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Grading and Drainage �! Santa Clara Valley Urban Runoff Pollution Prevention Program PROVISION C.3 DATA FORM Which Projects Must Comply with Stormwater Requirements? All projects that create and/or replace 10,000 sq.ft.or more of impervious surface on the project site must fill out this worksheet and submit it with the development project application. All restaurants,.auto service facilities,retail gasoline outlets,and uncovered parking lot projects (stand-alone or part of another development project,including the top uncovered portion of parking structures)that create and/or replace 5,000 sq.ft. or more of impervious surface on the project site must also fill out this worksheet. Interior remodeling projects,routine maintenance or repair projects such as re-roofing and re-paving, and single family homes that are not part of a larger plan of development are NOT required to complete this worksheet. What is an Impervious Surface? An impervious surface is a surface covering or pavement that prevents the land's natural ability to absorb and. infiltrate rainfall/stormwater. Impervious surfaces include,but are not limited to rooftops, walkways,paved patios, driveways,parking lots, storage areas,impervious concrete and asphalt, and any other continuous watertight pavement or covering. Pervious pavement,underlain with pervious soil or pervious storage material(e.g., drain rock),that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal Regional Stormwater Permit(MRP),is not considered an impervious surface. For More Information For more information regarding selection of Best Management Practices for stormwater pollution prevention or stormwater treatment contact: 1. Project Information Project Name: 2295 & 2305 S. Winchester Blvd. APN# 305-34-004/005 Project Address: 2295 & 2305 S. Winchester Blvd. Cross Streets: El Caminito Avenue Applicant/Developer Name Jeff Warmoth/SREA, Inc. Project Phase(s): 1. of Engineer: Mark Knudsen / Kier& Wright Civil Engineers Project Type (Check all that apply): ❑ New Development- ❑ Redevelopment ❑ Residential ❑ Commercial ❑ Industrial N Mixed Use ❑ Public ❑ Institutional ❑ Restaurant ❑ Uncovered Parking ❑ Retail Gas Outlet ❑ Auto Service (SIC code) 0 Other (5013-5014,5541,7532-7534,7536-7539) Project Description: Construction mixed-use retail with residential above. I Project Watershed/Receiving Water(creek, river or bay):Los Gatos Creek SCVURPPP C.3.Data Form Page 1 of 4 November 2011 t .2.Project Size a.Total Site Area: b.Total Site Area Disturbed: 0.566 acre 0.574 acre (including clearing,gar ing,or excavating) Proposed Area(fe) Total Post-Project Existing Area(ftz) Replaced New Area(ft-) Impervious Area Roof 5,505 5,505 8,965 14,470 Parking 3,191 3,191 3,810 7,001 Sidewalks and Streets 2,799 581 0 581 c.Total Impervious Area 11,495 9,277 12,775 22,052 d.Total new and replaced impervious area 22,052 Pervious Area Landscaping 13,500 0 2,612 Pervious Paving 0 0 0 0 Other(e.g.Green Roof) 0 0 0 0 e.Total Pervious Area 13,500 0 23612 f.Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious Area Existing Total Impervious Area) x 100% = 81% % 3. State Construction General Permit Applicability: a. Is#2.b. equal to 1 acre or more? ❑ Yes, applicant must obtain coverage under the State Construction General Permit (i.e., file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see www.swrcb.ca.gov/water issues/progtams/stormwater/construction.shtml for details). ® No, applicant does not need coverage under the State Construction General Permit. 4. MRP Provision C.3 Applicability: a. Is#2.d. equal to 10,000 sq. ft. or more, or 5,000 sq. ft. or more for restaurants, auto service facilities, retail gas outlets, and uncovered parking? ('-Note that for public projects, the 5,000 sq.ft. threshold does not take effect until 1211112.) ® Yes, C.3. source control, site design and treatment requirements apply ❑ No, C.3. source control and site design requirements may apply—check with local agency b. Is#2.f. equal to 50% or more? ® Yes, C.3. requirements (site design and source control, as appropriate, and stormwater treatment) apply to entire site ❑ No, C.3. requirements only apply to impervious area created and/or replaced 5. Hydromodification Management(HNI) Applicability: a. Does project create and/or replace one acre or more of impervious surface AND is the total post-project impervious area greater than the pre-project (existing) impervious area? ❑ Yes (continue) ® No—exempt from HM, go to page 3 b. Is the project located in an area of HM applicability(green area) on the HM Applicability Map? ( www.scvurp1212-w2k.com/hmp maps.htm) ❑ Yes, project must implement HM requirements ® No, project is exempt from HM requirements SCVURPPP C.3.Data Form Page 2 of 4 November 2011 4 6. Selection of Specific Stormwater Control Measures: Site Design Measures Source Control Measures Treatment Systems ❑ Minimize land disturbed ❑ Alternative building ❑ None (all impervious surface materials drains to self-retaining areas) ❑ Minimize impervious surfaces ❑ Wash area/racks, drain to LID Treatment ❑ Minimum-impact street sanitary sewer ❑ Rainwater harvest and or parking lot design ❑ Covered dumpster area, use (e.g.,cistern or rain barrel drain to sanitary sewer sized for C.3.d treatment) ❑ Cluster structures/ - pavement ❑ Sanitary sewer ❑ Infiltration basin ❑ Disconnected downspouts connection or accessible ❑ Infiltration trench cleanout for swimming ❑ Pervious pavement pool/spa/fountain2 ❑ Exfiltration trench ❑ Green roof ❑ Beneficial landscaping ❑ Underground detention (minimize irrigation,runoff, and infiltration system ❑ Microdetention in pesticides and fertilizers; (e.g.pervious.pavement drain landscape promotes treatment) rock,large diameter conduit) ® Other self-treating area ❑ Outdoor material storage Biotreatment 3 ❑ Self-retaining area protection ® Bioretention area ❑ Rainwater harvesting and ❑ Covers, drains for loading ❑ Flow-through planter use maintenance bays (e.g.,rain barrel,cistern docks, , g ❑ Tree box with connected to roof drains)1 fueling areas , bioretention soils ❑ Preserved open space: ® Maintenance (pavement ❑ Other ac. or sq. ft sweeping,catch basin .(circle one) cleaning,good housekeeping) ❑ Protected riparian and ❑ Storm drain labeling Other Treatment Methods wetland areas/buffers ❑ Proprietary tree box filter' from top of bank: ❑ Other ft) ❑ Media filter.(sand,compost, or proprietary media)4 ❑ Other ❑ Vegetated filter strips ❑ Dry detention basins ❑ Other Flow Duration Controls for Hydromodification Management(HM) ❑ Detention basin ❑ Underground ❑ Bioretention with outlet ❑ Other tank or vault control 1 Optional site design measure;does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. 3 Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater harvest and use are infeasible. 4 These treatment measures are only allowed if the project qualifies as a"Special Project". 5 These treatment measures are only allowed as part of a multi-step treatment process. SCVURPPP C.3.Data Form Page 3 of 4 November 2011 7. Treatment System Sizing for Projects with Treatment Requirements Indicate the hydraulic sizing criteria used and provide the calculated design flow'or volume: Treatment System Component Hydraulic Sizing Design Flow or Criteria Used Volume (cfs or cu.ft.) Biotreatment 2c 0.082 cfs 3Key: la: Volume—WEF Method lb: Volume—CASQA BMP Handbook Method 2a: Flow—Factored Flood Flow Method 2b: Flow—CASQA BMP Handbook Method 2c: Flow—Uniform Intensity Method 3: Combination Flow and Volume Design Basis 8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third- party professional that is not a member of the project team or agency staff? ❑ Yes 0 No Name of Reviewer 9. Operation &Maintenance Information A. Property Owner's Name Jeff Warmoth B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M: a. Name: Jeff Warmoth b. Address: P.O. Box 1001 Los Altos, CA 94023 c. Phone/E-mail: jeffwarmoth@gmail.com This section to be completed by Municipal staff. O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply: ❑ O&M Agreement ❑ Other mechanism that assigns responsibility(describe below): Reviewed: Community Development Department Public Works Department Planning Division: Engineering: Building Division: Other(Specify): Return form to: Data entry performed by: SCVURPPP C.3.Data Form Page 4 of 4 November 2011 Santa Clara Valley Urban Runoff Pollution Prevention Program Infiltration/Harvesting and Use Feasibility Screening Worksheet Apply these screening criteria for C.3 Regulated Projects*required to implement Provision 0.3 stormwater treatment requirements. See the Glossary(Attachment])for definitions of terns marked with an asterisk(*). Contact municipal staff to determine whether the project meets Special Project*criteria. If the project meets Special Project criteria, it may receive LID treatment reduction credits. 