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Home My WebLink AboutCDP 06-25; Hagey Residence; Storm Water Management Plan; 2009-03-03Storm Water Management Plan Hagey Residence Jefferson Street Carlsbad, CA APN: 155-140-37 & -38 CDP 06-25 GRADING PLAN 458-3A SCANNED RECORD COPY Initial Date Prepared By: Sampo Engineering, Inc. 1034 Second Street Encinitas, CA 92024 APPENDIX A STORM WATER STANDARDS QUESTIONNAIRE I INSTRUCTIONS: This questionnaire must be completed by the applicant in advance of submitting for a development application (subdivision and land use planning approvals and construction permits). The results of the questionnaire determine the level of storm water pollution prevention standards applied to a proposed development or redevelopment project. Many aspects of project site design are dependent upon the storm water pollution protection standards applied to a project. Applicant responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City staff has responsibility for making the final assessment after submission of the development application. A staff determination that the development application is subject to more stringent storm water standards, than initially assessed by the applicant, will result in the return of the development application as incomplete. If applicants are unsure about the meaning of a question or need help in determining how to respond to one or more of the questions, they are advised to seek assistance from Engineering Department Development Services staff. A separate completed and signed questionnaire must be submitted for each new development application submission. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. In addition to this questionnaire, applicants for construction permits must also complete, sign and submit a Construction Activity Storm Water Standards Questionnaire. To address pollutants that may be generated from new development, the City requires that new development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management Practices (BMPs) into the project design, which are described in Chapter 2 of the City's Storm Water Standards Manual This questionnaire should be used to categorize new development and significant redevelopment projects as priority or non-priority, to determine what level of storm water standards are required or if the project is exempt. | 1. Is your project a significant redevelopment? Definition: Significant redevelopment is defined as the creation, addition or replacement of at least 5,000 square feet of impervious surface on an already existing developed site. Significant redevelopment includes, but is not limited to: the expansion of a building footprint; addition to or replacement of a structure; structural development including an increase in gross floor area and/or exterior construction remodeling; replacement of an impervious surface that Is not part of a routine maintenance activity; and land disturbing activities related with structural or impervious surfaces. Replacement of impervious surfaces includes any activity that is not part of a routine maintenance activity where impervious material(s) are removed, exposing underlying soil during construction. Note: If the Significant Redevelopment results in an increase of less than fifty percent of the impervious surfaces of a previously existing development, and the existing development was not subject to SUSMP requirements, the numeric sizing criteria discussed in Table 3 of 2.3.3.4 applies only to the addition, and not to the entire development. 2. If your project IS considered significant redevelopment, then please skip Section 1 and proceed with Section 2. 3. If your project IS NOT considered significant redevelopment, then please proceed to Section 1. 21 SWMP Rev 6/4/08 I SECTION 1 NEW DEVELOPMENT PRIORITY PROJECT TYPE Does you project meet one or more of the following criteria: 1. Home subdivision of 100 units or more. Includes SFD, MFD, Condominium and Apartments 2. Residential develooment of 10 units or more. Includes SFD, MFD, Condominium and Apartments 3. Commercial and industrial development creator than 100.000 sguare feet includina oarkina areas. Any development on private land that is not for heavy industrial or residential uses. Example: Hospitals, Hotels, Recreational Facilities, Shopping Malls, etc. 4. Heavy Industrial I Industry greater than 1 acre (NEED SIC CODES FOR PERMIT BUSINESS TYPES) SIC codes 5013, 5014, 5541, 7532-7534, and 7536-7539 5. Automotive repair shoo. SIC codes 5013, 5014, 5541, 7532-7534, and 7536-7539 6. A New Restaurant where the land area of development is 5,000 souare feet or more including parking areas. SIC code 581 2 7. Hillside development (1) greater than 5,000 square feet of impervious surface area and (2) development will grade on any natural slope that is 25% or greater 8. Environmentally Sensitive Area (ESA). Impervious surface of 2,500 square feet or more located within, "directly adjacent"2 to (within 200 feet), or "discharging directly to"3 receiving water within the ESA1 9. Parking lot. Area of 5,000 square feet or more, or with 15 or more parking spaces, and potentially exposed to urban runoff 10. Retail Gasoline Outlets - serving more than 100 vehicles oer day Serving more than 100 vehicles per day and greater than 5,000 square feet 11. Streets, roads, driveways, highways, and freeways. Project would create a new paved surface that is 5,000 square feet or greater. 