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Home My WebLink About105-Attachment D.pdfr -i x� Stormwater Control Plan New Private Access Road 4 Lots -- 20865 Wardell Road Saratoga, California d OCT 2 6 2006 CITY 0F)AlLg7'U(0 'I IA FT^ " ref. +.,r., October 23, 2006 IV-4d--Z-C1V1L F%Imr�'m 1776 Technology drive San Jose, California 951 M Tel (406) 452 -9300 Fax (408) 452 -9301 www.tscivilen_q.com ► 1 ► ► ► r 1 1 1 1 1 1 1 1 1 1 1 Stormwater Control Plan Stormwater Control Plan New Private Access Road 4 Lots — 20865 Wardell Road Saratoga, California 95070 Prepared for: Alok Aggarwal -- Maintenance Director 13645 Lexington Court Saratoga, CA 95070 Prepared by: I FUR - "CIVIL M IWMIN6 1776 Technology Drive San Jose, Califomia 95110 Tel (408) 452 -9300 Fax (408) 452 -9301 www.tscivileng.com October 23, 2006 TABLE OF CONTENTS EXECUTIVE SUMMARY SITE SUMMARY I. Project Setting I.A. Project Description I.B. Existing Site Condition I.C. Opportunities and Constraints for Stormwater Control Site Area Map Notes Drainage Area Ct H. Measures to Limit imperviousness ILA. Measures to Make Development More Compact II.B. Measures to Limit Directly Connected Impervious Area Selection and Preliminary Design of Stormwater Treatment BMPs III.A. General Characteristics of the Treatment Facilities IV. Source Control Measures V. Permitting and Code Compliance Issues VI. BMP Operation and Maintenance VI.A. Means to Finance and Implement BMP Maintenance VI.B. Summary of Maintenance Requirements VII. Certification TABLES TABLE 1 - Existing and Proposed Impervious Coverage TABLE 2 - Sources and Source Control BMPs TABLE 3 - Construction Plan C.3 Checklist FIGURES (in back) FIGURE 1 - Stormwater Planter BMP FIGURE 2 — BMP Exhibit FIGURE 3 — BMP Sizing Worksheet FIGURE 4 — Miscellaneous Background Data Stormwater Control Plan 1 K 2 2 2 3 4 5 6 7 8 8 8 8 8 9 11 11 11 17 13 3 9 -10 12 I 5tormwater Control Plan l EXECUTIVE SUMMARY The subject 7.73 acre site is within the "Hydromodification Management Plan" (HMp) area of the Santa CIara Valley Urban Runoff Pollution Prevention Program. Average slope of the property is approximately 15% and the natural topography makes it impracticable to treat the following three areas. Area X — 2.5 acres that drain northwesterly from Lots C and D to a broad riparian corridor in the Parker Ranch open space, Area Y - 1.3 acres at the northeast of Lot B that drains directly to an on -site swale. Area Z - 0.6 acres of Lot A that is primarily the new private road and too steep for stormwater control. The remaining core 3.3 acres encompass the building sites for each of the four lots. Each lot could be built out to a maximum of 15,000 SF impervious coverage for a total of 60,000 SF. The new private access road would contribute 12,200 SF to the stormwater BMP area. Using the 85th percentile hour rainfall intensity for San Jose and doubling that value to 0.17 inches per hour, then adjusting for mean annual precipitation of 25" at the site, results in a flow to the BMP landscape swales off Q = 0.216 CFS. With a 4' wide landscape swale, this flow, assuming a 5 inch/hour percolation rate, would require approximately 1,090 lineal feet of swale. 440 lineal feet will be implemented and 650 lineal feet will be conditioned upon the lots at Design Review, 1 SITE SUMMARY Stormwater Control Plan The existing 7.73 acre site currently contains 0.28 acres of impervious area including, one house, two barns and driveway pavement. This represents 3.6% impervious coverage. With the addition of the private access road {0.39 ac} and the assumed maximum allowable coverage for each lot of 15,000 SF per zoning (1.22 ac) the total new impervious coverage is 24.6% ((0.28 + .39 + 1.22 0 The net increase in impervious area is therefore 21% or 1.62 acres which must be treated or ��ed through detention and other practical means. I. PROJECT SETTING I.A. Project Description The 20865 Wardell Road project involves the residential development of four new single - family homes and a private access road. The 7.73 acre site is located immediately west of the terminus of Wardell Road lust IOQ' west of the intersection with At de Arguello. There is one small residence of approximately 1,700 SF (which will be replaced) together with a circuitous 10' wide driveway that provides access from Wardell. Although the current access is substandard for even one lot, it will be retained for legal access to the existing Whalen parcel at 20901 Wardell Road. The existing driveway can also be utilized for emergency vehicle access. New tin