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HomeMy WebLinkAbout3455; Costal Rail Trail, Reach 1; Storm Water Management Plan for the Coastal Rail Trail; 2004-05-01©0(4 110 ^L. STORM WATER MANAGEMENT PLAN FOR THE COASTAL RAIL TRAIL INTHE CITY OF CARLSBAD March 2004 TABLE OF CONTENTS INTRODUCTION 3 SITE DESCRIPTION 3 POTENTIAL POLLUTANTS AND SOURCES 3 BEST MANAGEMENT PRACTICES 4 TRAIL MAINTENANCE 4 PLAZA AND SIDEWALK CLEANING 4 LANDSCAPE MAINTENANCE 5 DRAINAGE SYSTEM MAINTENANCE 5 TRAINING 6 MONITORING, INSPECTION AND REPORTING 6 APPENDICES APPENDIX A - BMP'S FROM CALIFORNIA STORMWATER HANDBOOOK APPENDIX B - COASTAL RAIL TRAIL INSPECTION FORM APPENDIX C - HYDROLOGY CALCULATIONS Page 2 INTRODUCTION This report is being submitted to satisfy Condition 16 of the Coastal Development Permit CDP 03-31 for the project site as stated in Planning Commission Resolution 5569. The site is located within the North County Transit District (NCTD) Right-of-Way. The trail is twelve feet wide and will be constructed between Tamarack Avenue and Oak Avenue. This report identifies sources and types of the potential pollutants associated with operation, maintenance and use of the Coastal Rail Trail that may affect the quality of storm water discharge. Also included are recommended Best Management Practices (BMPs) to be implemented to reduce pollutants into the storm water discharge system. SITE DESCRIPTION The project location is a linear piece of land approximately forty feet wide starting at the eastern property line. The project is 3,658 feet long and 40 feet wide between Tamarack Avenue and Oak Avenue. The site acreage is 3.4 acres. The current site is dirt. There are no buildings within the project site. There are several underground utilities and one overhead phone line. Access to the underground utilities is throughout existing access holes. The site is currently accessed from a gate located at Tamarack Avenue. The Coastal Rail Trail will access the site from Oak, Chestnut and Tamarack. The Coastal Rail Trail is a multi-modal trail design for use by bicycles, pedestrians, skateboarders, roller bladers and pets on leash. The trail is twelve feet wide with a two-foot wide decomposed granite path on the east side and a three-foot wide drainage swale on the west side. The existing storm drain system will pick up storm drain flows at five locations. Four of those locations have inlets on each side of the trail. Storm water flows will be collected in vegetated swales along the two project boundaries on the east and west and conveyed into the existing Type B inlets. Storm water form the trail will sheet flow into a stamped concrete channel that will be conveyed to the existing drainage system as well. The site currently sheet flows into four existing Type B inlets. The site currently does not have landscaping. POTENTIAL POLLUTANTS AND SOURCES The following is a list of the potential pollutants of concern that may be produced from the subject site: Litter Small amounts of oil and grease from maintenance vehicles Sediment Pesticides Herbicide Page 3 BEST MANAGEMENT PRACTICES The Coastal Rail Trail shall implement the following BMPs from the California Storm Water BMP Handbook Municipal Facilities: SC-70, Road and Street Maintenance SC-71, Plaza and Sidewalk Cleaning SC-73, Landscape Maintenance SC-74, Drainage Maintenance TRAIL MAINTENANCE: Street Sweep Hardscape Areas: The trail drains into a stamped concrete swale. The trail and swale will be swept bi-weekly and litter pickup will occur daily. Litter control and regular sweeping will reduce pollutants conveyed into the drainage system. Sweeping will be performed when the site is dry to maximize benefits. Sweeping shall not use kick brooms. Sweepers shall be operated per manufacturers requirements. Trail Coordinator will maintain a log of sweeping frequency and amount of waste collected. Waste collected during sweeping will be properly disposed of. Graffiti Removal: Graffiti removal shall be scheduled as soon as graffiti is reported. It is preferable to use dry methods to remove graffiti. If wet methods are used, the area must be swept or vacuumed to remove wet material. Absorbent may be used and properly disposed of. If pressure washing is used without cleaning agents, direct to landscape areas. If a cleansing agent is used, vacuum/pump wash water to sanitary sewer. Litter Control: Daily litter removal is required. PLAZA AND SIDEWALK CLEANING Surface Cleaning: Surface cleaning shall occur in dry weather and use dry methods whenever practical. Graffiti Removal and Litter Control: Graffiti removal and litter control shall be consistent with Trail Maintenance. Page 4 LANDSCAPE MAINTENANCE: Landscape Maintenance: Landscape maintenance activities will include removal of vegetation due to pruning, weeding or plant replacement. Fertilizer applications shall be properly timed. This project has a Green Waste management program. It is anticipated that some reuse of green waste can occur on the project. Mulch will be installed initially and maintained throughout the project. Pesticides and herbicides will be used only when the site is dry and not near a storm drain facility. Irrigation Maintenance: Regular inspection of the irrigation system shall ensure that sprinklers are operating as designed and that over spray is not getting onto fences and paved areas. If leaks are detected, the irrigation valve shall be turned off until the leak is repaired. Pesticide Application: Pesticide use shall be limited to infestations and should be applied at the appropriate time to maximize the use of the pesticide. Pesticide applications must be done with properly operating and maintained equipment and under the supervision of a California qualified pesticide applicator. Spill Management: Spill materials are to be readily available when maintenance is being performed. DRAINAGE SYSTEM MAINTENANCE: Swales: This project has both concrete lined and vegetated lined swales. The concrete lined swales are addressed with street sweeping and litter control. The site drains into a series of existing inlet structures that drain into an existing storm drain. Vegetated Swales in Landscape Areas: Storm water will be discharged from the site directly into the storm drain system. The project includes two vegetated swales to carry runoff from the landscaped areas to the existing storm drain system. Prior to the construction of this project, runoff flowed directly off the railroad right of way into the storm drain system. Routine monitoring should be conducted to ensure no obstructions are in the vegetated swales. Obstructions should be immediately removed and disposed of. Monitoring for erosion should be conducted at these visits and corrective measures implemented to prevent erosion. Monitoring for standing water shall occur year around. Maintenance activities need to eliminate standing water. Page 5 Post storm event monitoring shall ensure swales are flowing properly. TRAINING All training will be tracked in a training log. Employees performing landscape maintenance shall be trained in proper use of pesticides, herbicide and fertilizers. Employees will also be trained that over-the- counter pesticide are not to be used. Employees are to be trained to monitor irrigation for proper water techniques and proper adjustment to system to maintain proper watering schedule. Only properly trained individuals are allowed to handle hazardous waste. Training of all employees (and eventually trail users) in addition to maintenance crews to recognize and report illegal dumping. Train employees to educate the public proper and consistent methods for disposal and to recognize non-storm discharges. Train maintenance crews' proper use and maintenance of equipment. MONITORING, INSPECTiON AND REPORTING The City of Carlsbad will maintain the BMPs implemented in the project throughout the life of the project in conformance with the City's Post Construction BMP guidelines. The City shall monitor, inspect and report occurrences of the BMP plan. The Coastal Rail Trail Coordinator will maintain all records and have available for inspection by appropriate City Staff all compliance documents for the BMPs. Maintenance and monitoring schedules and forms are included in the Coastal Rail Trail Management Plan. Page 6 APPENDIX A BMP'S FROM CALIFORNIA STORMWATER BMP HANDBOOK SC-70 ROAD AND STREET MAINTENANCE SC-71 PUKZAAND SIDEWALK CLEAINING SC-73 LANDSCAPE MAINTENANCE SC-74 DRAINAGE SYSTEM MAINTENANCE