1. Applicant Info Site Address: 2295 & 2305 S. Winchester Blvd. ., CA APN: 305-34-004/005 Applicant Name: Phone No.: Mailing Address: 2. Feasibility Screening for Infiltration Do site soils either(a)have a saturated hydraulic conductivity*(Ksat)that will NOT allow infiltration of 86% of the annual runoff(that is,the Ksat is LESS than 1.6 inches/hour),or,if the Ksat rate is not available,(b)consist of Type C or D soils?' ❑ Yes (continue) ❑ No—complete the Infiltration Feasibility Worksheet.If infiltration of the C.3.d amount of runoff is found-to be feasible,there is no need to complete the rest of this screening worksheet. 3. Recycled Water Use Check the box if the project is installing and using a recycled water plumbing system for non-potable water use. ❑ The project is installing a recycled water plumbing system,and installation of a second non-potable water system for harvested rainwater is impractical,and considered infeasible due to cost considerations. Skip to Section 6. 4. Calculate the Potential Rainwater Capture Area*for Screening of Harvesting and Use Complete this section for the entire project area. If rainwater harvesting and use is infeasible for the entire site, and the project includes one or more buildings that each have an individual roof area of 10,000 sq.ft. or more, then complete Sections 4 and 5 of this form for each of these buildings. 4.1 Table 1 for(check one): ❑The whole project ❑ Area of 1 building roof(10,000 sq.ft.min.) Table 1: Calculation of the Potential Rainwater Capture Area* The Potential Rainwater Capture Area may consist of either the entire project area or one building with a roof area of 10,000 sq.ft.or more. 1 2 1 3 4 Pre-Project Proposed Impervious Surface'(IS),in Post-project Impervious surface2 sq.ft. landscaping (sq.ft.),if applicable 3 a (sq.ft.),if Replaced IS Created IS applicable a.Enter the totals for the area to be evaluated: 11,495 9,277 12,775 2,612 b.Sum of replaced and created impervious surface: N/A 22,052 N/A c.Area of existing impervious surface that will NOT be replaced by the project. 0 N/A NIA 'Base this response on the site-specific soil report,if available.If this is not available,consult soil hydraulic conductivity maps in Attachment 3. '-,Enter the total of all impervious surfaces,including the building footprint,driveway(s),patio(s),impervious deck(s),unroofed porch(es),uncovered parking lot(including top deck of parking structure),impervious trails,miscellaneous paving or structures,and off-lot impervious surface(new,contiguous impervious surface created from road projects,including sidewalks and/or bike lanes built as part of new street).Impervious surfaces do NOT include vegetated roofs or pervious pavement that stores and infiltrates rainfall at a rate equal to immediately surrounding,unpaved landscaped areas,or that stores and infiltrates the C.3.d amount of runoff*. 3"Replaced"means that the project will install impervious surface where existing impervious surface is removed. a"Created"means the project will install new impervious surface where there is currently no impervious surface. *For definitions,see Glossary(Attachment 1). Page 1 of 3 FINAL November 2011 Infiltration/Hari) 'and Use Feasibility Screening Worksheet 4.2 Answer this question ONLY if you are completing this section for the entire project area. If existing impervious surface will be replaced by the project, does the area to be replaced equal 50% or more of the existing area of impervious surface? (Refer to Table 1, Row "a". Is the area in Column 2 >50%of Column I?) ❑ . Yes, C.3. stormwater treatment requirements apply to areas of impervious surface that will remain in place as well as the area created and/or replaced.This is known as the 50%rule. ❑ -No,C.3.requirements apply only to the impervious area created and/or replaced. 4.3 Enter the square footage of the Potential Rainwater Capture Area*.If you are evaluating only the roof area of a building, or you answered"no" to Question 4.2, this amount is from Row "b"in Table 1. If you answered"yes" to Question 4.2,this amount is the sum of Rows"b"and"c"in Table l.: 22,052 square feet. 4.4 Convert the measurement of the Potential Rainwater Capture Area* from square feet to acres (divide the amount in Item 4.3 by 43,560): 0.51 acres. 5. Feasibility Screening for Rainwater Harvesting and Use 5.1 Use of harvested rainwater for landscape irrigation: Is the onsite landscaping LESS than 2_5 times the size of.the Potential Rainwater Capture Area* (Item 4.3)? (Note that the landscape area(s)would have to be contiguous and within the same Drainage Management Area to use harvested rainwater for irrigation via gravity flow.) ❑ Yes(continue) ❑ No — Direct runoff from impervious areas to self-retaining areas*OR refer to Table 11 and the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for irrigation. 5.2 Use of harvested rainwater for toilet flushing or non-potable industrial use: a. Residential Projects: Proposed number of dwelling units. 16 du Calculate the dwelling units per impervious acre by dividing the number of dwelling units by the acres of the Potential Rainwater Capture Area*in Item 4.4. Enter the result here: 32 Is the number of dwelling units per impervious acre LESS than 100(assuming 2.7 occupants/unit)? ❑ Yes (continue) ❑ No— complete the Harvest/Use Feasibility Worksheet. b. Commercial/Industrial Projects: Proposed interior floor area- 3,300 (sq.ft.) Calculate the proposed interior floor area(sq.ft:)per acre of impervious surface by dividing the interior floor area (sq.ft.)by the acres of the Potential Rainwater Capture Area*in Item 4.4. Enter the result here: 6,471 Is the square footage of the interior floor space per impervious acre LESS than 70,000 sq. ft.? ❑ Yes(continue) ❑ No—complete the Harvest/Use Feasibility Worksheet c. School Projects:Proposed interior floor area: (sq.ft.) Calculate the proposed interior floor area per acre of impervious surface by dividing the interior floor area (sq.ft.)by the acres of the Potential Rainwater Capture Area*in Item 4.4.Enter the result here: Is the square footage of the interior floor space per impervious acre LESS than 21,000 sq. ft.? ❑ Yes(continue) ❑ No—complete the Harvest/Use Feasibility Worksheet For definitions,see Glossary(Attachment 1). Page 2 of 3 FINAL November 2011 1 biftltratio»/Harw and Use Feasibility Screening Worksheet d. Mixed Commercial and Residential Use Projects • Evaluate the residential toilet flushing demand based on the dwelling units per impervious acre for the residential portion of the project,following the instructions in Item 5.2.a,except you will use a prorated acreage of impervious surface,based on the percentage of the project dedicated to residential use. • Evaluate the commercial toilet flushing demand per impervious acre for the commercial portion of the project,following the instructions in Item 5.2.a,except you will use a prorated acreage of impervious surface, based on the percentage of the project dedicated to commercial use. e. Industrial Projects: Estimated non-potable water demand(gal/day): Is the non-potable demand LESS than 2,400 gal/day per acre of the Potential Rainwater Capture Area? ❑ Yes (continue) ❑ No— refer to the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for industrial use: 6. Use of Biotreatment If only the"Yes"boxes were checked for all questions in Sections 2 and 5, or the project will have a recycled water system for non-potable use(Section 3),then the applicant may use appropriately designed bioretention facilities for compliance with C.3 treatment requirements.The applicant is encouraged to maximize infiltration of stormwater if site conditions allow. 