12. Coastal Development Zone. Within 200 feet of the Pacific Ocean and (1) creates more than 2500 square feet of impermeable surface or (2) increases impermeable surface on property by more than 10%. YES ^ NO ^ ^ y ^ v/ / / v/ / <** / 1 Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodies designated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and Count of San Diego; and any other equivalent environmentally sensitive areas which have been identified by the Copermittees. 2 "Directly adjacent" means situated within 200 feet of the environmentally sensitive area. 3 "Discharging directly to" means outflow from a drainage conveyance system that is composed entirely of flows from the subject development or redevelopment site, and not commingled with flow from adjacent lands. Section 1 Results: If you answered YES to ANY of the questions above you have a PRIORITY project and PRIORITY project requirements DO apply. A Storm Water Management Plan, prepared in accordance with City Storm Water Standards, must be submitted at time of application. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3. If you answered NO to ALL of the questions above, then you are a NON-PRIORITY project and STANDARD requirements apply. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3. SWMP Rev 6/4/08 SECTION 2 SIGNIFICANT REDEVELOPMENT: 1. Is the project redeveloping an existing priority project type? (Priority projects are defined in Section 1) YES NO ^ If you answered YES, please proceed to question 2. If you answered NO, then you ARE NOT a significant redevelopment and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. 2. Is the project solely limited to one of the following: a. Trenching and resurfacing associated with utility work? b. Resurfacing and reconfiguring existing surface parking lots? c. New sidewalk construction, pedestrian ramps, or bike lane on public and/or private existing roads? d. Replacement of existing damaged pavement? ^ ^ ^^~ If you answered NO to ALL of the questions, then proceed to Question 3. If you answered YES to ONE OR MORE of the questions then you ARE NOT a significant redevelopment and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. 3. Will the development create, replace, or add at least 5,000 square feet of impervious surfaces on an existing development or, be located within 200 feet of the Pacific Ocean and (1)create more than 2500 square feet of impermeable surface or (2) increases impermeable surface on property by more than 10%? / If you answered YES, you ARE a significant redevelopment, and you ARE subject to PRIORITY project requirements. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3 below. If you answered NO, you ARE NOT a significant redevelopment, and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. SECTION 3 Questionnaire Results: MY PROJECT MEETS PRIORITY REQUIREMENTS, MUST COMPLY WITH PRIORITY PROJECT STANDARDS AND MUST PREPARE A STORM WATER MANAGEMENT PLAN FOR SUBMITTAL AT TIME OF APPLICATION. MY PROJECT DOES NOT MEET PRIORITY REQUIREMENTS AND MUST ONLY COMPLY WITH STANDARD STORM WATER REQUIREMENTS. Applicant Information and Signature Box This Box for City Use Only City Concurrence: By: Project ID: SWMP Rev 6/4/08 This page intentionally left blank SWMP Rev 6/4/08 j.n. 03-127 2-23-09 Storm Water Management Plan Hagey Residence Jefferson Street Carlsbad, CA APN: 155-140-37 & -38 Pollutants of Concern The primary pollutants of concern, according to the attached table vNo. 2 for detached residential development, are sediments, nutrients, trash and debris, oxygen demanding substances, oil and grease, bacteria & viruses and pesticides. This project has been designed to maximize grass and landscaped areas for BMPs and to direct storm runoff from the roof to Jefferson Street right-of-way, to the maximum extents possible. Storm runoff from the roof down drains will be directed to landscaped areas where possible. The landscaped areas will have vegetated drainage swales to act as a filter to clean the water of pollutants. Energy dissipaters are to be used to minimize velocities prior to release into existing native vegetated swales. Numeric sizing will be included in construction plans and documents. Refer to grading plan and erosion control plan prepared by Sampo Engineering, Inc. dated November 04, 2008. This project proposes that the parking areas to be cleaned of trash and debris on a regular basis by the residents. The site discharges into the Buena Vista Lagoon Calwater Watershed 904.20. The Buena Vista Lagoon is impaired by Bacteria indicators, nutrients and sedimentation/siltation. Site Design BMP's • The project was designed to maximize the amount of storm water flow to the east to Jefferson Street public right-of-way in order to reduce flow and