Y be via a new 20' wide private access road running due w eterlfyrom Wardell Road. new residences will I.B. Existing Site Condition The 7.73 acre site rises from elevation 350 at Wardell Road to 480 at the highest point within Lot D. The site is a sparsely vegetated former apricot orchard that was dry- farmed up until the late 1970's. East and northeast facing slopes of approximately 15.20% are characteristic of the site. Two "blueline" drainage features are noted on the USGS map of the site. The first is a deeply incised, heavily wooded swale along the northwesterly boundary of Lot D, which is part of the Parken Ranch subdivision open space. No drainage or development is proposed that win impact this sensitive riparian ee corridor. The second "stream" begins as an eroded earthen channel approximately 3' wide by 12" l that flows due east along the southerly lines of Lots D and C. p After 250' and at the common corners of Lots C, B, and A, this swale intercepts another draina e course from the southwest with a tributary area of approximately 6.8 acres. The channel is more deeply .incised but still barren of vegetation. After another 200' the channel reaches a maximum cross - section of 6' wide by 3' deep, thereupon it enters a 12" culvert at an old concrete headwall. The channel reappears 60' further downstream and northeasterly where it parallels the existing 20865 residence driveway along the northwest edge of pavement. The channel gradient flattens to less than 10% over the next 400' where it eventually enters a 24" RCP public storm drain system. This system carries drainage from the Verde Moor Ct. cul de sac to a discharge at Calabazas Creek — a SCVWD facility. 2 A A 4 y 1 t Stormwater Control Plan I.C. Opportunities and Constraints for Stormwater Control The proposed access road and individual site developments create opportunities to intercept and control existing sheetflow drainage that would otherwise continue longstanding patterns of soil erosion and sedimentation. The private access road and accompanying interceptor ditches serve to control approximately 3.3 acres of the primary development area of Lots A, B, C, and D (an average of 0.83 ac /lot). These areas are directed toward the access toad which will provide a cross- sloped roadbed that will deposit surface run -off into wide undulating landscape swales. While the roadway longitudinal gradient of swale "A" may be as high as 17 %, intermittent rock /cobble check dams will provide interruption of excess velocity of flow. Ponding will be developed in a cascading fashion at appropriate vertical increments to optimize ponding and infiltration. Landscape swale "B ": is more moderately sloped at approximately 6% average. Areas Y and Z have constraints that impact the ability to control runoff: Area Y.• This area includes the existing residence and driveway on Lot B (approximately 1.3 acres) The existing residence will likely be demolished and a new residence build at the westerly property line with the tributary area to grassy swale "A ". Consequently, existing run -off for this area will be reduced. The small cteek adjacent to the driveway is not proposed to be altered and the discharge to the 24" RCP will be maintained. Ana Z. This area includes the narrow extension (approximately 80' wide) of Lot A to Wardell Road. The area is characterized by generally loose sutficial soils that are not conducive to infiltration. The significant roadway grading in this area is proposed to be retained with drilled pier retaining walls and numerous subdrain dewatering systems. Consequently, this area will be directly tied to the existing public drainage system within Wardell Road. Inlet filters and protection will be implemented at the catch basin at the beginning of the private road where it connects to Wardell Road. 3 TABLE 1 — Existin and Pro losed Im ervious Covera LOT Existing Structure & Max New Existing g Driveway New Access Total New e Total New Driveway Allowable Within Road Impervious Net AC S (15,000 SF) Easement Within (SF) Impervious Easement (SF) A 1,200 13,800 500 11,000 26,500 24,800 0.57 B 5,500 9,500 5,000 3,200 23,200 12,700 0.29 C 0 15,000 0 3,000 18,000 18,000 0.41 D 0 15,000 0 0 15,000 15,000 035 Total 6,700 53,300 5,500 17,200 82,700 70,500 i,62 Acres 0.15 1.22 0.13 0.39 1.89 % of Site 1.62 Area .73 1 '9% 15.8% 1.7% 5.1% 24.6% 21.0% I.C. Opportunities and Constraints for Stormwater Control The proposed access road and individual site developments create opportunities to intercept and control existing sheetflow drainage that