7. Results of Screening Analysis Based on this screening analysis, the following steps will be taken for the project(check all that apply): ❑ Implement biotreatment measures (such as an appropriately designed bioretention area). ❑ Conduct further analysis of infiltration feasibility by completing the Infiltration Feasibility Worksheet. ❑ Conduct further analysis of rainwater harvesting and use(check one): ❑ Complete the Rainwater Harvesting and Use Feasibility Worksheet for: ❑ The entire project ❑ Individual building(s),if applicable, describe: ❑ Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for irrigation,based on Table 11 and the curves in Appendix F of the LID Feasibility Report ❑ Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for non-potable industrial use, based on the curves in Appendix F of the LID Feasibility Report. *For definitions,see Glossary(Attachment 1). Page 3 of 3 FINAL November 2011 Rainwater Harvesting and Use Feasibility Worksheet Municipal Regional Stormwater Permit(MRP) Stormwater Controls for Development Projects Complete this worksheet for all C.3 Regulated Projects* for which the project density exceeds the screening density* provided by municipal staff. Use this worksheet to determine the feasibility of treating the C.3.d amount of runoff*with rainwater harvesting and use for . indoor, non-potable water uses. Where it is infeasible to treat the C.3d amount of runoff with either harvesting and use or infiltration, stormwater may be treated with biotreatment* measures. See Glossary(Attachment 1)for definitions of terms marked with an asterisk(*). Complete this worksheet for the entire project area. If the project includes one or more buildings that each individually has a roof area of 10,000 square feet or more,complete a separate copy of this form for each of these buildings. 1. Enter Project Data. 1.1 Project Name: 2295 & 2305 S. Winchester Blvd. 1.2 Project address: 2295& 2305, S. Winchester Blvd. 1.3 Applicant/Agent Name: 1.4 Applicant/Agent Address: (For projects with a potential non-potable water use other than toilet flushing,skip to Question 5.1) 1.5 Project Type: Mixed Use If residential or mixed use,enter#of dwelling units: 16 1.6 Enter square footage of non-residential interior floor area.: 3,300 1.7 Potential rainwater capture area*: 22,052 sq.ft. 1.8 If it is a special Project*, indicate the percentage of LID treatment* reduction: percent (Item 1.8 applies only to entire project evaluations, not individual roof area evaluations.) 1.9 Total potential rainwater capture area that will require LID treatment: 22,052 0 sq.ft. (This is the total rain capture area remaining after any Special Project LID treatment reduction is applied.) - 2. Calculate Area of Self-Treating Areas,Self-Retaining Areas,and Areas Contributing to Self-Retaining Areas. (For areas within the Potential Rain Capture Area only) 2.1 Enter square footage of any self-treating areas* in the area that is being evaluated: ! sq.ft. 2.2 Enter square footage of any self-retaining areas* in the area that is being evaluated: sq.ft. 2.3 Enter the square footage of areas contributing runoff to self-retaining area*: sq.ft. -2.4 TOTAL of Items 2.1,2.2, and 2.3: _ - sq.ft. 3.Subtract credit for self-treating/self-retaining areas from area requiring treatment. 3.1 Subtract the TOTAL in Item 2.4 from the potential rainwater capture area in Item 1.9: - sq.ft. 3.2 Convert the remaining area required for treatment in Item 3.1 from square feet to acres: 0.51 0.00 acres 4. Determine feasibility of use for toilet flushing based on demand -4.1 Project's dwelling units per acre of adjusted potential rain capture area(Divide the number in 1.5 by dwelling the number in 3.2) units/acre Int.non-res. 4.2 Non-residential interior floor area per acre of adjusted potential rain capture area(Divide the.number in floor 1.6 by the number in 3.2) area/acre Note:formulas in Items 4.1 and 4.2 are set up,respectively,for a residential or a non-residential project.Do not use these pre-set formulas for mixed use projects. For mixed use projects,evaluate the residential toilet flushing demand based on the dwelling units per acre for the residential portion of the project(use a prorated acreage, based on the percentage of the project dedicated to residential use). Then evaluate the commercial toilet flushing demand per acre for the commercial portion of the project(use a prorated acreage,based on the percentage of the project dedicated to commercial use). Rainwater Harvestingp and Use Feasibilityy Worksheet See defimtioMs in Glossary(Attachment 1) 1 FINAL November 2011 i 4.3 Refer to the applicable countywide table in Attachment 2. Identify the number of dwelling units per impervious acre needed in your Rain Gauge Area to provide the toilet flushing demand required for dwelling . rainwater harvest feasibility. units/acre 4.4 Refer to the applicable countywide table in Attachment 2. Identify the square feet of non-residential int. no-1- interior floor area per impervious acre needed in your Rain Gauge Area to provide the toilet flushing res.floor demand required for rainwater harvest feasibility. area/a-re Check"Yes"or No"to indicate whether the following conditions apply. If"Yes"is checked for any question, then rainwater harvesting and use is infeasible. As soon as you answer"Yes",you can skip to Item 6.1. If"No"is checked for all items, then rainwater harvesting and Use is feasible and you must harvest and use the C.3.d amount of stormwater, unless you infiltrate the C.3.d amount of stormwater*. 4.5 Is the project's number of dwelling units per acre of adjusted area requiring treatment(listed in Item 4.1) ❑ Yes ❑ No LESS than the.number identified in Item 4.3? 4.6 Is the project's square footage of non-residential interior floor area per acre of adjusted area requiring ❑ No treatment(listed in Item 4.2) LESS than the number identified in Item 4.4? El Yes 5. Determine feasibility of rainwater harvesting and use based on factors other than demand. 5.1 Does the requirement for rainwater harvesting and use at the project conflict with local, state, ❑ Yes ❑ No or federal ordinances or building codes? 5.2 Would the technical requirements cause the harvesting system to exceed 2%of the Total Project Cost, or has the applicant documented economic hardship in relation to maintenance costs? (If so, attach an El Yes El No explanation.) 5.3 Do constraints, such as a slope above 10%or lack of available space at the site,make it infeasible to locate on the site a cistern of adequate size to harvest and use the C.3.d amount of water? (If so, attach El Yes El No an explanation.) 5.4 Are there geotechnical/stability concerns related to the surface(roof or ground)where a cistern would ❑ Yes ❑ No be located that make the use of rainwater harvesting infeasible? (If so, attach an explanation.) 5.5 Does the location of utilities, a septic system and/or heritage trees*limit the placement of a cistern on ❑ Yes ❑ No the site to the extent that rainwater harvesting is infeasible? (If so, attach an explanation.) - Note 1:It is assumed that projects with significant amounts of landscaping will either treat runoff with landscape dispersal(self-treating and self-retaining areas)or will evaluate the feasibility of havesting and using rainwater for irrigation using the curves in Appendix F of the LID Feasibility Report. 6. Results of Feasibility Determination Infeasible Feasible 6.1 Based on the results of the feasibility analysis in Item 4.4 and Section 5,rainwater harvesting/use is ❑ ❑ (check one): -� If"FEASIBLE"is indicated for Item 6.1 the amount of stormwater requiring treatment must be treated with harvesting/use, unless it is infiltrated into the soil. If"INFEASIBLE"is checked for Item 6.1, then the applicant may use appropriately designed bioretention*' facilities for compliance with C.3 treatment requirements. If Ksat> 1.6 in./hr., and infiltration is unimpeded by subsurface conditions, then the bioretention facilities are predicted to infiltrate 80%or more average annual runoff. If Ksat< 1.6, maximize infiltration of stormwater by using bioretention if site conditions allow, and remaining runoff will be discharged to storm drains via facility underdrains. If site conditions preclude infiltration,a lined bioretention area or flow-through planter may be used. Applicant(Print) Applicant(Sign) Date *See definitions in Glossary(Attachment 1) 2 FINAL November 2011 i Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program Attachment IV-1 Sizing for Flow-Based Treatment Controls CaliforniatowNP:Secaon'B Szing Flov BasedmCol bseontheTntonrB Handbook Flow'Approach � a This method uses the Rational Method equation to determine the design flow: Q=CIA Where: Q=the design flow in cubic feet per second(cfs), C=the drainage area runoff coefficient, I =the design intensity(in/hr), and A=the drainage area for the BMP(acres) Step 1. Determine the drainage area for the BMP,A= 0.56 acre Step 2 Determine the runoff coefficient,C= Q,73: om Table 3a or 3b It is more accurate to compute an area-weighted"C-factor"based on the surfaces in the drainage area(Table 3a), if possible,than to assume a composite"C-factor"such as those in Table 3b,especially for small drainage areas. Step 3. -Determine from Figure 1 the mean annual precipitation(MAPsite)at the project site location: (see Section II. Step 4 for more explanation.) G MAPsite= . 