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HomeMy WebLinkAboutCDP 06-25; HAGEY RESIDENCE CDP 06-25; PRELIMINARY STORM WATER MANAGEMENT PLAN; 2008-07-19Preliminary Storm Water Management plan Hagey Residence Jefferson Street Carlsbad, CA APN: 155-140-37 & -38 Prepared By: Sampo Engineering, Inc. 1034 Second Street Encinitas, CA 92024 RECEIVED JUL 2 0 m CITYOFCARLSBAD PLANNING DEPT j.n. 03-127 7-19-07 4/03/03 VI. RESOURCES & REFERENCES APPENDIX A STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST Complete Sections 1 and 2 of the following checklist to determine your project's permanent and construction storm water best management practices requirements. This form must be completed and submitted with your permit application. Section 1. Permanent Storm Water BMP Requirements: If any answers to Part A are answered "Yes," your project is subject to the "Priority Project Permanent Storm Water BMP Requirements," and "Standard Permanent Storm Water BMP Requirements" in Section III, "Permanent Storm Water BMP Selection Procedure" in the Storm Water Star)dards manual. If all answers to Part A are "No," and any answers to Part B are "Yes," your project is only subject to the "Standard Permanent Storm Water BMP Requirements". If every question in Part A and B is answered "No," your project is exempt from permanent storm water requirements. Part A: Determine Priority Project Permanent Storm Water BMP Requirements. Does the project meet the definition of one or more of the priority project categories?* Yes No 1. Detached residential development of 10 or more units / 2. Attached residential development of 10 or more units 3. Commercial development qreater than 100,000 square feet 4. Automotive repair shop X 5. Restaurant x_ 6. Steep hillside development greater than 5,000 square feet x_ X 7 Project discharging to receiving waters within Environmentally Sensitive Areas X x_ X 8. Parking lots greater than or equal to 5,000 ft'' or with at least 15 parking spaces, and potentially exposed to urban mnoff x_ X 9. Streets, roads, highways, and freeways which would create a new paved surface that is 5,000 square feet or qreater X * Refer to the definitions section in the Sform Water Standards for expanded definitions of the priority project categories. Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered priority projects. Parking lots, buildings and other structures associated with utility projects are priority projects if one or more of the criteria in Part A is met. If all answers to Part A are "No", continue to Part B. 4/03/03 Part B: Determine Standard Permanent Storm Water Requirements. Does the project propose: Yes No 1. New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks? 2. New pervious landscape areas and irrigation systems? 3. Permanent structures within 100 feet of any natural water body? 4. Trash storage areas? 5. Liquid or solid material loading and unloading areas? 6. Vehicle or equipment fueling, washing, or maintenance areas? 7. Require a General NPDES Permit for Storm Water Discharges Associated with Industrial Activities (Except construction)?* 8. Commercial or industrial waste handling or storage, excluding typical office or household waste? 9. Any grading or ground disturbance during construction? 10. Any new storm drains, or alteration to existing storm drains? Wa To find out if your project is required to obtain an individual General NPDES Permit for Storm Water Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web site at. www.swrcb.ca.gov/stormwtr/industrial.html _ Section 2. Construction Storm Water BMP Requirements: If the answer to question 1 of Part C is answered "Yes," your project is subject to Section IV "Construction Storm Water BMP Performance Standards," and must prepare a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question 1 Is "No," but the answer to any of the remaining questions Is "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No," your project is exempt from any construction storm water BMP requirements. If any of the answers to the questions in Part C are "Yes," complete the construction site prioritization in Part D, below. Part C: Determine Construction Phase Storm Water Requirements. Would the project meet any of these criteria during construction? 1. Is the project subject to California's statewide General NPDES Permit for Storm Water Discharges Associated With Construction Activities? — 2. Does the project propose grading or soil disturbance? Would storm water or urban runoff have the potential to contact any portion of the construction area, including washing and staging areas? Would the project use any construction materials that could negatively affect water quality if discharged from the site (such as, paints, solvents, concrete, and stucco)? : Yes No 2.^ 4/U3/U3 Part D: Determine Construction Site Priority In accordance with the Municipal Permit, each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low. This prioritization must be completed with this form, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of activities necessary to complete the construction and any other extenuating circumstances that may pose a threat to water quality. The City reserves the nght to adjust the priority of the projects both before and during construction. [Note: The construction priority does NOT change construction BMP requirements that apply to projects; all construction BMP requirements must be identified on a case-by-case basis The construction priority does affect the frequency of inspections that will be conducted by City staff. See Section IV.1 for more details on construction BMP requirements.] 13 A) High Priority 1) Projects where the site is 50 acres or more and grading will occur during the rainy season 2) Projects 5 acres or more. 3) Projects 5 acres or more within or directly adjacent to or discharging directly to a coastal lagoon or other receiving water within an environmentally sensitive area Projects, active or inactive, adjacent or tributary to sensitive water bodies • Bj Medium Priority 1) Capital Improvement Projects where grading occurs, however a Storm Water Pollution Prevention Plan (SWPPP) is not required under the State General Construction Permit (i.e., water and sewer replacement projects, intersection and street re-alignments, widening, comfort stations, etc.) 2) Permit projects in the public right-of-way where grading occurs, such as installation of sidewalk, substantial retaining walls, curb and gutter for an entire street frontage, etc., however SWPPPs are not required. 