would otherwise continue longstanding patterns of soil erosion and sedimentation. The private access road and accompanying interceptor ditches serve to control approximately 3.3 acres of the primary development area of Lots A, B, C, and D (an average of 0.83 ac /lot). These areas are directed toward the access toad which will provide a cross- sloped roadbed that will deposit surface run -off into wide undulating landscape swales. While the roadway longitudinal gradient of swale "A" may be as high as 17 %, intermittent rock /cobble check dams will provide interruption of excess velocity of flow. Ponding will be developed in a cascading fashion at appropriate vertical increments to optimize ponding and infiltration. Landscape swale "B ": is more moderately sloped at approximately 6% average. Areas Y and Z have constraints that impact the ability to control runoff: Area Y.• This area includes the existing residence and driveway on Lot B (approximately 1.3 acres) The existing residence will likely be demolished and a new residence build at the westerly property line with the tributary area to grassy swale "A ". Consequently, existing run -off for this area will be reduced. The small cteek adjacent to the driveway is not proposed to be altered and the discharge to the 24" RCP will be maintained. Ana Z. This area includes the narrow extension (approximately 80' wide) of Lot A to Wardell Road. The area is characterized by generally loose sutficial soils that are not conducive to infiltration. The significant roadway grading in this area is proposed to be retained with drilled pier retaining walls and numerous subdrain dewatering systems. Consequently, this area will be directly tied to the existing public drainage system within Wardell Road. Inlet filters and protection will be implemented at the catch basin at the beginning of the private road where it connects to Wardell Road. 3 9 f 1 .o —CA a v��t tfr Gv 1 i r - l �.•� d ,•,`._ � ^��- fie; r01 i CD LU 1 .o —CA a v��t tfr Gv 1 p�aP �e Gape 'I ❑1Swc'k i r - l p�aP �e Gape 'I ❑1Swc'k Prepared 6y Srereaphnfogrommefric. ,Ufethads - r . RCAV ENGIN.S.-RS, INC, CO'Wffiflf Civil Engineers 144• Kitnae,& Avar., control by FRANK PISA NO a ASSOCIArES, ci.il, . 'VhgIqeVrs 333 North 261b Son Joss, Calif. Dote of Photography, February M 16e-64 SHEEP 2S,'3'W Mb, fL / oil IN S U urrlrrurrr�u VIWnLJrryV IV ilao. 1. PRIOR TO THE COMMENCEMENT OF ANY EARTHWORK /GRADING ACTIVITIES, THE PERMITEE SHALL ARRANGE A PRE - CONSTRUCTION MEETING. THE MEETING SHALL INCLUDE THE CITY GRADNG INSPECTOR (4C8)868 -1201, f� THE GRADING CONTRACTOR AND THE PROJECT SOILS ENGINEER. THE PERMITTEE OR REPRESENTATIVE SHALL ARRANGE THE PRE - CONSTRUCTION MEETING AT LEAST 48 HOURS PRIOR TO THE START OF ANY EARTHWORK /GRADING ACTIVITIES. 1 I - 2 APPROVAL OF THIS PLAN APPLIES ONLY TO THE EXCAVATION, 1 �- PLACEMENT. AND COMPACTION OF NATURAL EARTH MATERIALS. Rs5 APPROVAL DOES NOT CONFER ANY RIGHTS OF ENTRY TO EITHER PUBLIC - - // -•. PROPERTY OR THE PRIVATE PROPERTY OF OTHERS, APPROVAL OF THIS PLAN ALSO DOES NOT CONSTITUTE APPROVAL OF ANY IMPROVEMENTS. ANY PROPOSED iMPROVEMENTS ARE SUBJECT T4 REVIEW AND APPROVAL BY THE RESPONSIBLE AUTHORITIES AND ALL OTHER PERMITS /APPROVALS SHALL BE OBTAINED. 3. IT SHALL BE THE RESPONSIBILITY OF THE PERMITTEE TO IDENTIFY, J, +' / ` 46�4o LOCATE. AND PROTECT ALL UNDERGROUND FACILITIES. 4. THE PERMITTEE SHALL MAINTAIN ALL STREETS, SIDEWALKS AND ALL I ' T' OTHER PUBLIC RIGHTS -CF -WAY IN A CLEAN, SAFE AND USABLE CONDITION. .•'k'ti ',� / ; ALL SPELLS OF SOIL. RACK OR CONSTRUCTION DEBRIS SHALL BE REMOVED x 1 I FROM PUBLIC PROPERTY. ALL ADJACENT PRCPERIY, BOTH PUBLIC AND PRIVATE, SHALL BE MAINTAINED IN A CLEAN, SAFE AND USABLE CONDITION., 5. ALL GRADING SHALL BE PERFORMED IN SUCH A MANNER AS TO COMPLY WITH THE STANDARDS ESTABLISHED BY THE AIR QUALITY MAINTENANCE DISTRICT FOR AIRBORNE PARTICULATES & ALL KNOWN WATER WELL LOCATIONS ON 511E SHALL BE MAINTAINED OR �' °` (- 7 .• -t O 6- 57- 003': N ABANDONED ACCORDING TO CURRENT REGULATIONS ADMINISTERED BY THE w. `- ' " %� 1:488 ACRE 1 I SANTA CLARA VALLEY WATER DISTRICT. CALL (408)265 -2600 EXT, 2660 70 ARRANGE FOR DISTRICT OBSERVATION OF WELL ABANDONMENT. 7. THIS PLAN DOES NOT APPROVE THE REMOVAL OF ANY TREES APPROPRIATE TREE REMOVAL PERMITS SHALL BE OBTAINED FROM THE COMMUNITY DEVELOPMENT DEPARTMENT. ANY REQUIRED TREE PROTECTION i/ Y MEASURES SHALL BE MAINTAINED THROUGHOUT CONSTRUCTION. B THE PROJECT CIVIL ENGINEER, TSCIVIL ENGINEERING, INC. 1776 - w' I - TECHNOLOGY DRIVE SAN JOSE, CA 9511C, HAS DESIGNED THIS PROJECT TO COMPLY WITH THE RECOMMENDATIONS PREPARED BY TERRASLARCH, DATED MARCH 2006. S. ALL GRADING AND EARTHWORK SHALL CONFORM TO APPROVED PLANS AND SPECIRCATIONS IN THE GEOTECHNICAL AND GEOLAGICAL ASSESSMENT I � /pyj `�i • �, "� ` �t!.