6 Q II1CheS Step 4 Identify the reference rain gage closest to the project site from the following list and record the MAPgage: MAPgage= .13 9`,i heS Reference Rain Mean Annual Gages Precipitation (MAPgage) (in) San Jose Airport 13.9 Palo Alto 13.7 Gilroy 18.2 Morgan Hill 19.5 Step 5 Determine the rain gage correction factor for the precipitation at the site using the information from Step 3 and Step 4. Correction Factor=MAPsite/MAPgage=(Step 3)/(Step 4) Correction Factor= 15 IV.Treatment Control Sizing Criteria Attachment IV-1—Page 2 FINAL :L,doevToms\G&DT1owwurkshcccduc May 20,2004 Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program Attachment IV-1 Sizing for Flow-Based Treatment Controls Step 6 Select the design intensity,I,for the reference gage closest to the site from the following list: I,Design Rainfall Intensity= -0.1 7 in/hou Gages 851h Percentile Hourly Design Rainfall Rainfall Intensity Intensity (in/hr) (I) (in/hr San Jose Airport 0.087 0.17 Palo Alto 0.096 0.19 Gilroy 0.11 0.21 Morgan Hill 0.12 0.24 The design intensity is twice the 0h percentile Hourly Rainfall'Intensity. Step 7. Determine the corrected design rainfall intensity(I)for the site:. Design intensity(site)=Correction factor*Design rainfall intensity for closest rain gage Design intensity(site)_(Step 5)* (Step 6)= 0.196 in/hr Step 8. Determine the design flow(Q)using the Rational Method equation: Q=C*I*A Q=(Step 2)* (Step 7) * (Step 1) Q='0.081 acres-in/hr Design Flow, Q = 0.082 efsi4l No conversion factor for correct units is needed for the rational formula because(I acre-in/hr)*(43,560 sq.ft/acre)*(Ift/12 in)*(lhr/3600 sec)xe 1 W/sec or cfs. IV.Treatment Control Sizing Criteria 1 Attachment IV-1—Page 3 FINAL JAandDev\Fom�s\G&D\F10 w kshcct.doc May 20,200^ C.3 Stormwater Handbook Santa Clara Valley Urban Runoff Pollution Prevention Program Table 3a—Estimated Runoff Coefficients for Various Surfaces During Small Storms (CDM,2003) Surface Runoff Coefficient (C Factor Concrete 0.80 Asphalt— 0.70 Pervious Concrete 0.60 Cobbles 0.60 Pervious Asphalt 0.55 Natural Stone without out 0.25 Turf Block 0.15 Brick(without rout) 0.13 Unit Pavers on Sand 0.10 Crushed Aggregate 0.10 Grass 0.10 ' Roofs(from WEF/ASCE, 1992) 0.75 Notes: The above C-factors were estimated by selecting the lower range of the best available C-factor for each paving surface.These C-factors are only appropriate for small storm treatment BMP design,and should not be used for flood control sizing.Where available,locally developed small storm C-factors for various surfaces should be used. Table 3b—Estimated Composite Runoff Coefficients for Small Storms'by Land Use(WEF/ASCE,2003) Description of Area Runoff Coefficient (C Factor Business: Neighborhood 0.50 Downtown 0.70 Residential: Single Family 0.30 Multi-unit,detached 0.40 Apartment 0.50 Multi-unit, attached 0.60 Industrial: Light 0.50 Heavy 0.60 Parks,cemeteries 0.10 Playgrounds 0.20 Unimproved 0.10 Notes: The above C-factors were estimated by selecting the lower range of the runoff coefficients listed for various land uses in WEF/ASCE, 1992.Where available,locally developed small storm C-factors for various land uses should be applied. 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''�'�� v ( 30 A Figure 1 Soil Texture and Mean �•_ � a _ 2s z. 16, Annual Precipitation Depths 4 � � for the Santa Clara Basin se'tc `� lot o Y Legend A t Soil Texture \ (NRCS Hydrologic Soil Group) F Clay(D) Street or Highway 0 Sandy Clay(D) N Stream =Clay Loam(D) 0 Jurisdictional Boundary ` 0 Silt Loam(B) o Rain Gage y Loam(B) 9 Mean Annual Precipitation Depths(Inches) _ OR AN- �,tilLi Data Source:Santa Clara Valley Water District a rw . Revised March 2004 i Santa Clem Valley Urba n Rrnaff 0 1 2 3 4 5 Miles Pro rba Pollution on Program i�! , t Santa Clara Valley Urban Runoff Pollution Prevention Program PROVISION C.3 DATA FORM Which Projects Must Comply with Stormwater Requirements? All projects that create and/or replace 10,000 sq.ft. or more of impervious surface on the project site must fill out this worksheet and submit it with the development project application. All restaurants,auto service facilities,retail gasoline outlets,and uncovered parking lot projects (stand-alone or part of another development project, including the top uncovered portion.of parking structures)that create and/or replace 5,000 sq.ft.or more of impervious surface on the project site must also fill out this worksheet. Interior remodeling projects,routine maintenance or repair projects such as re-roofing and re-paving, and single family homes that are not part of a larger plan of development are NOT required to complete this worksheet. What is an Impervious Surface? An impervious surface is a surface covering or pavement that prevents the land's natural ability to absorb and infiltrate rainfall/stormwater. Impervious surfaces include,but are not limited to rooftops, walkways,paved patios, driveways,parking lots, storage areas, impervious concrete and asphalt, and any other continuous watertight pavement or covering. Pervious pavement,underlain with pervious soil or pervious storage material(e.g., drain rock),that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal Regional Stormwater Permit(MRP),is not considered an impervious surface. For More Information For more information regarding selection of Best Management Practices for stormwater pollution prevention or stormwater treatment contact! 1. Project Information _ Project Name: 22958, 2305 S. Winchester Blvd. APN# 305-34-004/005 Project Address: 2295 & 2305 S. Winchester Blvd. Cross Streets: El Caminito Avenue Applicant/Developer Name: - Project Phase(s): of Engineer: Mark Knudsen / Kier & Wright Civil Engineers Project Type (Check all that apply): ❑ New Development ❑ Redevelopment ❑ Residential ❑ Commercial ❑ Industrial ❑ Mixed Use ❑ Public ❑ Institutional ❑ Restaurant ❑ Uncovered Parking ❑ Retail Gas Outlet ❑ Auto Service (SIC code) 0 Other (5013-5014,5541,7532-7534,7536-7539) Project Description: Construction mixed-use retail with residential above. Project Watershed/Receiving Water(creek, river or bay):Los Gatos Creek SCVURPPP C.3.Data-Form Page I of 4 November 2011 2. Project Size a.Total Site Area: b.Total Site Area Disturbed: 0.566 acre 0.574 acre (including clearing, grading,or excavating) z Proposed Area(f ) Total Post-Project Existing Area(ft) Replaced New Area(ftz) Impervious Area Roof 5,505 5,505 8,965 1/070 Parking 3,191 3,191 3,810 7;001 Sidewalks and Streets 2,799 581 0 581 c.Total Impervious Area 11,495 9,277 12,775 22,052- d.Total new and replaced impervious area 22,052 Pervious Area Landscaping 13,500 0 2,612 Pervious Paving 0 0 0 0 Other(e.g. Green Roof) 0 0 0 l) e.Total Pervious Area 13,500 0 2,612 f.Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious,area Existing Total Impervious Area) x 100% = 81% % 3. State Construction General Permit Applicability: a. Is#2.b. equal to 1 acre or more? ❑ Yes, applicant must obtain coverage under the State Construction General Permit. (i.e., file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see www.swreb.ca.gov/water issue s/programs/stormwatellconstruction.shtn .for det; ils). ❑ No, applicant does not need coverage under the State Construction General Permit. 4. MRP Provision C.3 Applicability: a. Is#2.d. equal to 10,000 sq. ft. or more, or 5,000 sq. ft. or more for restaurants, auto se vice facilities, retail gas outlets, and uncovered parking? ("Note that for public projects, the 5,000 sq.ft. threshold does not take effect until 1211112.) ❑ Yes, C.3. source control, site design and treatment requirements apply ❑ No, C.3. source control and site design requirements may.apply—check with local agency b. Is#2.f. equal to 50% or more? ❑ Yes, C.3. requirements (site design and source control, as appropriate, and stormwE ter treatment) apply to entire site ❑ No, C.3. requirements only apply to impervious area created and/or replaced 5. Hydromodification Management(HM)Applicability: a. Does project create and/or replace one acre or more of impervious surface AND is the i:otal post-project impervious area greater than the pre-project (existing) impervious area? ❑ Yes (continue) ❑ No-exempt from HM, go to page 3 b. Is the project located in an area of HM applicability(green area) on the HM Applicability Map? ( www.scvurpp12-w2k.conl/hmp maps.htm) ❑ Yes, project must implement HM requirements ❑ No, project is exempt from HM requirements SCVURPPP C.3.Data Form Page 2 of 4 November 201 1 6. Selection of Specific Stormwater Control Measures: Site Design Measures Source Control Measures Treatment Systems ❑ Minimize land disturbed ❑ Alternative building ❑ -None (all impervious surface materials drains to self-retaining areas) ❑ Minimize impervious _ surfaces ❑ Wash area/racks, drain to LID Treatment ❑ Minimum-impact street sanitary sewer2 ❑ Rainwater harvest and or parking lot design ❑ Covered dumpster area, use (e.g.,cistern or rain barrel drain to sanitary sewer sized for C.3.d treatment) ❑ Cluster structures/ pavement ❑ Sanitary sewer ❑ Infiltration basin ❑ Disconnected downspouts connection or accessible ❑ Infiltration trench cleanout for swimming ❑ Pervious pavement pool/spa/fountain2 ❑ Exfiltration trench ❑ Green roof ❑ Beneficial landscaping ❑ Underground detention (minimize irrigation,runoff, and infiltration system ❑ Microdetention in pesticides and fertilizers; (e.g.pervious pavement drain landscape promotes treatment) rock,large diameter conduit) ❑ Other self-treating area ❑ Outdoor material storage Biotreatment 3 ❑ Self-retaining area protection ❑ Bioretention area ❑ Rainwater harvesting and ❑ Covers, drains for loading ❑ Flow-through planter use (e.g.,rain barrel,cistern docks, maintenance bays, ❑ Tree box with connected to roof drains)1 fueling areas bioretentibn soils ❑ Preserved open space:. ❑ Maintenance(pavement ❑ Other ac. or sq. ft sweeping,catch basin .