Road and Street Maintenance SC-70 Description Streets, roads, and highways are significant sources of pollutants in stormwater discharges, and operation and maintenance (O&M) practices, if not conducted properly, can contribute to the problem. Stormwater pollution from roadway and bridge maintenance should be addressed on a site-specific basis. Use of the procedures outlined below, that address street sweeping and repair, bridge and structure maintenance, and unpaved roads will reduce pollutants in stormwater. Approach Pollution Prevention m Use the least toxic materials available (e.g. water based paints, gels or sprays for graffiti removal) • Recycle paint and other materials whenever possible. • Enlist the help of citizens to keep yard waste, used oil, and other wastes out of the gutter. Suggested Protocols Street Sweeping and Cleaning • Maintain a consistent sweeping schedule. Provide minimum monthly sweeping of curbed streets. • Perform street cleaning during dry weather if possible. Objectives Cover Contain Educate Reduce/Minimize Product Substitution Targeted Constituents Sediment / Nutrients Trash •/ Metals •/ Bacteria Oil and Grease V Organics ^ Oxygen Demanding V I California Stormwater Quality Association January 2003 California Stormwater BMP Handbool< Municipal www.cabmphandbooks.com 1 of 9 SC-70 Road and Street Maintenance • Avoid wet cleaning or flushing of street, and utiUze dry methods where possible. • Consider increasing sweeping frequency based on factors such as traffic volume, land use, field observations of sediment and trash accumulation, proximity to water courses, etc. For example: - Increase the sweeping frequency for streets with high pollutant loadings, especially in high traffic and industrial areas. - Increase the sweeping frequency just before the wet season to remove sediments accumulated during the summer. - Increase the sweeping firequency for streets in special problem areas such as special events, high litter or erosion zones. • Maintain cleaning equipment in good working condition and purchase replacement equipment as needed. Old sweepers should be replaced with new technologically advanced sweepers (preferably regenerative air sweepers) that maximize pollutant removal. • Operate sweepers at manufacturer requested optimal speed levels to increase effectiveness. • To increase sweeping effectiveness consider the following: - Institute a parking policy to restrict parking in problematic areas during periods of street sweeping. - Post permanent street sweeping signs in problematic areas; use temporary signs if installation of permanent signs is not possible. - Develop and distribute flyers notifying residents of street sweeping schedules. • Regularly inspect vehicles and equipment for leaks, and repair immediately. • If available use vacuum or regenerative air sweepers in the high sediment and trash areas (typically industrial/commercial). • Keep accurate logs of the number of curb-miles swept and the amount of waste collected. • Dispose of street sweeping debris and dirt at a landfill. • Do not store swept material along the side of the street or near a storm drain inlet. • Keep debris storage to a minimum during the wet season or make sure debris piles are contained (e.g. by berming the area) or covered (e.g. with tarps or permanent covers). Street Repair and Maintenance Pavement marking u Schedule pavement marking activities for dry weather. 2 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Road and Street Maintenance SC-70 • Develop paint handling procedures for proper use, storage, and disposal of paints. • Transfer and load paint and hot thermoplastic away from storm drain inlets. • Provide drop cloths and drip pans in paint mixing areas. • Properly maintain application equipment. • Street sweep thermoplastic grindings. Yellow thermoplastic grindings may require special handling as they may contain lead. • Paints containing lead or tributyltin are considered a hazardous waste and must be disposed of properly. • Use water based paints whenever possible. If using water based paints, clean the application equipment in a sink that is connected to the sanitary sewer. • Properly store leftover paints if they are to be kept for the next job, or dispose of properly. Concrete instaUation and repair m Schedule asphalt and concrete activities for dry weather. • Take measures to protect any nearby storm drain inlets and adjacent watercourses, prior to breaking up asphalt or concrete (e.g. place san bags around inlets or work areas). • Limit the amount of fresh concrete or cement mortar mixed, mix only what is needed for the job. • Store concrete materials under cover, away from drainage areas. Secure bags of cement after they are open. Be sure to keep wind-blown cement powder away from streets, gutters, storm drains, rainfall, and mnoff. • Return leftover materials to the transit mixer. Dispose of small amounts of hardened excess concrete, grout, and mortar in the trash. • Do not wash sweepings from exposed aggregate concrete into the street or storm drain. Collect and return sweepings to aggregate base stockpile, or dispose in the trash. • When making saw cuts in pavement, use as littie water as possible and perform during dry weather. Cover each storm drain inlet completely with filter fabric or plastic during the sawing operation and contain the slurry by placing straw bales, sandbags, or gravel dams around the inlets. After the liquid drains or evaporates, shovel or vacuum the slurry residue from the pavement or gutter and remove from site. Alternatively, a small onsite vacuum may be used to pick up the slurry as this will prohibit slurry from reaching storm drain inlets. • Wash concrete trucks off site or in designated areas on site designed to preclude discharge of wash water to drainage system. January 2003 Califomia Stormwater BMP Handbook 3 of 9 Municipal www.cabmphandbooks.com SC-70 Road and Street Maintenance Patching, resurfacing, and surface sealing • Schedule patching, resurfacing and surface sealing for dry weather. • Stockpile materials away from streets, gutter areas, storm drain inlets or watercourses. During wet weather, cover stockpiles with plastic tarps or berm around them if necessary to prevent transport of materials in runoff. • Pre-heat, transfer or load hot bituminous material away from drainage systems or watercourses. • Where applicable, cover and seal nearby storm drain inlets (with waterproof material or mesh) and maintenance holes before applying seal coat, slurry seal, etc. Leave covers in place until job is complete and until all water from emulsified oil sealants has drained or evaporated. Clean any debris from covered maintenance holes and storm drain inlets when thejob is complete. • Prevent excess material from exposed aggregate concrete or similar treatments from entering streets or storm drain inlets. Designate an area for clean up and proper disposal of excess materials. • Use only as much water as necessary for dust control, to avoid ranoff. • Sweep, never hose down streets to clean up tracked dirt. Use a street sweeper or vacuum track. Do not dump vacuumed liquid in storm drains. • Catch drips from paving equipment that is not in use with pans or absorbent material placed under the machines. Dispose of collected material and absorbents properly. Equipment cleaning maintenance and storage u Inspect equipment daily and repair any leaks. Place drip pans or absorbent materials under heavy equipment when not in use. • Perform major equipment repairs at the corporation yard, when practical. • If refueling or repairing vehicles and equipment must be done onsite, use a location away from storm drain inlets and watercourses. • Clean equipment including sprayers, sprayer paint supply lines, patch and paving equipment, and mud jacking equipment at the end of each day. Clean in a sink or other area (e.g. vehicle wash area) that is connected to the sanitary sewer. Bridge and Structure Maintenance Paint and Paint Removal • Transport paint and materials to and from job sites in containers with secure lids and tied down to the transport vehicle. • Do not transfer or load paint near storm drain inlets or watercourses. 