� 1 II - p DATED MARCH 20, 2406, PROJECT N0. 11COLG. ALL GRADING AND '{ ! '1LJ/.'%• [� I. ;LOS: �. / EARTHWORK ACTIVITIES SHALL BE OBSERVED AND APPROVED BY THE SOILS ENGINEER, TERRASEARCH, 322 PIERCY ROAD, SAN JOSE. CA 95138, i / "..APN' l9a ACRE (408)362 -4920, PRIOR TO ANY GRADING OR EARTHWORK ACTIVITIES. }( UNOBSERVED OR UNAPPROVED WORK SHALL BE REMOVED AND REPLACED " / _ r UNDER OBSERVATION OF THE PROJECT SOILS ENGINEER. * ;1 i S0. ALL. CONSTRUCTION SITES ARE TO BE WINTERIZED WTH APPROPRIATE % /' �.;^j - A. EROSION CONTROL MEASURES IN PLACE FROM OCTOBER 15TH 70 APRIL ,.� 15TH OF EACH YEAR. 11. GRADING ACTIVITIES ARE ONLY ALLOWED MONDAY THROUGH FRIDAY, 7:30 AM TO 6:00 PM. 12. NO CONSTRUCTION MATERIAL, £OUIPMENT, PORTABLE TOILETS, TRASH F��/ / -'- &0 CONTAINERS, ON DEBRIS SHALL BE PLACED IN THE PUBLIC RIGHT -OF -WAY. - �m.eT' _ - �y ° 'M��Fls"T T 13 A TRASH CONTAINER SHALL BE MAINTAINED ON SVTE AT ALL TIMES �' '1 '_'� - 'T .r „*• i wl =4�' r ... �. AND DEBRIS ON SITE WHICH COULD OTHERWISE BLOW AWAY, SHALL BE 4xu REGULARLY COLLECTED AND PLACED IN CONTAINER, 14. ALL CONSTRUCTION DEBRIS (WOOD SCRAPS AND OTHER DEBRIS, WHICH ! + "%f MA.RIDON CANNOT BLOW AWAY) SHALL BE PILED WITHIN THE PROPERTY LINES OF THE PROJECT IN A NEAT AND SAFE MANNER. 15. THE PROJECT SHALL HAVE A SIGN VIEWABLE FROM THE PUBLIC STREET - -^',� ,r•� ,I ,` +� \ THAT INDICATES THE HOURS OF CONSTRUCTION AS. MONDAY - FRIDAY FROM 7:30 AM TO 8:00 PM, SATURDAYS FROM 9:00 AM TO 5:00 PM. ;�' r - y•^�! L� -,. -- 16. OBTAIN AN ENCROACHMENT PERMIT FROM PUBLIC WORKS PRIOR TO THE START OF ANY ROADWAY APPROACH GEMOL171CN OR CONSTRUCTION AT THE CITY STREET. CONTACT PUBLIC WORKS ENGINEER, MACEDONIO NUNEZ. AT (408)668 -1218 FOR INFORMATION REGARDING OBTAINING AN ENCROACHMENT PERMIT. 17. PRIOR TO REQUESTING A FOUNDATION INSPECTION BY THE CITY, THE I f GEOTECHNICAL ENGINEER OR CIVIL ENGINEER WHO PREPARED THE SOIL INVESTIGATION SHALL PROVIDE A FIELD REPORT (IN WRITING) WHICH SHALL 7, EARTHWORK QUANTITIES ARE APPROXIMATE ONLY AND ARE STATE THE BUILDING NOT INTENDED FOR CONTRACT PURPOSES. SITE MAP A. THE BUILDING E S WAS PREPARED PE COMPACTED IN $ THE CONTRACTOR SHALL MAKE HIS REQUEST FOR STAKES ACCORDANCE W11H THE SOIL REPORT AND SPECIFICATIONS. B. THE FOUNDATION AND /CR PIER EXCAVATION, DEPTH AND BACKFILL TO THE OWNER'S ENGINEER NOT LESS THAN 72 HOURS ^ -�0 MATERIALS, AND DRAINAGE (IF APPLICABLE) SUBSTANTIALLY CONFORM TO BEFORE THE TIME HE WISHES TO COMMENCE GRADING BIRTH WORK SUMMARY THE SOIL REPORT AND APPROVED PLANS. OPERATIONS. 116. PRIOR TO FINAL INSPECTION FOR ANY BUILDING OR STRUCTURE, THE 9, ANY TREES WHICH ARE TO RE PRESERVED AND WHICH BTq; CUT FILL OEOIECHNICAL ENGINEER OR CIVIL ENGINEER WHO PREPARED THE SOIL FALL WITHIN THE GRADING LIMITS FOR THE PROPOSED INVESTIGATION SHALL ISSUE A FINAL REPORT STATING THE CphApLETEJ) PAD, RESIDENCE SHALL BE FIELD CHECKED FOR LOCATION ANO FOUNDATION, FINISH GRADING, AND ASSOCIATED SITE WORK SUBSTANTIALLY GRADE BY THE ENGINEER OR THE CONTRACTOR PRIOR TO CONFORM TO THE APPROVED PLANS, SPEUMCATTONS, AND INVESTIGATION. COMMENCEMENT OF GRADING OPERATIONS. NOTIFY THE 1 • -13 +I0 73 p ENGINEER OR ARCHITECT IMMEDIATELY IF ADJUSTMENTS ARE 13-80- 16+50 0 0 REQUIRED. 1fi +50 -16 +50 s6 66 TSICIVIL ENGINEERING GENERAL NOTES: 70' ALL TREES To BE REMOVED SHALL B vER,FIED BY THE TOTAL 629 66 AROBI$T. �- T. TS /CIVIL ENGINEERING, INC. ASSUMES NO RESPONSIBILITY BEYOND THE 11. THE CONTRACTOR SHALL SET HIS OWN STRING OR WIRE PLACE; Aca> =s S&r CKRequrRNfiNrs ='G FLUOR ADEQUACY OF THEIR DESIGN CONTAINED HEREIN. TIiROUGH AT LEAST THREE GRADE STAKES TO VERIFY THE sLOFE ARE1 2 CONTRACTOR AGREES THAT HE GRADE IF THE STAKES DO NOT :PRODUCE A UNIFORM rr /SHE SHALL ASSUME SOLE AND COMPLETE GRADE, NOTIFY THE ENGINEER IMMEDIATELY Ako HAVE THE RESPONSIBiUTY FOR JOB SITE CON01'RONS DURING THE COURSE OF GRADE CHECKED PRIOR TO TRENCHING OR PLACING OF a CONSTRUCHON OF THE PROJECT, INCLUDING SAFETY OF A' PERSONS AND C0 >.�RE7E, RC.jUin" ia[li" s.':.I� .•, ^:^ C ^�' J.'USLY AND NOT 1�. CCNT:HAC102 SHALT ALL {: RG I11[t7Cn Tn 1Jl1p4181 wngl[I�I(. I.IN IOC• e7,1r1 —IT ",11F' -" -S `^'F ]�'2v: _ - -r V; •ePOFAI rT�'c s rl,Fl Tn' nCTCO�rluf n.c O.MERS: .may, '1[ "YT'; � -'�J '.34 •_Nl.ii,_ 1: SLVVL AND ::1: ? -. , °� '� ML �IT HARMLESS FROM ANY AND ALL UABUTY, REAL OR ALLEGED, IN DISCREPANCY '.�ir'� .