(circle one) cleaning,good housekeeping) ❑ Protected riparian and ❑ Storm drain labeling Other Treatment Methods Wetland areas/buffers ❑ Proprietary tree box.filter4 (Setback from top of bank: ❑ Other �) ❑ Media filter(sand,a compost, or proprietary media) ❑ Other ❑ Vegetated filter strips ❑ Dry detention basin ❑ Other Flow Duration Controls for Hydromodification Management(HM) ❑ Detention basin ❑ Underground ❑ Bioretention with outlet ❑ Other tank or vault control 'Optional site design measure; does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. 3 Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater harvest and use are infeasible. °These treatment measures are only allowed if the project qualifies as a"Special Project". 5 These treatment measures are only allowed as part of a multi-step treatment process. 5CVURPPP C.3.Data Form Page 3 of 4 November 2011 7. Treatment System Sizing for Projects with Treatment Requirements Indicate the hydraulic sizing criteria used and provide the calculated design flow or volume: Treatment System Component Hydraulic Sizing. Design Flow or Criteria Used3 Volume (cfs or cu.ft.) Biotreatment 2c 0.082 cfs 3Key: la: Volume—WEF Method lb: Volume—CASQA BMP Handbook Method 2a: Flow—Factored Flood Flow Method 2b: Flow—CASQA BMP Handbook Method 2c: Flow—.Uniform Intensity Method 3: Combination Flow and Volume Design Basis 8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third- party professional that is not a member of the project team or agency staff? ❑ Yes ❑ No Name of Reviewer 9. Operation &Maintenance Information A. Property Owner's Name B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M: a. Name: TBD b.. Address: TBD ' c. Phone/E-mail: TBD This section to be completed by Municipal staff. O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply: ❑ O&M Agreement ❑ Other mechanism that assigns responsibility(describe below): Reviewed: Community Development Department Public Works Department Planning Division: Engineering: Building Division: Other(Specify): Return form to: Data entry performed by: SCVURPPP C.3.Data Form Page 4 of 4 November 2011 Santa Clara Valley Urban Runoff Pollution Prevention Program PROVISION C.3 DATA FORM Which Projects Must Comply with Stormwater Requirements? All projects that create and/or replace 10,000 sq.ft. or more of impervious surface on the project site must fill out this worksheet and submit it with the development project application. All restaurants,auto service facilities, retail gasoline outlets,and uncovered parking lot projects (stand-alone or part of another development project, including the top uncovered portion of parking structures)that create and/or replace 5,000 sq.ft. or more of impervious surface on the project site must also fill out this worksheet. Interior remodeling projects,routine maintenance or repair projects such as re-roofing and re-paving, and single family homes that are not part of a larger plan of development are NOT required to complete this worksheet. What is an Impervious Surface? An impervious surface is a surface covering or pavement that prevents the land's natural ability to absorb and infiltrate rainfall/stormwater. Impervious surfaces include,but are not limited to rooftops, walkways,paved patios, driveways, parking lots, storage areas,impervious concrete and asphalt, and any other continuous watertight pavement or covering.Pervious pavement, underlain with pervious soil or pervious storage material(e.g., drain rock),that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal Regional Stormwater Permit(MRP),is not considered an impervious surface. For More Information For more information regarding selection of Best Management Practices for stormwater pollution prevention or stormwater treatment contact: 1. Project Information Project Name: 2295 & 2305 S. Winchester Blvd. APN# 305-34-004/005 Project Address: 2295 & 2305 S. Winchester Blvd. Cross Streets: El Caminito Avenue Applicant/Developer Name: Jeff Warmoth/SREA, Inc. Project Phase(s): 1 of 1 Engineer: Mark Knudsen / Kier & Wright Civil Engineers Project Type (Check all that apply): ❑ New Development ❑ Redevelopment ❑ Residential ❑ Commercial ❑ Industrial ® Mixed Use ❑ Public ❑ Institutional ❑ Restaurant ❑ Uncovered Parking ❑ Retail Gas Outlet ❑ Auto Service (SIC code) 0 Other (5013-5014,5541,7532-7534,7536-7539) Project Description: Construction mixed-use retail with residential above. Project Watershed/Receiving Water(creek, river or bay): Los Gatos Creek SCVURPPP C.3.Data Form Page I of 4 November 2011 � 1 2. Project Size a.Total Site Area: b.Total Site Area Disturbed: 0.566 acre 0.574 acre (including clearing,grin ,or excavating) H �� , Proposed Area a (ftz� Total Post-Project F � a �� wy„ Existing Area(ft) ft z Area ' � , Replaced New ( ) Impervious Area Roof 5,505 5,505 8,965 14,470 Parking 3,191 3,191 3,810 7,001 Sidewalks and Streets 2,799 581 0 581 c.Total Impervious Area 11,495 9,277 12,775 22,052 d.Total new and replaced impervious area 22,052 Pervious Area Landscaping 13,500 0 2,612 Pervious Paving 0 0 0 0 Other(e.g.Green Roof) 0 0 0 0 e.Total Pervious Area 13,500 0 2,612 f.Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious Area Existing Total Impervious Area) x 100% = 81% % 3. State Construction General Permit Applicability: a. Is#2.b. equal to 1 acre or more? ❑ Yes, applicant must obtain coverage under the State Construction General Permit (i.e., file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see www.swrcb.ca.gov/water issues/ rroograms/stormwater/construction.shtml for details). ® No, applicant does not need coverage under the State Construction General Permit. 4. MRP Provision C.3 Applicability: a. Is#2.d. equal to 10,000 sq. ft. or more, or 5,000 sq. ft. or more for restaurants, auto service facilities, retail gas outlets, and uncovered parking? (*Note that for public projects, the 5,000 sq.ft. threshold does not take effect until•1211112.) ® Yes, C.3. source control, site design and treatment requirements apply ❑ No, C.3. source control and site design requirements may apply—check with local agency b. Is#2.f. equal to 50%or more? N Yes, C.3. requirements (site design and source control, as appropriate, and stormwater treatment) apply to entire site ❑ No, C.3. requirements only apply to impervious area created and/or replaced 5. Hydromodification Management(HM) Applicability: a. Does project create and/or replace one acre or more of impervious surface AND is the total post-project impervious area greater than the pre-project (existing) impervious area? ❑ Yes (continue) ® No—exempt from HM, go to page 3 b. Is the project located in an area of HM applicability(green area) on the HM Applicability Map? ( www.scvuEppp-w2k.com/hmp—iiiaps.htm) ❑ Yes, project must implement HM requirements N No,project is exempt from HM requirements SCVURPPP C.3.Data Form Page 2 of 4 November 2011 6. Selection of Specific Stormwater Control Measures: Site Design Measures Source Control Measures Treatment Systems ❑ Minimize land disturbed ❑ Alternative building ❑ None (all impervious surface ❑ Minimize impervious materials drains to self-retaining areas) surfaces ❑ Wash area/racks, drain to LID Treatment ❑ Minimum-impact street sanitary sewers ❑ Rainwater harvest and or parking lot design ❑ Covered dumpster area, use (e.g.,cistern or rain barrel ❑ Cluster structures/ drain to sanitary sewer sized for C.3.d treatment) pavement ❑ Sanitary sewer ❑ Infiltration basin ❑ Disconnected downspouts connection or accessible ❑ Infiltration trench cleanout for swimming ❑ Pervious pavement pool/spa/fountain2 ❑ Exfiltration trench ❑ Green roof ❑ Beneficial landscaping ❑ Underground detention and infiltrations stem ❑ Microdetention in (minimize irrigation,runoff, (e.g.pervious pavement drain pesticides and fertilizers; landscape promotes treatment) rock,large diameter conduit) M Other self-treating area ❑ Outdoor material storage Biotreatment 3 . ❑ Self-retaining area protection M Bioretention area ❑ Rainwater harvesting and ❑ Covers, drains for loading ❑ Flow-through planter use (e.g.,rain barrel,cistern docks, maintenance bays, ❑ Tree box with connected to roof drains)1 fueling areas bioretention soils ❑ Preserved open space: M Maintenance(pavement ❑ Other ac. or sq. ft sweeping;catch basin .