4 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Road and Street Maintenance SC-70 • Test and inspect spray equipment prior to starting to paint. Tighten all hoses and connections and do not overfill paint container. • Plug nearby storm drain inlets prior to starting painting where there is significant risk of a spill reaching storm drains. Remove plugs when job is completed. • If sand blasting is used to remove paint, cover nearby storm drain inlets prior to starting work. • Perform work on a maintenance traveler or platform, or use suspended netting or tarps to capture paint, rast, paint removing agents, or other materials, to prevent discharge of materials to surface waters if the bridge crosses a watercourse. If sanding, use a sander with a vacuum filter bag. • Capture all clean-up water, and dispose of properly. • Recycle paint when possible (e.g. paint may be used for graffiti removal activities). Dispose of unused paint at an appropriate household hazardous waste facility. Graffiti Removal m Schedule graffiti removal activities for dry weather. • Protect nearby storm drain inlets prior to removing graffiti from walls, signs, sidewalks, or other stractures needing graffiti abatement. Clean up afterwards by sweeping or vacuuming thoroughly, and/or by using absorbent and properly disposing ofthe absorbent. • When graffiti is removed by painting over, implement the procedures under Painting and Paint Removal above. • Direct mnoff from sand blasting and high pressure washing (with no cleaning agents) into a landscaped or dirt area. If such an area is not available, filter runoff through an appropriate filtering device (e.g. filter fabric) to keep sand, particles, and debris out of storm drains. • If a graffiti abatement method generates wash water containing a cleaning compound (such as high pressure washing with a cleaning compound), plug nearby storm drains and vacuum/pump wash water to the sanitary sewer. • Consider using a waterless and non-toxic chemical cleaning method for graffiti removal (e.g. gels or spray compounds). Repair Work • Prevent concrete, steel, wood, metal parts, tools, or other work materials from entering storm drains or watercourses. • Thoroughly clean up thejob site when the repair work is completed. • When cleaning guardrails or fences follow the appropriate surface cleaning methods (depending on the type of surface) outiined in SC-71 Plaza & Sidewalk Cleaning fact sheet. January 2003 California Stormwater BMP Handbook 5 of 9 Municipal www.cabmphandbooks.com SC-70 Road and Street Maintenance • If painting is conducted, follow the painting and paint removal procedures above. • If graffiti removal is conducted, follow the graffiti removal procedures above. • If construction takes place, see the Construction Activity BMP Handbook. • Recycle materials whenever possible. Unpaved Roads and Trails m Stabilize exposed soil areas to prevent soil from eroding during rain events. This is particularly important on steep slopes. • For roadside areas with exposed soils, the most cost-effective choice is to vegetate the area, preferably with a mulch or binder that will hold the soils in place while the vegetation is establishing. Native vegetation should be used if possible. • If vegetation cannot be established immediately, apply temporary erosion control mats/blankets; a comma straw, or gravel as appropriate. • If sediment is already eroded and mobilized in roadside areas, temporary controls should be installed. These may include: sediment control fences, fabric-covered triangular dikes, gravel-filled burlap bags, biobags, or hay bales staked in place. Non-Stormwater Discharges Field crews should be aware of non-stormwater discharges as part of their ongoing street maintenance efforts. • Refer to SC-io Non-Stormwater Discharges • Identify location, time and estimated quantity of discharges. • Notify appropriate personnel. Training m Train employees regarding proper street sweeping operation and street repair and maintenance. • Instruct employees and subcontractors to ensure that measures to reduce the stormwater impacts of roadway/bridge maintenance are being followed. • Require engineering staff and/or consulting A/E firms to address stormwater quality in new bridge designs or existing bridge retrofits. • Use a training log or similar method to document training. • Train employees on proper spill containment and clean up, and in identifying non- stormwater discharges. 6 of 9 California Stormwater BMP Handbook January 2003 Munidpal www.cabmphandbooks.com Road and Street Maintenance SC-70 Spill Response and Prevention m Refer to SC-ii, Spill Prevention, Control & Cleanup. • Keep your Spill Prevention Control and countermeasure (SPCC) plan up-to-date, and implement accordingly. • Have spill cleanup materials readily available and in a known location. • Cleanup spills immediately and use dry methods if possible. • Properly dispose of spill cleanup material. Other ConsfdcrorioTis • Densely populated areas or heavily used streets may require parking regulations to clear streets for cleaning. • No currently available conventional sweeper is effective at removing oil and grease. Mechanical sweepers are not effective at removing finer sediments. • Limitations may arise in the location of new bridges. The availability and cost of land and other economic and political factors may dictate where the placement of a new bridge will occur. Better design of the bridge to control runoff is required if it is being placed near sensitive waters. Requirements Costs • The maintenance of local roads and bridges is already a consideration of most community public works or transportation departments. Therefore, the cost of pollutant reducing management practices will involve the training and equipment required to implement these new practices. • The largest expenditures for street sweeping programs are in staffing and equipment. The capital cost for a conventional street sweeper is between $60,000 and $120,000. Newer technologies might have prices approaching $180,000. The average useful life of a conventional sweeper is about four years, and programs must budget for equipment replacement. Sweeping frequencies will determine equipment life, so programs that sweep more often should expect to have a higher cost of replacement. • A street sweeping program may require the following. - Sweeper operators, maintenance, supervisory, and administrative personnel are required. - Traffic control officers may be required to enforce parking restrictions. - Skillful design of cleaning routes is required for program to be productive. - Arrangements must be made for disposal of collected wastes. January 2003 California Stormwater BMP Handbook 7 of 9 Municipal www.cabmphandbooks.com SC-70 Road and Street Maintenance • If investing in newer technologies, training for operators must be included in operation and maintenance budgets. Costs for public education are small, and mostly deal with the need to obey parking restrictions and litter control. Parking tickets are an effective reminder to obey parking rules, as well as being a source of revenue. Maintenance • Not applicable Supplemental Information Further Detail ofthe BMP Street sweeping There are advantages and disadvantages to the two common types of sweepers. The best choice depends on your specific conditions. Many communities find it useful to have a compliment of both types in their fleet. Mechanical Broom Sweepers - More effective at picking up large debris and cleaning wet streets. Less costly to purchase and operate. Create more airborne dust. Vacuum Sweepers - More effective at removing fine particles and associated heavy metals. Ineffective at cleaning wet streets. Noisier than mechanical broom sweepers which may restrict areas or times of operation. May require an advance vehicle to remove large debris. Street Flushers - Not affected by biggest interference to cleaning, parked cars. May remove finer sediments, moving them toward the gutter and stormwater inlets. For this reason, flushing fell out of favor and is now used primarily after sweeping. Flushing may be effective for combined sewer systems. Presentiy street flushing is not allowed under most NPDES permits. Cross-Media Transfer of Pollutants The Califomia Air Resources Board (ARB) has established state ambient air quality standards including a standard for respirable particulate matter Gess than or equal to lo microns in diameter, symbolized as PMio). In the effort to sweep up finer sediments to remove attached heavy metals, municipalities should be aware that fine dust, that cannot be captured by the sweeping equipment and becomes airborne, could lead to issues of worker and public safety. Bridges Bridges that carry vehicular traffic generate some of the more direct discharges of runoff to surface waters. Bridge scupper drains cause a direct discharge of stormwater into receiving waters and have been shown to carry relatively high concentrations of pollutants. Bridge maintenance also generates wastes that may be either directiy deposited to the water below or carried to the receiving water by stormwater. The following steps will help reduce the stormwater impacts of bridge maintenance: • Site new bridges so that significant adverse impacts to wetiands, sensitive areas, critical habitat, and riparian vegetation are minimized. 