` CONNECTIONN WITH THE PERFORMANCE OF WORK ON THIS PROJECT, EXCEPT is DETECTED. 0640 ANm101', COUHT FOR LIABILITY ARISING FROM THE 501-E NEGLIGENCE OF THE OWNER OR THE CONFORM WHEREVER FXIS -nNG CURB AND CUTT,RT SH NTENDED T SARATOGGA CA,395070 ENGINEER. CONTRACTOR'S RESPONSIBILITY TO CHECK THE RELATIONSHIP 3. TS /CIVIL ENGINEERING, INC. WILL NOT RE RESPONSIBLE FOR DRAINAGE OF HIS FORMS OR SUBGRADE TO THE EXISTING PAVEMENT TO LOT B: TOM LIM & ELLEN CHAN UNLESS THEY ARE AUTHORIZED TO MAKE AN -AS- BUILT' SURVEY AFTER VERIFY THAT HE HAS THE CORRECT GRADE DIFFERENTIAL. 10654 FLORA VISTA AVENUE {••4'no.1a � THE LANDSCAPE IS COMPLETE AND BEFORE OCCUPANCY, 14. PADS INDICATED AS LEVEL SHALL NOT VARY FROM TRUE CUPERTINO. CA 55014 4. TS CIVIL ENGINEERING, INC. ONLY ACKNOWLEDGES ORIGINAL SIGNED AND HORIZONTAL PLANE BY MORE THAN PtUS OR MINUS 0.1 FOOT (408)996 -0846 STAM Ep PLANS AND ORAWINGS, NO RESPONSIBILITY OR LIABILITY IS LOWER NOR 0.1 FOOT HIGHER THAN THE ELEVATION EXPRESSED OR IMPLIED FOR ELECTRONIC DATA ANC /OR REPRODUCED PLANS INDICATED ON THIS PLAN UNLESS OTHERWSE INDICATED LOT C: DAN & NANCY CHEADLE AND DRAWINGS. HEREON OR PERMITTED BY THE OWNER, 12489 GREEN MEADOW LANE 5. IN THE CASE OF CONFLICTS, THE REQUIREMENTS OF THE EARTHWORK 15. THE CONTRACTOR SHALL CALL TS CIVIL ENGINEERING, INC. SARATOGA. CA 95070 SPECIFICATIONS PREPARED FOR THIS PROJECT BY THE SOILS ENGINEER 72 HOURS PRIOR TO PLACEMENT OF CONCRETE FOR CURBS (408)255 -6462 SHALL DOYEN OVER THE REQUIREMENTS OF THIS PLAN AND THESE NOTES, CR OTHER STRUTURES AND REQUEST A GRADE CHECK. TS CONC 6. THE EARTHWORK QUANTITIES SHOWN HAVE BEEN DILIGENTLY ESTIMATED CIVL ENGINEERING. INC. WILL NOT BE RESPONSIBLE FOR THE LOT D: FONG LIM BY THE OWNER'S ENGINEER BASED UPON AVAILABLE INFORMATION IN ORDER GRADE LOCATICN OF ANY CONCRETE STRUCTURES UNLESS 492 °EOOARA DRIVE TO ASSIST THE CONTRACTOR IN ESTIMATING COST AND OBTAINING A THE ABOVE CHECK HAS BEEN MADE AND THE GRADES AND L02 ALTOS, CA BALANCE OF, MATERIAL ON THE SITE HOWEVER, 17 SHALL BE THE LOCATIONS FOUND TO BE ACCEPTABLE. (650)575 -1360 CONTRACTORS RESPONSIBILITY TO VERIFY EARTHWORK QUANTITIES AND TO 16. ALL GUTTERS SHALL BE WATER TESTED TO DETECT "BIRD AFFECT A BALANCE. THIS SHALL INCLUDE REQUIRED IMPORT OR EXPORT BATHS'. BIRD BATHS SHALL SE REMOVED WMECIATELY WITH NO ADDITIONAL COMPENSATION FROM THE OWNER. BEFORE THE CONCRETE CURES. PREPARED N R SI N 5 5 • n 4 xa arrx ts+. u -ao-47 3 _Z_clvL 4 cx al.+ J A 1 RCE 35527 EXP. 9 -30 -07 eY REVSICNS DATE PH: 408.452.8300 TOLL FREE: 8BB, ,� .. I, , - 3s6- 14 -05. ALLA GR SITE MAP .. ABBREVIATIONS 4� 1(1ig r i AS AGGREGATE BASE ! Fl- CE} ExIS71NC y- ) ��R..xYYpppQQQ ! FL FLOW UHE um mn FJS[aILnT P PAVEMENT (e ]RYH OR 96+) / FG A iN S DE �„ l-' !'J 366 -14 -960 FS HNISN SURFACE s r w ,� weR r , ' " Y,�,`. -- L LENGTH / _ f�,. .0 e / S SLOPE `_r` O a G GRCUNC MP OF WRB .. AAA PRE�+pCS �,,• —• d }f ti 5 1 .. 1 LA r u,GNA1 SID 5 PROPOSED ' f' x-E� i f r F f E 3S ? I E STANUA " ..� I f��"'v - NP NIBS POINT ff Ih F 1 PVC POLWNYL CHLORIDE YGP 'ATRn CLAY PIP E ftcP nFuRCED CONCRETE PIPE CAV racN PsE n 0i INV INVERT a 9w a OF WALK DI DRAIN INLET FP EDGE OF PAVEMEN7 HIGH MN SITY Pd.YE7H1lENE MNx MAXIMUM e W,� 1 PD PULL Om STA TOP OP OF T CY'► i Y rl . w OF K WALL OT A r .,Y,+- ; 11. is w -` o E ' � c DVAVERRTICAL CURVE VM71CAL, CURVE PVI POINT OF vERTICAL INTERSEC oN IE LA ' Ord rr1 n a, # M MIO➢IEORDINATE MP MIGDLE OROi-TE PANT OF Y TX-AL INTEREE.Mt: •I4` PRVC POINT OF REVERSE vERNCAL CURVE 7 AGR - �L //.. /f.w � •, BYC BEAN VERTICAL CLRAE WATER S WWI` vhlnED MAE P ABRIC I- eoG- zTT -zew �mec +-e0o-7I1 -190a ` LLL��...,,, L� a rm AST LEGEND II r� /k E%. CONTOUR MAJOR ` YYrI,V f ;.Y.: .. EY. CONTOUR MINOR - -- -- - - EX. BUILDING, DRIVEWAY E. ROAD Ex. STORM D INNLJ UNE .. ._. _.... _.. Ex, STORM DRAIN LINE OVERHEAD WIRE Lot 0 `� ) EX WRIER LINE V�y EX GAS LINE EX. TOP OF HANK �^ EX SWALE FLOWUNE Ex mRN & =TIER Tr'4� R V I T::..l.:.:.:'r.:.:.1.2:.r _ i.:, :,F. °...',.., .. E%. RETAINING WALL z7- A�IIALr r WARS R x AGCREGAmE . Ex, FENCE E % PRIVATE ACCESS ROAD —" - E ECTRIC NINE ss PROPOSED SANITARY SEVER 9TA: 16 +87.24 TO END m PROPOS D GAS RN DRAIN w'.. PROPOSED WATER PROPOSED SUILDNP PROPOSED BURRING M?p IS.6rdC � I`WS. -s PRt,PO5E1, llr.Nl'ulitil lµF:; io' PPoVAit NGAG PROPOSED TB VECETAIION SWALE/F'LOW LINE Mr - - - -- EUILOING SEACK LINES PROPERTY LINE .. '"A- `r✓ IG d _ -, SYREL CENTER LINE noNrc -stw[ iIKER + att aePe .