(circle one) cleaning,good housekeeping) ❑ Protected riparian and ❑ Storm drain labeling Other Treatment Methods wetland areas/buffers ❑ Proprietary tree box filter' (Setback from top of bank: ❑ Other ft.) ❑ Media filter(sand,compost, ❑ Other or proprietary media)4 ❑ Vegetated filter strips ❑ Dry detention basins ❑ Other Flow Duration Controls for Hydromodification Management(HM) ❑ Detention basin ❑ Underground ❑ Bioretention with outlet ❑ Other tank or vault control 'Optional site design measure;does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. s Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater harvest and use are infeasible. 4 These treatment measures are only allowed if the project qualifies as a"Special Project". 5 These treatment measures are only allowed as part of a multi-step treatment process. 1 SCVURPPP C.3.Data Form Page 3 of 4 November 2011 r 7. Treatment System Sizing for Projects with Treatment Requirements Indicate the hydraulic sizing criteria used and provide the calculated design flow or volume: Treatment System Component Hydraulic Sizing Design Flow or Criteria Used Volume (cfs or cu.ft.) Biotreatment 2c 0.082 cfs 3Key: 1 a: Volume—WEF Method lb: Volume—CASQA BMP Handbook Method 2a: Flow—Factored Flood Flow Method 2b: Flow—CASQA BMP Handbook Method 2c: Flow—Uniform Intensity Method 3: Combination.Flow and Volume Design Basis 8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third- party professional that is not a member of the project team or agency staff? ❑ Yes © No Name of Reviewer 9. Operation & Maintenance Information A. Property Owner's Name Jeff Warmoth B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M: a. Name: Jeff Warmoth b. Address: P.O. Box 1001 Los Altos, CA 94023 c. Phone/E-mail: jeffwarmoth@gmail.com This section to be completed by Municipal staff. O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply: ❑ O&M Agreement ❑ Other mechanism that assigns responsibility(describe below): Reviewed: Community Development Department Public Works Department Planning Division: Engineering: Building Division: Other{Specify): Return form to: Data entry performed by: SCVURPPP C.3.Data Form Page 4 of 4 November 2011 �woc)c� D ri c m m rn X Z n-0cn- C ..,., z rm �v r O mtnrmm vO,v,,—zi- = . M 0 0. z Vl z z N A 0 .Q T P_3 I P_1 w N Ln ° r- 2295 -2305 S WINCHESTER BLVD jw� KIER & WRIGHT D -WG c HYDRAULIC C MAP CIVIL ENGINEERS & SURVEYORS, INC. In CAMPBELL o m SREA INC. 3350 Scott Boulevard,Building 22 (408)727 6665 m oN Santa Clara,California 95054 fax(408)727 5641 S WINCHESTER BLVD J. T V1 CALIFORNIA f 1 DN% 'Santa Clara Valley Urban Runoff Pollution Prevention Program PROVISION C.3 DATA FORM Which Projects Must Comply with Stormwater Requirements? All projects that create and/or replace 10,000 sq.ft..or more of impervious surface on the project site must fill out this worksheet and submit it with the development project application. All restaurants,auto service facilities,retail gasoline outlets,and uncovered parking lot projects (stand-alone or part of another development project,including the top uncovered portion of parking structures)that create and/or replace 5,000 sq.ft. or more of impervious surface on the project site must also fill out this worksheet. Interior remodeling projects,routine maintenance or repair projects such as re-roofing and re-paving, and single family homes that are not part of a larger plan-of development are NOT required to complete this worksheet. What is an Impervious Surface? An impervious surface is a surface covering or pavement that prevents the land's natural ability to absorb and infiltrate rainfall/stormwater. Impervious surfaces include,but are not limited to rooftops, walkways,paved patios, driveways,parking lots, storage areas,impervious concrete and asphalt, and any other continuous watertight pavement or covering. Pervious pavement,underlain with pervious soil or pervious storage material(e.g.,drain rock),that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas_ OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal Regional Stormwater Permit(MRP),is not considered an impervious surface. For More Information For more information regarding selection of Best Management Practices for stormwater pollution prevention or stormwater treatment contact: 1._ Project Information Project Name: 2295 & 2305 S. Winchester Blvd. APN# 305-34-004/005 Project Address: 2295 & 2305 S. Winchester Blvd. Cross Streets: El Caminito Avenue Applicant/Developer Name: Jeff Warmoth/SREA, Inc. Project Phase(s): of 1 Engineer: Mark Knudsen / Kier& Wright Civil Engineers Project Type(Check all that apply): ❑ New Development ❑ Redevelopment ❑ Residential ❑ Commercial ❑ Industrial N Mixed Use ❑ Public ❑ Institutional ❑ Restaurant ❑ Uncovered Parking ❑ Retail Gas Outlet ❑ Auto Service(SIC code) 0 Other (5013-5014,5541,7532-7534,7536-7539) Project Description: Construction mixed-use retail with residential above. Project Watershed/Receiving Water(creek, river or bay):Los Gatos Creek S&V PPP C.3.Data Form Page 1 of 4 November 2011 I \1 t 1 2.Project Size a.Total Site Area: b.Total Site Area Disturbed: 0.566 acre . 0.574 acre (including clearin.-,g9rin ,or excavating) z Proposed Area Total Post-Project „4,,, Existing Area(ft) 9 Replaced New Area(ft?) � Impervious Area Roof 5,505 5,505 81965. 14,470 Parking 3,191 3,191 3,810 7,001 Sidewalks and Streets 2,799 581 0 581 , c.Total Impervious Area 11,495 9,277 12,775 . 22,052 d.Total new and replaced impervious area 22,052 Pervious Area Landscaping 13,500 0 -2,612 Pervious Paving 0 0 0 0 Other(e.g.,Green Roof) 0 0 0 0 e.Total Pervious Area 13,500 0 2,612 f.Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious Area Existing Total Impervious Area) x 100% = 81% % 3. State Construction General Permit Applicability: a. Is#2.b. equal to 1 acre or more? ❑ Yes, applicant must obtain coverage under the State Construction General Permit (i.e., file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see www swrcb ca gov/water issues/programs/stormwater/construction.sbtml.for details). N No, applicant does not need coverage under the State Construction General Permit. 4. MRP Provision C.3 Applicability: a. Is##24. equal to 10,000 sq. ft. or more, or 5,000 sq. ft or more for restaurants, auto service facilities,retail gas outlets, and uncovered parking? (Note that for public projects, the 5,000 sq.ft. threshold does not take effect until 1211112.) N Yes, C.3. source control,,site design and treatment requirements apply ❑ No, C.3. source control and site design requirements may apply—check with local agency b. Is#2.f. equal to 50% or more? N Yes, C.3.requirements (site design and source control, as appropriate, and stormwater treatment) apply to entire site ❑ No, C.3. requirements only apply to impervious area created and/or replaced 5. Hydromodification Management(HM) Applicability: a. Does project create and/or replace one acre or more of impervious surface AND is the total post-project impervious area greater than the pre-project (existing) impervious area? ❑ Yes (continue) N No—exempt from HM, go to page 3 b. Is the project located in an area of HM applicability (green area) on the HM Applicability Map? ( www.scvul-ppp-w2k.com/hmp maps.htm) ❑. Yes,project must implement HM requirements N No,project is exempt from HM requirements SCVURPPP C.3.Data Form Page 2 of 4 November 2011 6. 