8 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Road and Street Maintenance SC-70 • Design new bridges to avoid the use of scupper drains and route runoff to land for treatment control. Existing scupper drains should be cleaned on a regular basis to avoid sediment/debris accumulation. • Reduce the discharge of pollutants to surface waters during maintenance by using suspended traps, vacuums, or booms in the water to capture paint, rust, and paint removing agents. Many of these wastes may be hazardous. Properly dispose of this waste by referring to CA21 (Hazardous Waste Management) in the Construction Handbook. • Train employees and subcontractors to reduce the discharge of wastes during bridge maintenance. De-icing m Do not over-apply deicing salt and sand, and routinely calibrate spreaders. • Near reservoirs, restrict the application of deicing salt and redirect any runoff away from reservoirs. • Consider using alternative deicing agents Gess toxic, biodegradable, etc.). References and Resources Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipalities. Prepared by City of Monterey, City of Santa Cruz, Califomia Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Govemments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. Orange County Stormwater Program http://www.ocwatersheds.com/stormwater/swp introduction.asp Oregon Association of Clean Water Agencies. Oregon Municipal Stormwater Toolbox for Maintenance Practices. June 1998. Santa Clara Valley Urban Runoff Pollution Prevention Program. 1997 Urban Runoff Management Plan. September 1997, updated October 2000. Santa Clara Valley Urban Runoff Pollution Prevention Program. 2001. Fresh Concrete and Mortar Application Best Management Practices for the Constmction Industry. June. Santa Clara Valley Urban Runoff Pollution Prevention Program. 2001. Roadwork and Paving Best Management Practices for the Constmction Industry. June. United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Roadway and Bridge Maintenance. On-line http://www.epa.gov/npdes/menuofbmps/poll if^.htm January 2003 California Stormwater BMP Handbook 9 of 9 Municipal www.cabmphandbooks.com Plaza and Sidewalk Cleaning SC-71 Description Pollutants on sidewalks and other pedestrian traffic areas and plazas are typically due to littering and vehicle use. This fact sheet describes good housekeeping practices that can be incorporated into the municipalit>''s existing cleaning and maintenance program. Approach PoUution Prevention m Use dry cleaning methods whenever practical for surface cleaning activities. • Use the least toxic materials available (e.g. water based paints, gels or sprays for graffiti removal). Suggested Protocols Surface Cleaning m Regularly broom (dry) sweep sidewalk, plaza and parking lot areas to minimize cleaning with water. • Dry cleanup first (sweep, collect, and dispose of debris and trash) when cleaning sidewalks or plazas, then wash with or without soap. • Block the storm drain or contain runoff when cleaning with water. Discharge wash water to landscaping or collect water and pump to a tank or discharge to sanitary sewer if allowed. (Permission maybe required from local sanitation district.) Objectives Cover Contain Educate Reduce/Minimize Product Substitution Targeted Constituents Sediment Nutrients Trash Metals Bacteria Oil and Grease Organics Oxygen Demanding S Q A i California Stormwater Quality Association January 2003 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com 1 of 5 SC-71 Plaza and Sidewalk Cleaning • Block the storm drain or contain mnoff when washing parking areas, driveways or drive- throughs. Use absorbents to pick up oil; then dry sweep. Clean with or without soap. Collect water and pump to a tank or discharge to sanitary sewer if allowed. Street Repair and Maintenance. Graffiti Removal m Avoid graffiti abatement activities during rain events. • Implement the procedures under Painting and Paint Removal in SC-70 Roads, Streets, and Highway Operation and Maintenance fact sheet when graffiti is removed by painting over. • Direct mnoff from sand blasting and high pressure washing (with no cleaning agents) into a dirt or landscaped area after treating with an appropriate filtering device. • Plug nearby storm drain inlets and vacuum/pump wash water to the sanitary sewer if authorized to do so if a graffiti abatement method generates wash water containing a cleaning compound (such as high pressure washing with a cleaning compound). Ensure that a non-hazardous cleaning compound is used or dispose as hazardous waste, as appropriate. Surface Removal and Repair • Schedule surface removal activities for dry weather if possible. • Avoid creating excess dust when breaking asphalt or concrete. • Take measures to protect nearby storm drain inlets prior to breaking up asphalt or concrete (e.g. place hay bales or sand bags around inlets). Clean afterwards by sweeping up as much material as possible. • Designate an area for clean up and proper disposal of excess materials. • Remove and recycle as much of the broken pavement as possible to avoid contact with rainfall and stormwater mnoff. • When making saw cuts in pavement, use as little water as possible. Cover each storm drain inlet completely with filter fabric during the sawing operation and contain the slurry by placing straw bales, sandbags, or gravel dams around the inlets. After the liquid drains or evaporates, shovel or vacuum the slurry residue from the pavement or gutter and remove from site. • Always dry sweep first to clean up tracked dirt. Use a street sweeper or vacuum tmck. Do not dump vacuumed liquid in storm drains. Once dry sweeping is complete, the area may be hosed down if needed. Wash water should be directed to landscaping or collected and pumped to the sanitary sewer if allowed. Concrete InstaUation and Repair m Schedule asphalt and concrete activities for dry weather. 2 of 5 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Plaza and Sidewalk Cleaning SC-71 • Take measures to protect any nearby storm drain inlets and adjacent watercourses, prior to breaking up asphalt or concrete (e.g. place san bags around inlets or work areas). • Limit the amount of fresh concrete or cement mortar mixed, mix only what is needed for the job. • Store concrete materials under cover, away from drainage areas. Secure bags of cement after they are open. Be sure to keep wind-blown cement powder away from streets, gutters, storm drains, rainfall, and mnoff. • Return leftover materials to the transit mixer. Dispose of small amounts of hardened excess concrete, grout, and mortar in the trash. • Do not wash sweepings from exposed aggregate concrete into the street or storm drain. Collect and return sweepings to aggregate base stockpile, or dispose in the trash. • Protect applications of fresh concrete from rainfall and mnoff until the material has dried. • Do not allow excess concrete to be dumped onsite, except in designated areas. • Wash concrete tmcks off site or in designated areas on site designed to preclude discharge of wash water to drainage system. ControUing Litter • Post "No Littering" signs and enforce anti-litter laws. • Provide litter receptacles in busy, high pedestrian traffic areas of the community, at recreational facilities, and at community events. • Cover litter receptacles and clean out frequently to prevent leaking/spillage or overflow. • Clean parking lots on a regular basis with a street sweeper. Training m Provide regular training to field employees and/or contractors regarding surface cleaning and proper operation of equipment. • Train employee and contractors in proper techniques for spill containment and cleanup. • Use a training log or similar method to document training. SpiU Response and Prevention u Refer to SC-ii, Spill Prevention, Control & Cleanup. • Have spill cleanup materials readily available and in a known