-_ - -.. ... ADJACENT R GH1 F AY 5 MAK REr-" — PROPOSED RIOHT OF WAY .y.r�Y Y451L wm oPR3EC Cl rPilUNG � REjuNW01YML �, ': , ,i i,,,R PROPpSEp 001YUGNT LINE R[n ia+imAnav Ax s �� E;RSIINC fA5F7eENT (STA +&s- m �, = IIfmY __ wyL taraoaw, GRANx WALL FWNGAROR " " SHEET INDEX ' ` wA u zs• A .- COVER SHEET C -7 AGGRLGA1t BASE CONSTRUCTION GRADING 8 DRAINAGEPfAN C -2 PRIVATE ACCESS ROAD CONSTRUCTION C ACCESS UROAD CROSS -S CT C-3 STA: 9 +95 -68 TO 16 +87.24 PRIVATE CONTROL ROADCRO55- SECTIONS C-4 EROSION CONTROL PLAN C -5 N TS TREE PROTECTIVE MEASURES T -1 & T -2 NOTE: i.) sECT10hl FROM 1G+OO TO 12 +70 TO BE 6 " CONCRETE WITH WWF /8" CLASS 11 AB WITH SCORED SURFACE SCOPE OF WORK: 2.) SEE PLAN VIEW FOR LIMITS OF RETAINING WA4.L 1. CONTMucT A PRIvATE ACCESS ROAD FOR LOTS A -D. ENGINEERING, INC. COVER SHEET DATE: 101131oo SHEET NO HNOLOGY DRIVE SCALE: 11h6w E, CA 95410 LANDS OF HALL ORAWN EY: SK C =1 WFIING 20865 WARDELL ROAD SURVEYED BY: NB OF 5 SHEETS SARATDGA, � a+ PROJ ENGR: ma JOB N0. FAX: dO8,452.9309 A CHECK BY! TJ8 0 0 0 0 F 1� T of JV Y I' i 1' 1' 1 1 1 1 r r r 1 i i I Stormwater Control Plan II. MEASURES TO LIMIT IMPERVIOUSNESS II.A. Measures to Make Development More Compact The following site layout characteristics help reduce watershed imperviousness: • Limitation to 15,000 SF impervious coverage per lot. • The site design includes sizeable landscaped and urban open space areas throughout the site which will be maintained after residence development. Hillside conditions require a balance between collecting and expediting run -off versus on -site detention. Surface streets should be quickly drained to maintain vehicle traction. Depth of impoundment is problematic where slopes are steep and potentially de- stabilized by saturation. However, the landscape swale system is ideal to provide the necessary infiltration on this site while limiting potential negative impacts on slope stability and aesthetics. II.B. Location of Refuse Areas Typically refuse areas on projects are located outdoors, which contributes greatly to the potential for 1 polluted stormwater runoff. However, the site incorporates a design where individual trash pick up can be centralized and runoff controlled by curbs. I 1 III. SELECTION AND PRELIMINARY DESIGN OF STORMWATER TREATMENT BMPS The site has been divided into four distinct areas as shown on the BMP Exhibit. 1 Runoff from each of these areas is managed and routed differently according to site specifics and drainage characteristics. Given the unique topography of the site, these individual areas will handle rr stormwater runoff differently. The stormwater treatment facilities will have suitable access for inspection and maintenance. The I Stormwater Control flan Exhibit shows the treatment facilities to be used on the site, as well as the potential location of future residences. M III.A. General Characteristics of the Treatment Facilities The facilities will be designed and constructed in accordance with the illustrations and specifications in the Stormwater G3 Guidebook, including a minimum 12" depth of sandy loam ( minimum infiltration rate specified to be 5" per hour). All treatment facilities will be underdrained, and the undetdrains will be connected to underground storm drains to convey treated runoff, as well as overflow, to the 24" storm drain at the north property line. All drainage into and away from the facilities is by gravity, eliminating the need to collect and pump stormwater and avoiding the need for vaults. 3 N 1 1 II 1 r 1 1 IV. SOURCE CONTROL MEASURES Stormwater Control Plan The following activities planned for this development have potential to allow pollutants to enter runoff: • x Landscape maintenance • x Maintenance and washing of residents' vehicles All areas where these activities occur will drain to Stormwater treatment facilities. To further reduce the potential for pollutants to enter runoff, permanent and operational BMPs will be implemented as described in Table 2. TABLE 2 - Sources and Source Control BMPs ��Ror te "n #a5ot�rce 4 Mp r K..t... B, noal.B MPs. On -site drain inlets. .. he drainage design reduces on -site inlets, xcept for area drains in the landscaped inlet markings will be inspected annually and rea and overflows in the stormwater replaced or renewed as needed. reatment BMPS. This substantially reduces Residential lessees will receive stormwater he potential for dumping. Inlets that could pollution prevention information to be be accessed from sidewalks and driveways provided by the City, ill be marked with "No dumping -- Drains to Stormwater Planter BMPs and related Creek" or similar message. structures and features will be inspected and maintained as