'Selection of Specific Stormwater Control Measures: Site Design Measures Source Control Measures Treatment Systems ❑ Minimize land disturbed ❑ Alternative building ❑ None (all impervious surface ❑ Minimize impervious materials drains to self-retaining areas) surfaces ❑ Wash area/racks, drain to LID Treatment ❑ Minimum-impact street sanitary sewer2 ❑ Rainwater harvest and or parking lot design ❑ Covered dumpster area, use (e.g.,cistern or rain barrel ❑ Cluster structures/ drain to sanitary sewer'" sized for C.3.d treatment) pavement ❑ Sanitary sewer 0 Infiltration basin ❑ Disconnected downspouts connection or accessible ❑ Infiltration trench cleanout for swimming ❑ Pervious pavement pool/spa/fountain2 ❑ Exfiltration trench ❑ Green roof ❑ Beneficial landscaping ❑ Underground detention (minimize irrigation,runoff, and infiltration system ❑ Microdetention in pesticides and fertilizers; (e.g.pervious pavement drain landscape promotes treatment) rock,large diameter conduit) ® Other self-treating area ❑ Outdoor material storage Biotreatment 3 ❑ Self-retaining area protection ® Bioretention area ❑ Rainwater harvesting and ❑ Covers, drains for loading ❑ Flow-through planter use (e.g.,rain barrel,cistern docks, maintenance bays, ❑ Tree box with connected to roof drains)1 fueling areas bioretention soils ❑ Preserved open space: ® Maintenance (pavement ❑ Other ac. or sq. ft sweeping,catch basin .(circle one) cleaning,good housekeeping) ❑ Protected riparian and ❑ Storm drain labeling Other Treatment Methods wetland areas/buffers ❑ Proprietary tree box filter' (Setback from top of bank: ❑ Other ft) ❑ Media filter(sand,compost, or proprietary media)4 ❑ Other ❑ Vegetated filter strips ❑ Dry detention basins ❑ Other Flow Duration Controls for Hydromodification Management(HW ❑ Detention basin ❑ Underground ❑ Bioretention with outlet ❑ Other tank or vault control t Optional site design measure; does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. 3 Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater harvest and use are infeasible. 'These treatment measures are only allowed if the project qualifies as a"Special Project". - 5 These treatment measures are only allowed as part of a multi-step treatment process. SCVURPPP C.3.Data Form Page 3 of 4 November 2011 7. Treatment System Sizing fQr:Projects with Treatment Requirements Indicate the hydraulic sizing criteria used and provide the calculated design flow or volume: Treatment System Component Hydraulic Sizing Design Flow or Criteria Used Volume (cfs or cu.ft.) Biotreatment 2c 0.082 cfs 3Key: la: Volume—WEF Method IN Volume—CASQA BMP Handbook Method 2a:Flow—Factored Flood Flow Method 2b: Flow-CASQA BMP Handbook Method 2c: Flow-Uniform Intensity Method . 3: Combination Flow and Volume Design Basis 8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third- party professional that is not a member of the project team or agency staff? - ❑ Yes © No Name of Reviewer 9. Operation &Maintenance.Information A. Property Owner's Name Jeff Warmoth _ B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M: a. Name: Jeff Warmoth b. Address: P.O. Box 1001 Los Altos, CA 94023 C. Phone/E-mail: jeffwarmoth@gmail.com This section to be completed by Municipal staff. O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply: 13 , O&M Agreement ❑ Other mechanism that assigns responsibility(describe below): - Reviewed: Community Development Department Public Works Department Planning Division: Engineering: Building Division: Other(Specify): Return form to: Data entry performed by: SCVURPPP C.3.Data Form Page 4 of 4 November 2011 --Santa Clara Valley C 3 Stormwater Handbook Urban Runoff. Pollution Prevention Program Attachment IV-1 Sizing for Flow-Based Treatment Controls Section B—Sizing Flow Based Treatment Controls based on the Cal forn'a Stb�mwater BMP M= Handbook FZ1'6w Approach_ This method uses the Rational Method equation-to determine the design flow: - Q=CIA Where: Q=the design flow in cubic feet per second(cfs), C=the drainage area runoff coefficient, I =the design intensity(in/hr),and A=the drainage area for the BMP(acres) Step 1. Determine the drainage area for the BMP,A= 0.5,6&acrc Step 2 Determine the runoff coefficient,C= 073'from Table 3a or 3b It is more accurate to compute an area-weighted"C-factor"based on the surfaces in the drainage area(Table 3a),if possible,than to assume a composite"C-factor"such as those in Table 3b,especially for small drainage areas. . Step 3. Determine from Figure 1 the mean annual precipitation(MAPsiSe)at the project site location: (see Section Il. Step 4 for more explanation.) MAPsite= 16.0,inches Step 4 Identify the reference rain gage closest to the project site from the following list and record the MAPgage: MAPgage=1 13.9,inches Reference Rain Mean Annual Gages Precipitation(MAPgage) (in) San Jose Airport 13.9 Palo Alto 13.7 Gilroy 18.2 Morgan Hill 19.5 Step 5 Determine the rain gage correction factor for the precipitation at the site using-the information from Step 3-and Step 4. Correction Factor=MAPsite/MAPgage=(Step 3)/(Step 4) Correction Factor IV.Treatment Control Sizing Criteria Attachment IV-1—Page 2 FINAL 1:\L=dDevTo=\G&DT1oww ksheet.dm May 20,2004 . Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program Attachment IV-1 Sizing for.Flow-Based Treatment Controls nk Flnw Ann tied) Step 6 Select the design intensity,I,for the reference gage closest to the site from the following list: I,Design Rainfall Intensity= ' -0.1.7 °r rpa,in%ho Gages 851h Percentile Hourly Design Rainfall Rainfall Intensity Intensity (in/hr) (I) (in/hr San Jose Airport 0.087 0.17 Palo Alto 0.096 0.19 Gilroy 0.11 0.21 Morgan Hill 0.12 0.24 The design intensity is twice the 85`h percentile Hourly Rainfall Intensity. Step 7. Determine the corrected design rainfall intensity(1)for the site: Design intensity(site)=Correction factor.*Design rainfall intensity for closest rain gage Design intensity(site)=(Step 5) * (Step 6)= -0196 ''- in/hr Step 8. Determine the design flow(Q)using the Rational Method equation: Q=Q*I*A Q=(Step 2)* (Step 7) * (Step 1) Q= 0.081 acres-in/hr Design Flow, Q = O 08Z e£s i 1 No conversion factor for correct units is needed for the rational formula because(1 acre-in/hr)*(43,560 sq.ft/acre)*(lft/12 in)*(lhr/3600 sec) 1 ft3/sec or efs. IV.Treatment Control Sizing Criteria Attachment IV-1—Page 3 FINAL JAL-dD-\Forms\G&D\F1--kshe.W- May 20,2004 C.3 Stormwater Handbook :Santa Clara Valley Urban Runoff . Pollution.Prevention Program Table 3a—Estimated Runoff Coefficients for Various Surfaces During Small Storms(CDM,2003) Surface Runoff Coefficient (C Factor) Concrete 0.80 Asphalt 0.70 Pervious Concrete 0.60 Cobbles 0.60 Pervious.As halt 0.55 Natural Stone without rout 0.25 Turf Block 0.15 Brick without rout 0.13 Unit Pavers on Sand 0.10 - _ Crushed Aggregate 0.10 Grass 0.10 Roofs (from WEF/ASCE, 1992) 0.75 Notes: The above C-factors were estimated by selecting the lower range of the best available C-factor for each paving surface.These C-factors are only appropriate for small storm treatment BMP design,and should not be used for flood control sizing.Where available,locally developed small storm C-factors for various surfaces should be used. Table 3b—Estimated Composite Runoff Coefficients for Small Storms by Land Use(WEF/ASCE,2003) Description of Area Runoff Coefficient (C Factor) Business: Neighborhood 0.50 Downtown 0.70 Residential: Single Family 0.30 Multi-unit,detached 0.40 Apartment 0.50 Multi-unit, attached 0.60 Industrial: Light 0.50 Heavy 0.60 Parks,cemeteries 0.10 Playgrounds 0.20 Unimproved 0.10 Notes: The above C-factors were estimated by selecting the lower range of the runoff coefficients listed for various land uses in WEF/ASCE, 1992.Where available,locally developed small storm C-factors for various land uses should be applied. IV.Treatment Control Sizing Criteria Attachment IV-1—Page 1 FINAL ]:\LaedDev\Farms\G&D\F1ow worksheet.doc May 20,2004 - t ` YAN Ua3d. . �, ��� �.8s �a ��• � �,�°.� � �'it' �$a'��, ter«s '`�,�., � b�:= y , } # ` ?� NMI .i f .�� `� .O ❑ ����" �A Ly� za' � a�t�s.� �� ���i^�`�yJ E��S 4 �q•" � 4� ,t °b r ii ``.+ <r,y � -28 Figure 1 -° Soil Texture.and Mean Annual Precipitation Depths ��� � t4 " s Y for the Santa Clara Basin SOENfOSGgF Legend Soil Texture 1 9 ;; 13D (NRCS Hydrologic Soil Group) rt f 28 Clay(D) N Street or Highway , . 0 Sandy Clay(D) N Stream Clay Loam(D) Jurisdictional Boundary 0 Silt Loam(B) o Rain Gage e 0 Loam(B) ,,t'Mean Annual Precipitation Depths(Inches) Data Source:Santa ciara Valley Water District _ N Revised March 2004 Santa Gera valley 4 s y Urban Runoff 0 7 2 3 4 5 Miles Pollution Prevention Program ' Ml Santa ara Urban Runoff unoff Valley Pollution Prevention Program Infiltration/Harvesting and Use Feasibility Screening Worksheet Apply these screening criteria for C.3 Regulated Projects*required to implement Provision C.3 stormwater treatment requirements. See the Glossary(Attachment 1)for definitions of terms marked with an asterisk("). Contact municipal staff to determine whether the project meets Special Project*criteria. If the project meets Special Project criteria, it may receive LID treatment reduction credits. 