location. • Cleanup spills immediately and use dry methods if possible. • Properly dispose of spill cleanup material. January 2003 California Stormwater BMP Handbook 3 of 5 Municipal www.cabmphandbooks.com SC-71 Plaza and Sidewalk Cleaning Other Considerations m Limitations related to sweeping activities at large parking facilities may include current sweeper technology to remove oil and grease. • Surface cleaning activities that require discharges to the local sewering agency will require coordination with the agency. • Arrangements for disposal of the swept material collected must be made, as well as accurate tracking of the areas swept and the frequency of sweeping. Requirements Costs m The largest expenditures for sweeping and cleaning of sidewalks, plazas, and parking lots are in staffing and equipment. Sweeping of these areas should be incorporated into street sweeping programs to reduce costs. Maintenance Not applicable Supplemental Information Further Detail ofthe BMP Community education, such as informing residents about their options for recycling and waste disposal, as well as the consequences of littering, can instill a sense of citizen responsibUity and potentially reduce the amount of maintenance required by the municipality. Additional BMPs that should be considered for parking lot areas include: • Allow sheet mnoff to flow into biofilters (vegetated strip and swale) and infiltration devices. • Utilize sand filters or oleophilic collectors for oily waste in low concentrations. • Arrange rooftop drains to prevent drainage directiy onto paved surfaces. • Design lot to include semi-permeable hardscape. • Stmctural BMPs such as storm drain inlet filters can be very effective in reducing the amount of pollutants discharged from parking facilities during periods of rain. References and Resources Bay Area Stormwater Management Agencies Association (BASMAA). 1996. Pollution From Surface Cleaning Folder http://www.basmaa.org Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipalities. Prepared by City of Monterey, City of Santa Cmz, California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. 4 of 5 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Plaza and Sidewalk Cleaning SC-71 Oregon Association of Clean Water Agencies. Oregon Municipal Stormwater Toolbox for Maintenance Practices. June 1998. Orange County Stormwater Program http://www.ocwatersheds.com/stormwater/swp introduction.asp Santa Clara Valley Urban Runoff Pollution Prevention Program. 1997 Urban Runoff Management Plan. September 1997, updated October 2000. Santa Clara Valley Urban Runoff Pollution Prevention Program. Maintenance Best Management Practices for the Constmction Industry. Brochures: Landscaping, Gardening, and Pool; Roadwork and Paving; and Fresh Concrete and Mortar Application. June 2001. San Diego Stonnwater Co-permittees Jurisdictional Urban Runoff Management Plan. 2001. Municipal Activities Model Program Guidance. November. January 2003 Califomia Stormwater BMP Handbook 5 of 5 Municipal www.cabmphandbooks.com Landscape Maintenance SC-73 Objectives Contain Educate Reduce/Minimize Product Substitution Targeted Constituents Description Landscape maintenance activities include vegetation removal; herbicide and insecticide application; fertilizer application; watering; and other gardening and lawn care practices. Vegetation control typically involves a combination of chemical (herbicide) application and mechanical methods. All of these maintenance practices have the potential to contribute pollutants to tho storm drain system. The major objectives of this BMP are to minimize the discharge of pesticides, herbicides and fertilizers to the storm drain system and receiving waters; prevent the disposal of landscape waste into the storm drain system by collecting and properly disposing of clippings and cuttings, and educating employees and the public. Approach PoUution Prevention m Implement an integrated pest management (IPM) program. IPM is a sustainable approach to managing pests by combining biological, cultural, physical, and chemical tools. • Choose low water using flowers, trees, shrubs, and groundcover. • Consider alternative landscaping techniques such as naturescaping and xeriscaping. • Conduct appropriate maintenance (i.e. properly timed fertilizing, weeding, pest control, and pruning) to help preserve the landscapes water efficiency. Sediment Nutrients Trash Metals Bacteria Oil and Grease Organics Oxygen Demanding S Q A C.I lif ornia Stormwater Quality Association January 2003 California Stormwater BMP Handbook Municipal www.cabmphandbooics.com 1 of 6 SC-73 Landscape Maintenance • Consider grass cycling (grass cycling is the natural recychng of grass by leaving the clippings on the lawn when mowing. Grass clippings decompose quickly and release valuable nutrients back into the lawn). Suggested Protocols Mowing, Trimming, and Weeding u Whenever possible use mechanical methods of vegetation removal (e.g movring with tractor- type or push mowers, hand cutting with gas or electric powered weed trimmers) rather than applying herbicides. Use hand weeding where practical. • Avoid loosening the soil when conducting mechanical or manual weed control, this could lead to erosion. Use mulch or other erosion control measures when soils are exposed. • Performing mowing at optimal times. Movring should not be performed if significant rain events are predicted. • Mulching mowers may be recommended for certain flat areas. Other techniques may be employed to minimize mowing such as selective vegetative planting using low maintenance grasses and shmbs. • Collect lawn and garden clippings, pmning waste, tree trimmings, and weeds. Chip if necessary, and compost or dispose of at a landfill (see waste management section of this fact sheet). • Place temporarily stockpfled material away from watercourses, and berm or cover stockpiles to prevent material releases to storm drains. Planfing • Determine existing native vegetation features Gocation, species, size, function, importance) and consider the feasibility of protecting them. Consider elements such as their effect on drainage and erosion, hardiness, maintenance requirements, and possible conflicts between preserving vegetation and the resulting maintenance needs. • Retain and/or plant selected native vegetation whose features are determined to be beneficial, where feasible. Native vegetation usually requires less maintenance (e.g., irrigation, fertilizer) than planting new vegetation. • Consider using low water use groundcovers when planting or replanting. Waste Management m Compost leaves, sticks, or other collected vegetation or dispose of at a permitted landfill. Do not dispose of collected vegetation into waterways or storm drainage systems. • Place temporarily stockpfled material away from watercourses and storm drain inlets, and berm or cover stockpUes to prevent material releases to the storm drain system. • Reduce the use of high nitrogen fertUizers that produce excess growth requiring more frequent mowing or trimming. 2 of 6 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Landscape Maintenance SC-73 • Avoid landscape wastes in and around storm drain inlets by either using bagging equipment or by manually picking up the material. Irrigation • Where practical, use automatic timers to minimize mnoff. • Use popup sprinkler heads in areas with a lot of activity or where there is a chance the pipes may be broken. Consider the use of mechanisms that reduce water flow to sprinkler heads if broken. • Ensure that there is no mnoff from the landscaped area(s) if re-claimed water is used for irrigation. • If baUing of muddy water is required (e.g. when repairing a water line leak), do not put it in the storm drain; pour over landscaped areas. • Irrigate slowly or pulse irrigate to prevent mnoff and then only irrigate as much as is needed. • Apply water at rates that do not exceed the infiltration rate of the soU. Fertilizer and Pesticide Management m UtUize a comprehensive management system that incorporates integrated pest management (IPM) techniques. There are many methods and types of IPM, including the following: - Mulching can be used to prevent weeds where turf is absent, fencing instaUed to keep rodents out, and netting used to keep birds and insects away from leaves and fhiit. - Visible insects can be removed by hand (with gloves or tweezers) and placed in soapy water or vegetable oil. Alternatively, insects can be sprayed