pollutants to the west, the front yard area, driveway, guest parking, and portions of the new roof will drain to Jefferson Street. • The project was designed to minimize the amount of grading and area of land disturbance, to maximize the amount of landscaped areas (i.e. pervious surface area) outside the building footprint, to the maximum extent practical. • The project was designed to minimize the use of impervious surfaces, such as decorative concrete, in the landscape areas. • The project proposed the use of landscaping that will minimize water usage and therefore minimize site runoff. Source Control BMP's • It is proposed that the project irrigation system employ a rain shutoff device to prevent irrigation during precipitation consistent with the Carlsbad Landscape Manual. • Post signs and prohibitive language and/or graphical icons, which prohibit illegal dumping at public access points along channels and creeks within the project area, trailheads and parks. BMP's Applicable to Individual Priority Project Categories • The proposed driveway shall have, to the extent practicable: a permeable surface (i.e. interlocking permeable pavers). • The proposed uncovered temporary guest parking shall be, to the extent practicable: a permeable surface (i.e. interlocking permeable pavers). • The proposed 3.5' wide grass-lined terrace swale is designed for treat 85™ percentile drainfall. • The proposed rip-rap energy dissipator is provided to slow the storm water velocity prior to discharging into the existing on-site vegetation. All proposed BMP's are private and shall be maintain by the property owner. 85th Percentile Flow and Volume determination Modified Rational Method-Effective for Watersheds < 1.0 mi2 Project: Hagey Residence 85th Percentile Rainfall= 0.62 inches (from County Isopluvial Map) Basin 1 Volume Based Volume =CPAwhere C=Coefficient for Development area only P=0.62 inches A=Area of development only in square feet C=0.84 see hydrology study V=CPA C=0.84 P=0.62in A=0.048 ac=2090 sf V=0.84x0.62x2090 (.84)(.62 in x 1ft) (.048 ac x 43560 fF)=91ft3 12 in 1 ac V=91 ft3 Flow Based Q=CIA C=Coefficient for Development area only 1=0.20 inch/hour A=Area of development only in acres Q=CIA C=0.84 1=0.20 A=0.048 ac 0=0.84x0.20x0.048 Q=0.008 cfs Basin 2 Volume Based Volume =CPAwhere C=Coefficient for Development area only P=0.62 inches A=Area of development only in square feet C=.35(876 SF) + .95(1521 SF) 2397 V=CPA C=0.73 P=0.62 A=0.055 ac=2397 sf V=0.73x0.62x2397 (.73)(.62 x L )(2397)=90 ft3 12 V=90 ft3 Flow Based Q=CIA C=Coefficient for Development area only 1=0.20 in/hour A=Area of development only in acres Q=CIA C=0.73 1=0.20 A=0.055 ac 0=0.73x0.20x0.055 Q=0.008 cfs Basin 3 Volume Based Volume =CPAwhere C=Coefficient for Development area only P=0.62 inches A=Area of development only in sqare feet C=.35(481 SF) + .95r975 1456 V=CPA C=0.75 P=0.62 A=0.034 ac=1456 sf V=0.75x0.62x0.034 (.75)(.62 x 1_ )(1456 sf)=56 ft3 12 V=56 ft3 Flow Based Q=CIA C=Coefficient for Development area only 1=0.20 in/hour A=Area of development only in acres Q=CIA C=0.75 1=0.20 A=0.034 ac 0=0.40x0.20x0.034 Q=0.005 cfs BEST ORIGINAL "505' ti» ;,iii. F f11 > VA v Treatment Control and Maintenance : 1. The subject property is located on the westerly side of Jefferson Street, just south of the intersection with Las Flores Drive, in the City of Carlsbad. The property is currently vacant; however there is evidence that a structure occupied the property in the past. The majority of the property descends from Jefferson Street to the west and northwest at an approximate grade of 25 percent. A small easterly portion of the site currently drains to Jefferson Street. 2. The project proposes to redevelop the property by constructing a new residence and attached garage. The project has been designed to minimize grading and construction of new impervious surfaces to the maximum extent possible. In addition, the intent of the design is to maximize the amount of storm water runoff to Jefferson Street and to minimize storm runoff to the west and northwest. The project also proposes a grass terraced swale and permeable driveway pavers for BMP purposes. Refer to the hydrology calculations. 3. The drainage concept maintains the existing drainage patterns, where approximately 90% of the run-off drains to the west end of property and 10% drains toward Jefferson Street. 4. The design provides for proper storm water energy dissipation measures by incorporating a rip-rap energy dissipator, which reduces the water velocity & associated energy prior to out-letting the storm water on the surface. This is an improvement over existing conditions, which provides no energy dissipator. 5. The slight increase of discharge (Q) of 0.16 CFS between pre & post condition is due to the new building, but no significant impact downstream is anticipated because of the limited amount of disturbance on the upper portion of the lot only. 6. Grass swales and BMP areas are privately maintained by the owner. 1034 Second Street * Encinitas, CA 92024 » phone: 760-436-0660 * fax: 760-436-0659 info@sampoengineering.com