specified in the Stormwater Control Operation and Maintenance Plan (to be developed and submitted for approval). Interior floor drains and ll such drains will be plumbed to the Drains will be periodically inspected to avoid elevator shaft sump anitary sewer. blockages and overflow. pumps. Basements ny floor drains in the covered parking area Drains will be periodically inspected to avoid re to be plumbed to the sanitary sewer. blockages and overflow. Need for future indoor Standard building design minimizes wrners will receive integrated pest and structural pest potential need for future pest control, management information to be provided by the control. ity Landscapeloutdoor Any native trees, shrubs, and ground Owners will receive integrated pesticide use cover on the site will be preserved to the pest management information to be provided maximum extent possible, by the City. Landscaping will be designed to minimize All site landscaping is to be maintained by a required irrigation and runoff, to promote professional landscaping contractor. surface infiltration, and to minimize the Contract to state that landscaping is to be use of fertilizers and pesticides that can maintained using Integrated Pest contribute to stormwater pollution. Management (IPM) principles, with minima! Where possible, pest - resistant plants will or no use of pesticides. be selected, especially for locations adjacent to hardscape. Plants will be selected appropriate to site soils, slopes, climate, sun, wind, rain, land use, air movement, ecological consistency, use of recycled water (where applicable), and plant interactions. 9 10 3tarmwater Control Plan M 1)I�r b'tY+^ }' tM -yi } � �}.aten,tl I Source r,. ��wlA,'�pr� - � �� i.%'��f ��♦ Y� � vsak iuJ� J¢F t}IT Ail NN; }� Ik } 51 ill'•' _'.. 1 - u Nd W 7L1 �JV i) E gMPs 1Opsecatlortal ;,,TI I!} BMPs Refuse areas Refuse areas with floors sloped to prevent wners will inspect and clean up daily. Spills ramage to exterior. Any floor drains must ill be cleaned up using dry methods. onnect to sani tary sewer. ehicle and equipment feanin g !i paved parking areas drain to sewer Residential zoning will prohibits maintenance, rather than directly to storm drains. Hose repair, or cleaning of other equipment on site. bibs will have automatic shutoff or will require keys to operate. Fire sprinklers prinkler test and system drain water shall of discharge into the storm drain, Provisions to direct water to t*sanitary ewer or landscape or other approved means shall be provided. Sprinkler system esign shall include the proposed method or drainage of sprinkler system discharge. Miscellaneous drain or Condensate drain lines will discharge to Drainage sumps shall be cleaned of ash water the sanitary system or to landscaped ccumulated litter, debris, and sediment, and areas. aterial properly disposed. Rooftop mounted equipment will be roofed or covered to prevent pollutants from entering runoff. Roofing, gutters, and trim shall not be copper or other unprotected metal that could leach into runoff. 10 V. PERMITTING AND CODE COMPLIANCE ISSUES Stormwater Control Plan There are no known conflicts between the proposed Stormwater control plan and City of Saratoga ordinances or policies, Any conflicts that are found will be resolved through the design review process or during subsequent permitting, VI. BMP OPERATION AND MAINTENANCE VI.A. Means to Finance and Implement BMP Maintenance Proper operation and maintenance of Stormwater Management Facilities will be the responsibility of the property owner in perpetuity. The property owner may be subject to an annual fee (set by the City's standard fee schedule) to offset the cost of inspecting the site or verifying that Stormwater management facilities are being maintained. The applicant will prepare and submit, for the City's review, an acceptable Stormwatet Control Operation and Maintenance Plan prior to completion of construction and will execute a Stormwater Management Facilities Operation and Maintenance Agreement before sale, transfer, or permanent occupancy of the site. The applicant accepts responsibility for maintenance of stormwater management facilities until such responsibility is transferred to another entity. VI.B. Summary of Maintenance Requirements Stormwater swales remove pollutants primarily by filtering runoff slowly through an active layer of soil. Routine maintenance is needed to insure that flow is unobstructed, that erosion is prevented, and that soils are held together by plant roots and are biologically active. Typical routine