, correction. Fill depth Was y ConservatRemedial grading was also which scenario, rather designed might or might not excuse relying o r this area to No. se the need f more borin reflect the more 12 -The shear key or same 9 to provide a Part of Y for data the remedial stabllitatio n Of grading pian for the the sewer Pump mp station area is DIgM01yp 3480 ems -r, a (21 B 5q .IS - TESD IIyC x3990 . FAX (2 3)' 6 71 3 - 3CC DEVELOPMENT 1D: MAR 31'95 14:28 No.010 P.03 Mr. Rob Searcy, City of Diamond Bar 3-29-95, page 2 Please let me know if you would like further detail on any of the other questions. I've tried to strike a balance in this "translation" whereby laymen can understand the principals without having to spend a great deal of time becoming educated in the details. We would of course be happy to provide more detailed information to anyone who is interested, Sincerel , Kurt eison Diamond Bar Associates TYPICAL SECTION PRIVATE {TREET LOT INFO EASEMEN 10 o©` A Development of DIAMOND BAR ASSOCIATES, INC. LANDSCAPE MITIGATIO TRACT 47850 Prepared By CRAIG WEBER & ASSOCIATES LANDSCAPE ARCHITECTURE 790 Redondo Avenue Long Beach, CA 90804 213/438-3151 REMAINING VEGETATION PLANT COMMUNITIES ® wsnwwn woaaiun �eoa�mwc�®wean vooasro © wsmow.ruarr woaawo mmiwmxa®wwwrwmdao E �� i cwaru spa F EI881Yp C11.1v�Fe4E vEaEr�non G rurEx�s�ooEsro�um�En owwarEisAevaaEn,vnwa O 8T8EET T8EE8 TRt Es Ex uT sr a EEPEEn-HGeMrt BEEtlES o AnE-Ana�sEEaEs VICINITY MAP DEVELOPER ENGINEER LANDSCAPE ARCHITECT CONCEPTUAL .LANDSCAPE PLAN PROPOSEOI CRY OF .DIAI WATER MANAGEMENT BASIN NO. I WATER MANAGEMENT BASIN NO. 2 WINTER SEASON DRAINAGE C WATER MANAGEMENT BASIN NO. 2 SUMMER SEASON PROPOSED RESU MY OF CONCEPTUAL LANDSCAPE STUDIES DIAIV ORNAMENTAL STREETSCAPE RECONSTRUCTED WALNUT WOODLAND uMOM�oc ccam unc�wr carcccecnm •oroh 111i0EPSfO1R PWR WTFALL RECONSTRUCTED CHAPARRAL —AMORc--_... urccna,art ranMrMuwM.: RECONSTRUCTED.CANYON WOODLAND NATURALIZED DRAINAGE irr,nrwoow.b �� DIAGRAMMATIC SECTION THRU SITE PROPOSED RUMMIAL WW CRY OF CONCEPTUAL .LANDSCAPE STUDIES VIAMON[ COMMENTS on APPROVAL of VTTM 47850 by WILBUR G. SMITH April 6,1995 1) Request City Council to provide written response to letter from W.G.Smith. Both letter and response (with all questions answered) should be inclued in final documentation of these hearings. 2) Reasons for opposition to approval of 47850. a) Engineering documents assume that water will not reach the smectite layer without presenting any evidence to justify this. b) Engineering documents make contradictory statements which cast dought on their credibility. Example: "Groundwater was not encountered in any of theexploratory borings drilled on the site...", where as plates C -11,C -45,C -47,C-48 of Ref 5 Vol II show water and seepage. c) Engineering documents admit that weaker shear strength parameters exist in this area than were used in the Factor of Safety �y calculations. The parameters used in the Weatherfield homes just W-9- of 47850 are less than those used in 47850. d) Recommendations of an independent consult (Douglas E. Moran) to include pore water pressure in factor of safety calculations and to use lower shear strength parameters were ignored. e) The Factors of Safety (1.5051,1.5011,1.5133,1.5103) are marginal relative to the County requirement (1.5) and were based on normal conditions.The Factors of Safety should be much to allow for abnormal conditions such as adverse weather,incorrect assumptions, workmanship, computation errors etc,etc. f) A heavy burden is placed upon the homeowner to eradicate burrowing animals, prevent excessive watering ,maintain pools/spas without cracks/leaks and prevent all surface water infiltration.Otherwise landslides may occur.