off the plant with water or in some cases vacuumed off of larger plants. - Store-bought traps, such as species-specific, pheromone-based traps or colored sticky cards, can be used. Slugs can be trapped in small cups filled wdth beer that are set in the ground so the slugs can get in easily. - In cases where microscopic parasites, such as bacteria and fungi, are causing damage to plants, the affected plant material can be removed and disposed of (pmning equipment should be disinfected with bleach to prevent spreading the disease organism). - Small mammals and birds can be excluded using fences, netting, tree tmnk guards. - Beneficial organisms, such as bats, birds, green lacewings, ladybugs, praying mantis, ground beetles, parasitic nematodes, trichogramma wasps, seed head weevils, and spiders that prey on detrimental pest species can be promoted. • FoUow aU federal, state, and local laws and regulations governing the use, storage, and disposal of fertUizers and pesticides and training of applicators and pest control advisors. January 2003 California Stormwater BMP Handbook 3 of 6 Municipal www.cabmphandbooks.com SC-73 Landscape Maintenance • Use pesticides only if there is an actual pest problem (not on a regular preventative schedule). • Do not use pesticides if rain is expected. Apply pesticides only when wind speeds are low Gess than 5 mph). • Do not mix or prepare pesticides for application near storm drains. • Prepare the minimum amount of pesticide needed for the job and use the lowest rate that wiU effectively control the pest. • Employ techniques to minimize off-target application (e.g. spray drift) of pesticides, including consideration of altemative application techniques. • FertUizers should be worked into the soil rather than dumped or broadcast onto the surface. • Calibrate fertUizer and pesticide application equipment to avoid excessive application. • Periodically test soUs for determining proper fertilizer use. • Sweep pavement and sidewalk if fertUizer is spUled on these surfaces before applying irrigation water. • Purchase only the amount of pesticide that you can reasonably use in a given time period (month or year depending on the product). • Triple rinse containers, and use rinse water as product. Dispose of unused pesticide as hazardous waste. • Dispose of empty pesticide containers according to the instmctions on the container label, /nspection • Inspect irrigation system periodically to ensure that the right amount of water is being applied and that excessive mnoff is not occurring. Minimize excess watering, and repair leaks in the irrigation system as soon as they are observed. • Inspect pesticide/fertUizer equipment and transportation vehicles daily. TVainingf • Educate and train employees on use of pesticides and in pesticide application techniques to prevent poUution. Pesticide application must be under the supervision of a California qualified pesticide applicator. • Train/encourage municipal maintenance crews to use IPM techniques for managing public green areas. • Annually train employees within departments responsible for pesticide application on the appropriate portions of the agency's IPM Policy, SOPs, and BMPs, and the latest IPM techniques. 4 of 6 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Landscape Maintenance SC-73 • Employees who are not authorized and trained to apply pesticides should be periodically (at least annually) informed that they cannot use over-the-counter pesticides in or around the workplace. • Use a training log or simUar method to document training. SpiH Response and Preucntion • Refer to SC-ii, Spill Prevention, Control & Cleanup • Have spUl cleanup materials readily avaUable and in a know in location • Cleanup spiUs immediately and use dry methods if possible. • Properly dispose of spill cleanup material. Other Considerations m The Federal Pesticide, Fungicide, and Rodenticide Act and Califomia Titie 3, Division 6, Pesticides and Pest Control Operations place strict controls over pesticide application and handling and specify training, annual refresher, and testing requirements. The regulations generally cover: a list of approved pesticides and selected uses, updated regularly; general application information; equipment use and maintenance procedures; and record keeping. The California Department of Pesticide Regulations and the County Agricultural Commission coordinate and maintain the licensing and certification programs. All public agency employees who apply pesticides and herbicides in "agricultural use" areas such as parks, golf courses, rights-of-way and recreation areas should be properly certified in accordance with state regulations. Contracts for landscape maintenance should include similar requirements. • All employees who handle pesticides should be familiar with the most recent material safety datasheet (MSDS) files. • Municipalities do not have the authority to regulate the use of pesticides by school districts, however the California Healthy Schools Act of 2000 (AB 2260) has imposed requirements on Califomia school districts regarding pesticide use in schools. Posting of notification prior to the application of pesticides is now required, and IPM is stated as the preferred approach to pest management in schools. Requirements Costs Additional training of municipal employees wlU be required to address IPM techniques and BMPs. IPM methods will likely increase labor cost for pest control which may be offset by lower chemical costs. Maintenance Not applicable January 2003 Califomia Stormwater BMP Handbook 5 of 6 Municipal www.cabmphandbooks.com SC-73 Landscape Maintenance Supplemental Information Further Detail ofthe BMP Waste Management Composting is one of the better disposal alternatives if locally avaUable. Most municipalities either have or are planning yard waste composting facUities as a means of reducing the amount of waste going to the landfill. Lawn clippings from municipal maintenance programs as weU as private sources would probably be compatible with most composting facUities Contractors and Other Pesticide Users Municipal agencies should develop and implement a process to ensure that any contractor employed to conduct pest control and pesticide application on municipal property engages in pest control methods consistent with the IPM Policy adopted by the agency. Specifically, municipalities should require contractors to follow the agency's IPM policy, SOPs, and BMPs; provide evidence to the agency of having received training on current IPM techniques when feasible; provide documentation of pesticide use on agency property to the agency in a timely manner. References and Resources King County Stormwater PoUution Control Manual. Best Management Practices for Businesses. 1995. King County Surface Water Management. July. On-line: http://dnr.metrokc.gov/wlr/dss/spcm.htm Los Angeles County Stormwater Quality Model Programs. Public Agency Activities http://ladpw.org/wmd/npdes/model links.cfm Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for SmaU Municipalities. Prepared by City of Monterey, City of Santa Cmz, California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. Orange County Stormwater Program http://www.ocwatersheds.com/StormWater/swp introduction .asp Santa Clara Valley Urban Runoff Pollution Prevention Program. 