maintenance consists of the following: • Inspect inlets for channels, exposure of soils, or other evidence of erosion. Clear any obstructions and remove any accumulation of sediment. Examine rock or other material used as a splash pad and replenish if necessary. • Inspect outlets for erosion or plugging. • Observe soil in the swale or planter for uniform percolation thtoughout. If portions of the swale or filter do not drain within 48 Hours after the end of a storm, the soil should be tilled and replanted. Remove any debris of accumulations of sediment. • Examine the vegetation to insure that it is healthy and dense enough to provide filtering and to protect soils from erosion. Replenish mulch as necessary, remove fallen leaves and debris, prune large shrubs or trees, and mow turf areas. Confirm that irrigation is adequate and not excessive. Replace dead plants and remove invasive vegetation. • Abate any potential vectors by filling holes in the ground in and around the swale and by insuring that there are no areas where water stands longer than 48 hours following a storm. If mosquito larvae are present and persistent, contact the Santa Clara County Vector Control District for information and advice. Mosquito larvicides should be applied only when absolutely necessary and then only by a licensed individual or contractor. 11 i 1 1 Stormwater Contra) Plan TABLE 3 - Construction Plan C.3 Checklist qqt r�Bi� @�Q.nC. @�k rn 7 } 4 v wiMt�N r7 3a� hN'e�Y4i}!11 o f r. �nZ,40 S bee t' s y.�d: �F �it?� y hiieS"�' s r✓c .a� ° s H�rilbe� Table 1, Exhibit and , 11 lots routed to appropriately sized landscape swale BMPs at the Section 11,6,1 perimeter of the buildings, Table 2 Inlets that could be accessed from sidewalks or driveways (if any) to be "no marked with dumping" message. Table 2 11 interior floor drains, including in residential indoor parking area, are plumbed to sanitary sewer, Table 2 Plant selection to minimize irrigation, minimize use of fertilizers and Pesticides, and for pest resistance. Table 2 ppropriate plantings are specified for swale and planters. Table 2 Hose bibs on residential buildings to have automatic shutoff or require keys to operate. Table 2 ondensate drain lines discharge to landscaped areas or sanitary ewer. Table 2 Rooftop mounted equipment to be covered to prevent pollutants from ntering runoff. Table 2 prinkler test and system drain water shall not discharge into the storm rain. Provisions to direct water to the sanitary sewer or landscape or then approved means shall be provided. Sprinkler system design shall include the proposed method for drainage of sprnkier system ischarge. Table 2 No roofing, gutters, and trim made of copper or unprotected metals that may leach into runoff. 12 Stormwater Control Plan VII. CERTIFICATION The selection, sizing, and preliminary design of treatment BM-Ps and other control measures in this plan meet the requirements of Regional Water Quality Control Board Order 01 -119, as amended. This original Stormwater Control Plan was prepared *n October 2006, by Project Engineer "for TS /Civil Engineering, Inc. The work for this project was performed as directed and authorized by Wardell Road Lot Owners. TS /CML ENGINEERING, INC. Terence J. Szewczyk Principal Engineer Z YJW IVA r �QROFESSION �yQ'E'. SZF fi W , C 35527 m EXP 9130107 I " CIM W October 25 2006 DATE 13 stormwater Control Plan Note to BMP sizing: The sizing factor of 0.034 is specified in Chapter Five of the City of Milpitas Stormwater C.3 Guidebook. The factor is derived by matching the design flow rate to the infiltration rate through the sandy loam in the swale, in- ground planter, or flow - through planter. The design flow rate is 0.17 inches per hour — the 85`' percentile hourly rainfall intensity times two, as specified in Provision C.3.d of the City's stormwater NPDES permit — times the tributary area. The flow through the treatment facility is 5 inches per hour — the specified minimum infiltration rate of the imported sandy loam — times the surface area of the planter. When Q (inflow) = Q (infiltration) at the design flow, C *i *A (impervious) = infiltration rate * surface area of BMP. Using the conservative assumption that the runoff factor C = 100 %, the ratio of BMP surface area to impervious area = 0.17/5 = 0.034 (dimensionless). BMP — Landscape Swale Summary 4 Lots x 230 LF / EA = 920 LF Private Road 1 x 170 LF = 170 LF Project Total 1,090 LF Currently Provided 170 (Lot A) 27 (Lots C & D) Future Landscape Swales by Lots 650 LF / 4Lots = 163' x 4' Wide by Each Lot. 14