3) Permit projects on private property where grading permits are required, however, Notice Of Intents (NOIs) and SWPPPs are not required. • Cj Low Priority 1) Capital Projects where minimal to no grading occurs, such as signal light and loop installations, street light installations, etc. 2) Permit projects in the public right-of-way where minimal to no grading occurs, such as pedestrian ramps, driveway additions, small retaining walls, etc. 3) Permit projects on private property where grading permits are not required, such as small retaining walls, single-family homes, small tenant improvements, etc. 4/03/03 Ili. PERMANENT BEST MANAGEMENT PRACTICES SELECTION PROCEDURE When referred to this Section, by Step 2 of Section II, complete the analysis required for your project in the subsections of Section III.1 below. 1. IDENTIFY POLLUTANTS & CONDITIONS OF CONCERN A. Identify Pollutants from the Project Area Using Table 1, identify the project's anticipated pollutants. Pollutants associated with any hazardous material sites that have been remediated or are not threatened by the proposed project are not considered a pollutant of concern. Projects meeting the definition of more than one project category shall identify all general pollutant categories that apply. Table 2. Anticipated and Potential Pollutants Generated by Land Use Type. Project Categories Sediments Nutrients Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil& Grease Bacteria & Viruses Pesticides Detached Residential Development © 6) ® (S Attached Residential Development X X X Pd) P(2) Rd) X Commercial Development >100,000ft2 Pd) P(i) P(2) X P(5) X P(3) P(5) Automotive Repair X XCIP) X X Restaurants X X X X Hillside Development >5,000ft2 X X X X X X Parking Lots Pd) P(1) X X p{1) X P(1) Streets, Highways & Freeways X pd)X X X(4) X P(5) X X = anticipated P = potential (1) A potential pollutant if landscaping exists on-site. (2) A potential pollutant if the project includes uncovered parking areas. (3) A potential pollutant if land use involves food or animal waste products. (4) Including petroleum hydrocarbons. (5) Including solvents. 2002 CWA SECTION 303(d) LIST OF WATER QUALITY LIMITED SEGMENT ^/^^--'^^ SAN DIEGO REGIONAL WATER QUALITY CONTROL BOARD USEI'A: Julv 2003 R Agua Hedionda Creek E Agua Hedionda Lagoon R AJiso Creek E Aliso Creek (month) E Buena Vista Lagoon 90431000 90431000 90113000 90113000 90421000 Total Dissolved Solids Bacteria Indicators Sedimentation/Siltation Urban Runoff/Storm Sewers Unknown Nonpoint Source Unknown point source Nonpoint/Point Source NonpointflPoint Source Bacteria Indicators Urban RunofCStorm Sewers Unknown point source Nonpoint/Point Source Phosphorus Impairment located at lower 4 miles. Urban RunoC/Stonn Sewers Unknown Nonpoint Source Unknown point source Toxicity Bacteria Indicators Bacteria Indicators Urban RunofCStorm Sewers Unknown Nonpoint Source Unknown point source Nonpoint/Point Source Nonpoint/Point Source Low Low Low Medium Low Low Medium Low Nutrients Low Estimated size of impairment is 150 acres located in upper portion of lagoon. Nonpoint/Point Source Sedimentation/Siltation Medium Nonpoint/Point Source 7 Miles 6.8 Acres 6.8 Acres 19 Miles 19 Miles 19 Miles 0.29 Acres 202 Acres 202 Acres 202 Acres Page I of 16 Preliminary Storm Water Management Plan Hagey Residence Jefferson Street Carlsbad, CA APN: 155-140-37 & -38 Pollutants of Concern The primary pollutants of concem, according to the attached table no. 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 BMP's 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 drainage swales to act as a filter to clean the water of pollutants. Energy dissipater's are be used to minimize velocities prior to release into existing native bio-filters. Numeric sizing will be included in construction plans and documents. Refer to preliminary grading plan and erosion control plan prepared by Sampo Engineering, Inc. dated May 23, 2007. This project proposes that the parking areas to be cleaned of trash and debris on a regular basis by the residents. The site discharges in to 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 v^th 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). 85* Percentile Flow and Volume determination Modified Rational Method-Effective for Watersheds < 1.0 mP Project: Hagey Residence 85* 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 ft^)=91ft^ 12 in 1 ac V=91 ft^ 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 Q=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=.35f876 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 ft^ 12 V=90 ft^ 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 Q=0.73x0.20x0.055 Q=0.008 cfs Basin 3 Volume Based Volume =CP Awhere C=CoefiFicient for Development area only P=0.62 inches A=Area of development only in sqare feet C=.35(481 SF)+.95(975 SF) 1456 V=CPA C=0.75 P=0.62 A=0.034 ac=1456 sf V=0.75x0.62x0.034 (.75)(.62 x L )(1456 sf)=56 ft^ 12 V=56 ft' 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 Q=0.40x0.20x0.034 Q=0.005 cfs The permanent BMP design and layout for the above volume base or flow based 85**" percentile calculations will be finalized with the precise grading plan construction drawings. DRAINAGE STUDY CALCULATOR JN: 03-127 Hagen DATE: July 19,2007 INITIALS: PH DESCRIPTION: PROPOSED BASIN #2 SWALE Q=CIA C=Coefficient for residential, 1.0 DU/A or less A=Area of development only in square feet AREA = 2,397.00 SF = 0.055 AC. C = 0.73 Tc = 1.8f1.1-.25^(36W1/2) (1)'^(1/3) 9.18 1.00 9.18 hoo = 7.44(2.5)(9.18)'^(-.645) 4.45 IN/HR QlOO = (0.73)(4.45)(0.055 AC) 0.18 CFS 0.18cfs > .008 cfs required per flow based calculations for Basin 2 (see last page) •l-H V SSth Percentile Precipitation ^ Isopluvial Map Rainfall in Inches DRAFT mff^ 6/27/01 p-^^ V,. :xpmm ft V- 1^