The URL can be used to link to this page

Home My WebLink AboutCDP 01-41; Garfield Street Homes; Storm Water Quality; 2002-06-24<^ pro 1 STORM WATER MANAGEMENT PLAN GARFIELD STREET HOMES CDP 01 -41 Prepared by: Robert Sukup The Sea Bright Connpany 4322 Sea Bright Place Carlsbad, CA 92008 For Thomas Hurley and Lance Nowak 4751 Oceanside Blvd. - Suite D Oceanside, CA 92056 760-630-1540 June 24, 2002 TABLE OF CONTENTS INTRODUCTION 1.0 Project Description 1 1.1. Hydrolic Unit Contribution 1 1.2. Beneficial Use 1 1.2.1. Inland Surface Waters 2 1.2.2. Groundwater 2 2.0 CHARACTERIZATION OF PROJECT RUNOFF 2 2.1. Expected Discharges 2 2.2. Soil Characteristics 3 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY 3 3.1. Construction BMP's 3 3.2. Post construction BMP's 3 3.2.1.1 Appropriate Applications and Siting Constraints 3 4.0 OPERATIONS AND MAINTENANCE PROGRAM 4 5.0 FISCAL RESOURCES 4 ATTACHMENTS A. Project Map INTRODUCTION The Stomnwater Management Plan [SWMP] requirement is required under the County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance [section 67.817]. The purpose ofthis SWMP is to address the water quality impacts from the proposed improvements on the Garfield Street Properties project. Best Management Practices [BMP's] will be utilized to provide a long term solution to water quality. This SWMP is also intended to ensure the effectiveness of the BMP's through proper maintenance that is based on long term fiscal planning. The SWMP is subject to revisions as needed by the engineer. 1.0 Project Description The Garfield Street Homes project is located on a .14 acre vacant infill lot. The project will consist of two new apartments with attached garages and associated driveways. 1.1 Hydrologic Unit Contribution The Garfield Street Project is located in the Carlsbad Hydrologic Unit and more specifically in the Buena Vista Creek hydrolic area [unit 4.20 as designated in the San Diego Basin Plan]. The project area is characterized by an existing fully developed residential neighborhood of both single family and multiple family homes. This is one of only a few vacant parcels in the area. The proposed storm drain system will be surface flow through gravel/vegetated swales within the project with ultimate discharge onto an existing A.C. driveway. This driveway drains to existing City streets where the storm run off is picked up by the public storm drain system, with ultimate discharge to the near by ocean. The proposed project will not alter drainage patterns on the site or off site. The stormwater discharge points will not divert runoff from existing conditions. There will be an increase of runoff from the site of about .19 cfs for the 100 year storm. 1.2 Beneficial Uses The beneficial uses for the hydrolic unit that I foresee is listed below. This has been extracted from the water quality control plan for the San Diego Basin. Page 1 RECl - Contact Recreation: Includes uses of water for recreation activities involving body contact with water, where ingestion of water is reasonbly possible. The uses include, but are not limited to, swimming, wading, water skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs, [discharges to the near by ocean] 1.2.1 Inland Surface Waters Inland surface waters as applied to this project would be the possible recharge benefits to the groundwater. 1.2.2 Groundwater Groundwater beneficial uses for this project might potentially include agriculture, municipal or industrial. None of these beneficial uses will be impaired or diminish due to the construction and operation of the project. 2.0 CHARACTERIZATION OF PROJECT RUNOFF According to the California 1998 303d list published by the San Diego Regional Water Quality Control Board, there are no impaired water bodies that are associated with this project. 2.1 Expected discharges There is no sampling data available for the existing site condition. In addition, the project is not expected to generate significant amounts of non-visible pollutants. However, the following constituents are commonly found on similar developments and could affect water quality. 1. Sediment discharge due to construction activities and post construction areas left bare. 2. Nutrients from fertilizers. 3. Trash and debris deposited in drain inlets. 4. Hydrocarbons from paved areas. 5. Pesticides from landscaping and home use. Page 2 2.2 Soil Characteristics The project area consists within soil group D. Percolation rates are not available. 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY To address water quality for the project, BMP's will be implemented during construction and post construction. 3.1 Construction BMP's The construction BMP's that will be utilized during construction are as follows: 1. Silt Fence 2. Street Sweeping if needed. 3. Stockpile management 4. Solid waste management 5. Stabilized construction entrance/exit 6. Gravel bag berms 7. Concrete waste management 3.2 Post Construction BMP's The project is designed to have all drainage waters conveyed either through gravel drain swales or landscaped swales. Both "conveyance" structures are then designed to flow into a final rock absorption pit with exiting water conveyed through a 4" pipe with "T" ends in order to assimilate the initial sheet flow of the site. The potential pollutants identified earlier should be removed by filtration through the gravel and grass, sedimentation, infiltration through the soil, and final filtration/absorption through the rock absorption pit. 3.2.1 Appropriate Applications and Siting Constraints The gravel, vegetated swales and rock absorption pits are ideal "structures" to be utilized when flow velocities are not high enough to cause scour and where the climate allows for good plant growth. Both situations exist for this site. Page 3 4.0 OPERATION AND MAINTENANCE PROGRAM The operation and maintenance of the swales are as follows: 1. Verification that vegetation has grown in at the non gravel swales. 2. Removal of excessive weeds from the gravel swales if they do grow in. 3. Removal of sediment or trash debris from the swales. The swales should be visited a minimum of once a month or after each large storm during the first winter of existence. Any maintenance as described above needs to be done immediately. After the first full year of operation, no further formal review or maintenance of the swales should be necessary. 5.0 FISCAL RESOURCES Funds for maintenance will be paid by the owners of the apartments to the Landscape Maintenance Company. This Stormwater Management Plan has been prepared under the direction by the following Registered Civil Engineer: Robert 0. Sukup I _ 9/^/0 Sukup I ' Date Page 4 56E seweit. coo ^ ' T WITH •lyT^i 'IDE ^eARlOtb OU ORA\NAGE CUTLET ?rn5oc-rueE F.C. = PIW\SHEE COH0R6T6 PG. = FINISHED GIJADE • FimsHED •SUE.PAPS: INV- • INVEM ecgVATICN F-F. • PlUVSHED FLOOR B-)(\s^.iia&-VnL ITV PRE?Ag£P SY-. THE. «A BWSrtT COMPAMY 4322. •S6A -eRlliHT PLACe CARtSB.At) , CA ^EOOS O. •SUKUP 1!Cfe J630e exp -3-11-ot 'T4.0-7&0-0098 PLANNING CARLSBAD MUNIQPAL mTER DISTRICT DISTRICT ENQINEER R.C.E:-&3b'?a o(R>|3oJot D40MEER or «Df)K DEPARTMENT APPROVAL MH: / / REVISION DESCRIPTION OMR WPROVM. SHEET z 'AS BUILT* REVIEWEB BYi CITY OF GARLSBAD ll^i^^ ENGINEERING DEPARTMENT 4 GRlfilNG PUNS roS: CAWieUT^ STREET HOMtS APPROVED UJOiD B. HO?>*S OTY ENGINEER PE gtW EXPIRES B-3\-0S OATE 0*N BY: . CHKD BY:. RVWD BY: • PROJECT NO. CDP 01-41 DRAWING NO. Ih02-3A