1. Applicant Info Site Address: 2295 & 2305 S. Winchester Blvd. CA APN: 305-34-004/005 Applicant Name: Jeff Warmoth/SREA Inc. Phone No.: 650-400-6293 -Mailing Address: P.0. BOX 1001 Los Altos, CA 94023 2. Feasibility Screening for Infiltration Do site soils either(a)have a saturated.hydraulic conductivity*(Ksat)that will NOT allow infiltration of 80%of the annual'runoff(that is,the Ksat is LESS than 1.6 inches/hour),or,if the Ksat rate is not available, (b)consist of Type C or D soils?' N Yes(continue) ❑ No—complete the Infiltration Feasibility Worksheet.If infiltration of the C.3.d amount of runoff is found to be feasible,there is no need to complete'the rest of this screening worksheet. 3. Recycled Water Use Check the box if the project is installing and using a recycled water plumbing system for non-potable water use. ❑ The project is installing a recycled water plumbing system,and installation of a second non-potable water system for harvested rainwater is impractical,and considered infeasible due to cost considerations. Skip to Section 6. 4. Calculate the Potential Rainwater Capture Area*for Screening of Harvesting and Use Complete this section for the entire project area. If rainwater harvesting and use is infeasible for the entire site, and the project includes one or more buildings that each have an individual roof area of 10,000 sq.ft. or more, then complete Sections 4 and 5 of this form for each of these buildings. 4.1 Table 1 for(check one): d The whole project ❑ Area of I building roof(10,000 sq.ft.min.) Table 1: Calculation of the Potential Rainwater Capture Area* The Potential Rainwater Capture Area may consist of either the entire project area or one building with a roof urea of 10,000 sq.ft.or more. 1 2 3 4 Pre-Project Proposed Impervious Surface (Is),in Post-project Impervious surface2 sq.ft. landscaping (sq.ft.),if applicable Replaced Is Created°IS (sq.ft.),if applicable a.Enter the totals for the area to be evaluated: 11,495 9,277 12,775 1 2,612 b.Sum of replaced and created impervious surface: N/A 22,052 N/A a Area of existing impervious surface that will NOT be replaced by the project. 0- Base this response on the site-specific soil report,if available.If this is not available,consult soil hydraulic conductivity maps in Attachment 3. Z,Enter the total of all impervious surfaces,including the building footprint,driveway(s),patio(s),impervious deck(s),unroofed porch(es),uncovered parking lot(including top deck of parking structure),impervious trails,miscellaneous paving or structures,and off-lot impervious surface(new,contiguous impervious surface created from road projects,including sidewalks and/or bike lanes built as part of new street).Impervious surfaces do NOT include vegetated roofs or pervious pavement that stores and infiltrates rainfall at a rate equal to immediately surrounding,unpaved landscaped areas,or that stores and infiltrates the C.3.d amount of runoff*. 3"Replaced"means that the project will install impervious surface where existing impervious surface is removed. ""Created"means the project will install new impervious surface where there is currently no impervious surface. °For definitions,see Glossary(Attachment 1). Page I of 3 FINAL November 2011 hifiltration/Harvesting and Use Feasibility Screening Worksheet 4.2 Answer this question ONLY if you are completing this section for the entire project area. If existing impervious surface_will be replaced by.the project, does the area to be replaced equal 50% or more of the existing area of impervious surface-? (Refer to Table 1,Row "a". Is the area in Column 2.>50%of Column I?) ® Yes,C.3.stormwater treatment requirements apply to areas of impervious surface that will remain in place as well as the area created and/or replaced.This is known as the 50%rule. ❑ No,C.3.requirements apply only to the impervious area created and/or replaced. 4.3 Enter the square footage of the Potential Rainwater Capture Area*.If you are evaluating only the roof area of a building, or you answered"no" to Question 4.2,this amount is from Row"b"in Table 1. If you answered"yes" to Question 4.2,this amount is the sum of Rows"b"and"c"in Table 1.: 22,052 square feet. 4.4 Convert the measurement of the Potential Rainwater Capture Area* from square feet to acres (divide the amount in Item 4.3 by 43,560): 0.51 acres. 5. Feasibility Screening for Rainwater Harvesting and Use 5.1 Use of harvested rainwater for landscape irrigation: Is the onsite landscaping LESS than 2_5 times the size of the Potential Rainwater Capture Area* (Item 4.3)? (Note that the landscape area(s)would have to be contiguous and within the same Drainage Management Area to use harvested rainwater for irrigation via gravity flow:) ® Yes(continue) ❑ No - Direct runoff from impervious areas to self-retaining areas*OR refer to Table 11 and the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for irrigation. 5.2 Use of harvested rainwater for toilet flushing or non-potable industrial use: a. Residential Proiects:Proposed number of dwelling units: 16 du Calculate the dwelling units per impervious acre by dividing the number of dwelling units by the acres of the Potential Rainwater Capture Area*in Item 4.4. Enter the result here: 32 Is the number of dwelling units per impervious acre LESS than 100(assuming 2.7 occupants/unit)? ® Yes(continue) ❑ No— complete the Harvest[Use Feasibility Worksheet. b. Commercial/Industrial Projects:Proposed interior floor area: 3,300 (sq.ft.) Calculate the proposed interior floor area(sq.ft.)per acre of impervious surface by dividing the interior floor area(sq.ft.)by the acres of the Potential Rainwater Capture Area*in Item 4.4. Enter the result here: 6,471 Is the square footage of the interior floor space per impervious acre LESS than 70,000 sq.ft.? N Yes(continue) ❑ No—complete the Harvest/Use Feasibility Worksheet c. School Projects:Proposed interior floor area: (sq.ft.) Calcul"ate the proposed interior floor,area per acre of impervious surface by dividing the interior floor area (sq.ft.)by the acres of the Potential Rainwater Capture Area*in Item 4.4.Enter the result here: Is the square footage of the interior floor space per impervious acre LESS than 21,000 sq.ft.? ❑ Yes(continue) ❑ No—complete the Harvest/Use.Feasibility Worksheet *For definitions,see Glossary(Attachment 1). Page 2 of 3 FINAL November 2011 Lafzlt-ation/Harvesting and Use Feasibility Screening Worksheet d. Mixed Commercial and Residential Use Projects • Evaluate the residential toilet flushing demand based on the dwelling units per impervious acre for the residential portion of the project,following the instructions in Item 5.2.a,except you will use a prorated acreage of impervious surface,based on the percentage of the project dedicated to residential use. • Evaluate the commercial toilet flushing demand per impervious acre for the commercial portion of the project,following the instructions in Item 5.2.a,except you will use a prorated acreage of impervious surface, based on the percentage of the project dedicated to commercial use. e. Industrial Projects:Estimated non-potable water demand(gal/day): Is the non-potable demand LESS than 2,400 gal/day per acre of the Potential Rainwater Capture Area? ❑ Yes(continue) '❑ . No= refer to the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for industrial use. 6. Use of Biotreatment If only the"Yes"boxes were checked for all questions in Sections 2 and 5,or the project will have a recycled water system for non-potable use(Section 3),then the applicant may use appropriately designed bioretention facilities for compliance with C.3 treatment requirements.The applicant is encouraged to maximize infiltration of stormwater if site conditions allow. 7. Results of Screening Analysis Based on this screening analysis,the following steps will be taken for the project(check all that apply): ® Implement biotreatment measures(such as an appropriately designed bioretention area). ❑ Conduct further analysis of infiltration feasibility by completing the Infiltration Feasibility Worksheet. ❑ Conduct further analysis of rainwater harvesting and use(check one): ❑ Complete the Rainwater Harvesting and Use Feasibility Worksheet for: ❑ The entire project ❑ Individual building(s),if applicable,describe: ❑ Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for irrigation,based on Table 11 and the curves in Appendix F of the LID Feasibility Report ❑ Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for non-potable industrial use, based on the curves in Appendix F of the LID Feasibility Report. *For definitions,see Glossary(Attachment 1). Page 3 of 3 FINAL November 2011