1997 Urban Runoff Management Plan. September i997, updated October 2000. United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Landscaping and Lawn Care. Office of Water. Office of Wastewater Management. On-line: http://www.epa.gov/npdes/menuofbmps/poU 8.htm 6 of 6 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Drainage System Maintenance SC-74 Objectives Contain Educate Reduce/Minimize Photo Credit: Geoff Brosseau Description As a consequence of its function, the stormwater conveyance system collects and transports urban mnoff that may contain certain pollutants. Maintaining catch basins, stormwater inlets, and other stormwater conveyance structures on a regular basis win remove pollutants, prevent clogging of the downstream conveyance system, restore catch basins' sediment trapping capacity, and ensure the system functions properly hydraulically to avoid flooding. Approach Suggested Protocols Catch Basins/Inlet Structiire.'i m Municipal staff should regularly inspect facUities to ensure the following: Immediate repair of any deterioration threatening structural integrity. Cleaning before the sump is 40% fuU. Catch basins should be cleaned as frequently as needed to meet this standard. Stenciling of catch basins and inlets (see SC-75 Waste Handhng and Disposal). • Clean catch basins, storm drain inlets, and other conveyance stractures in high pollutant load areas just before the wet season to remove sediments and debris accumulated during the summer. Targeted Constituents Sediment Nutrients Trash Metals Bactena Oil and Grease Organics Oxygen Demanding SQA I raiifornia Stormwater Quality Association January 2003 California Stormwater BMP Handbook Municipal www.cabmphandbooks.com 1 of 9 SC-74 Drainage System Maintenance • Conduct inspections more frequently during the wet season for problem areas where sediment or trash accumulates more often. Clean and repair as needed. • Keep accurate logs of the number of catch basins cleaned. • Record the amount of waste collected. • Store wastes coUected from cleaning activities of the drainage system in appropriate containers or temporary storage sites in a manner that prevents discharge to the storm drain. • Dewater the wastes with outflow into the sanitary sewer if permitted. Water should be treated with an appropriate filtering device prior to discharge to the sanitary sewer. If discharge to the sanitary sewer is not allowed, water should be pumped or vacuumed to a tank and properly disposed of. Do not dewater near a storm drain or stream. • Except for small communities with relatively few catch basins that may be cleaned manually, most municipalities will require mechanical cleaners such as eductors, vacuums, or bucket loaders. Storm Drain Conveyance System u Locate reaches of storm drain with deposit problems and develop a flushing schedule that keeps the pipe clear of excessive buildup. • Collect flushed effiuent and pump to the sanitaiy sewer for treatment. Pump Stations • Qean all storm drain pump stations prior to the wet season to remove silt and trash. • Do not allow discharge from cleaning a storm drain pump station or other facUity to reach the storm drain system. • Conduct quarterly routine maintenance at each pump station. • Inspect, clean, and repair as necessary all outlet stmctures prior to the wet season. • Sample coUected sediments to determine if landfiU disposal is possible, or Ulegal discharges in the watershed are occurring. Open Channel u Consider modification of storm channel characteristics to improve channel hydraulics, to increase pollutant removals, and to enhance channel/creek aesthetic and habitat value. • Conduct channel modification/improvement in accordance with existing laws. Any person, govemment agency, or public utUity proposing an activity that will change the natural (emphasis added) state of any river, stream, or lake in California, must enter into a steam or Lake Alteration Agreement with the Department of Fish and Game. The developer-applicant should also contact local governments (city, county, special districts), other state agencies 2 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Drainage System Maintenance SC-74 (SWRCB, RWQCB, Department of Forestry, Department of Water Resources), and Federal Corps of Engineers and USFWS Illicit Connections and Discharges m During routine maintenance of conveyance system and drainage stmctures field staff should look for evidence of illegal discharges or illicit connections: Is there evidence of spills such as paints, discoloring, etc. Are there any odors associated with the drainage system Record locations of apparent illegal discharges/Ulicit connections - Track flows back to potential dischargers and conduct aboveground inspections. This can be done through visual inspection of up gradient manholes or altemate techniques including zinc chloride smoke testing, fluorometric dye testing, physical inspection testing, or television camera inspection. Once the origin of flow is established, require Ulicit discharger to eliminate the discharge. • Stencil storm drains, where applicable, to prevent illegal disposal of pollutants. Storm drain inlets should have messages such as "Dump No Waste Drains to Stream" stenciled next to them to wam against ignorant or intentional dumping of pollutants into the storm drainage system. • Refer to fact sheet SC-io Non-Stormwater Discharges. Illegal Dumping • Regularly inspect and clean up hot spots and other storm drainage areas where illegal dumping and disposal occurs. • Establish a system for tracking incidents. The system should be designed to identify the following: Illegal dumping hot spots Types and quantities (in some cases) of wastes Patterns in time of occurrence (time of day/night, month, or year) Mode of dumping (abandoned containers, "midnight dumping" from moving vehicles, direct dumping of materials, accidents/spills) Responsible parties • Post "No Dumping" signs in problem areas with a phone number for reporting dumping and disposal. Signs should also indicate fines and penalties for illegal dumping. • Refer to fact sheet SC-io Non-Stormwater Discharges. January 2003 California Stormwater BMP Handbook 3 of 9 Municipal www.cabmphandbooks.com SC-74 Drainage System Maintenance • The State Department of Fish and Game has a hotline for reporting violations caUed Cal TIP (1-800-952-5400). The phone number may be used to report any violation of a Fish and Game code (illegal dumping, poaching, etc.). • The California Department of Toxic Substances Control's Waste Alert Hotline, 1-800- 69TOXIC, can be used to report hazardous waste violations. TVainingf • Train crews in proper maintenance activities, including record keeping and disposal. • Only properly trained individuals are allowed to handle hazardous materials/wastes. • Train municipal employees from all departments (public works, utilities, street cleaning, parks and recreation, industrial waste inspection, hazardous waste inspection, sewer maintenance) to recognize and report illegal dumping. • Train municipal employees and educate businesses, contractors, and the general public in proper and consistent methods for disposal. • Train municipal staff regarding non-stormwater discharges (See SC-10 Non-Stormwater Discharges). SpiZZ Response and Prevention m Refer to SC-11, Prevention, Control & Cleanup • Have spUl cleanup materials readily available and in a known location. • Cleanup spills immediately and use dry methods if possible. • Properly dispose of spUl cleanup material. Other Considerations • Cleanup activities may create a slight disturbance for local aquatic species. Access to items and material on private property may be limited. Trade-offs may exist between channel hydraulics and water quality/riparian habitat. If storm channels or basins are recognized as wetlands, many activities, including maintenance, may be subject to regulation and permitting. • Storm drain flushing is most effective in small diameter pipes (36-inch diameter pipe or less, depending on water supply and sediment collection capacity). Other considerations associated with storm drain flushing may include the availability of a water source, finding a downstream area to collect sediments, liquid/sediment disposal, and disposal of flushed effiuent to sanitary sewer may be prohibited in some areas. • Regulations may include adoption of substantial penalties for iUegal dumping and disposal. • Municipal codes should include sections prohibiting the discharge of soil, debris, refuse, hazardous wastes, and other poUutants into the storm drain system. • Private property access rights may be needed to track Ulegal discharges up gradient. 4 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Drainage System Maintenance SC-74 • Requirements of municipal ordinance authority for suspected source verification testing for illicit connections necessary for guaranteed rights of entry. Requirements Costs • An aggressive catch basin cleaning program could require a significant capital and OScM budget. A careful study of cleaning effectiveness should be undertaken before increased cleaning is implemented. Catch basin cleaning costs are less expensive if vacuum street sweepers are avaUable; cleaning catch basins manually can cost approximately twice as much as cleaning the basins with a vacuum attached to a sweeper. • Methods used for Ulicit connection detection (smoke testing, dye testing, visual inspection, and flow monitoring) can be costly and time-consuming. Site-specific factors, such as the level of impervious area, the density and ages of buUdings, and type of land use will determine the level of investigation necessary. Encouraging reporting of illicit discharges by employees can offset costs by saving expense on inspectors and directing resources more efficientiy. Some programs have used funds available from "environmental fees" or special assessment districts to fund their illicit connection elimination programs. Maintenance • Two-person teams may be required to clean catch basins with vactor tmcks. • Identifying illicit discharges requires teams of at least two people (volunteers can be used), plus administrative personnel, depending on the complexity of the storm sewer system. • Arrangements must be made for proper disposal of collected wastes. • Requires technical staff to detect and investigate illegal dumping violations, and to coordinate public education. Supplemental Information Further Detail ofthe BMP Storm Drain flushing Sanitary sewer flushing is a common maintenance activity used to improve pipe hydraulics and to remove poUutants in sanitary sewer systems. The same principles that make sanitary sewer flushing effective can be used to flush storm drains. Flushing may be designed to hydraulically convey accumulated material to strategic locations, such as to an open channel, to another point where flushing will be initiated, or over to the sanitary sewer and on to the treatment facilities, thus preventing re-suspension and overflow of a portion of the solids during storm events. Flushing prevents "plug flow" discharges of concentrated pollutant loadings and sediments. The deposits can hinder the designed conveyance capacity of the storm drain system and potentially cause backwater conditions in severe cases of clogging. Storm drain flushing usually takes place along segments of pipe with grades that are too flat to maintain adequate velocity to keep particles in suspension. An upstream manhole is selected to place an inflatable device that temporarily plugs the pipe. Further upstream, water is pumped into the line to create a flushing wave. When the upstream reach of pipe is sufficiently fiUl to January 2003 California Stormwater BMP Handbook 5 of 9 Municipal www.cabmphandbooks.com SC-74 Drainage System Maintenance cause a flushing wave, the inflated device is rapidly deflated with the assistance of a vacuum pump, releasing the backed up water and resulting in the cleaning of the storm drain segment. To further reduce the impacts of stormwater pollution, a second inflatable device, placed well downstream, may be used to re-collect the water after the force of the flushing wave has dissipated. A pump may then be used to transfer the water and accumulated material to the sanitary sewer for treatment. In some cases, an interceptor stmcture may be more practical or required to re-collect the flushed waters. It has been found that cleansing efficieuQ' of periodic flush waves is dependent upon flush volume, flush discharge rate, sewer slope, sewer length, sewer flow rate, sewer diameter, and population density. As a mle of thumb, the length of line to be flushed should not exceed 700 feet. At this maximum recommended length, the percent removal efficiency ranges between 65- 75 percent for organics and 55-65 percent for dry weather grit/inorganic material. The percent removal efficiency drops rapidly beyond that. Water is commonly supplied by a water tmck, but fire hydrants can also supply water. To make the best use of water, it is recommended that reclaimed water be used or that fire hydrant line flushing coincide with storm drain flushing. Flow Management Flow management has been one of the principal motivations for designing urban stream corridors in the past. Such needs may or may not be compatible with the stormwater quality goals in the stream corridor. Downstream flood peaks can be suppressed by reducing through flow velocity. This can be accomplished by reducing gradient with grade control stmctures or increasing roughness with boulders, dense vegetation, or complex banks forms. Reducing velocity correspondingly increases flood height, so all such measures have a natural association with floodplain open space. Flood elevations laterally adjacent to the stream can be lowered by increasing through flow velocity. However, increasing velocity increases flooding downstream and inherently conflicts with channel stabUity and human safety. Where topography permits, another way to lower flood elevation is to lower the level of the floodway with drop stmctures into a large but subtly excavated bowl where flood flows we allowed to spread out. Stream Corridor Planning Urban streams receive and convey stormwater flows from developed or developing watersheds. Planning of stream corridors thus interacts with urban stormwater management programs. If local programs are intended to control or protect downstream environments by managing flows delivered to the channels, then it is logical that such programs should be supplemented by management of the materials, forms, and uses of the dovrastream riparian corridor. Any proposal for steam alteration or management should be investigated for its potential flow and stability effects on upstream, downstream, and laterally adjacent areas. The timing and rate of flow from various tributaries can combine in complex ways to alter flood hazards. Each section of channel is unique, influenced by its own distribution of roughness elements, management activities, and stream responses. 6 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Drainage System Maintenance SC-74 FlexibUity to adapt to stream features and behaviors as they evolve must be included in stream reclamation planning. The amenity and ecology of streams may be enhanced through the landscape design options of i) corridor reservation, 2) bank treatment, 3) geomorphic restoration, and 4) grade control. Corridor reservation - Reserving stream corridors and valleys to accommodate natural stream meandering, aggradation, degradation, and over bank flows allows streams to find their own form and generate less ongoing erosion. In California, open stream corridors in recent urban developments have produced recreational open space, irrigation of streamside plantings, and the aesthetic amenity of flowing water. Bank treatment - The use of armoring, vegetative cover, and flow deflection may be used to influence a channel's form, stability, and biotic habitat. To prevent bank erosion, armoring can be done with rigid constmction materials, such as concrete, masonry, wood planks and logs, riprap, and gabions. Concrete linings have been criticized because of their lack of provision of biotic habitat. In contrast, riprap and gabions make relatively porous and flexible linings. Boulders, placed in the bed reduce velocity and erosive power. Riparian vegetation can stabilize the banks of streams that are at or near a condition of equilibrium. Binding networks of roots increase bank shear strength. During flood flows, resilient vegetation is forced into erosion-inhibiting mats. The roughness of vegetation leads to lower velocity, further reducing erosive effects. Stmctural flow deflection can protect banks from erosion or alter fish habitat. By concentrating flow, a deflector causes a pool to be scoured in the bed. Geomorphic restoration - Restoration refers to alteration of disturbed streams so their form and behavior emulate those of undisturbed streams. Natural meanders are retained, with grading to gentle slopes on the inside of curves to allow point bars and riffle-pool sequences to develop. Trees are retained to provide scenic quality, biotic productivity, and roots for bank stabilization, supplemented by plantings where necessary. A restorative approach can be successful where the stream is already approaching equilibrium. However, if upstream urbanization continues new flow regimes will be generated that could dismpt the equUibrium of the treated system. Grade Control - A grade control stmcture is a level shelf of a permanent material, such as stone, masonry, or concrete, over which stream water flows. A grade control stmcture is called a sill, weir, or drop stmcture, depending on the relation of its invert elevation to upstream and downstream channels. A sUl is installed at the preexisting channel bed elevation to prevent upstream migration of nick points. It establishes a firm base level below which the upstream channel can not erode. A weir or check dam is instaUed with invert above the preexisting bed elevation. A weir raises the local base level of the stream and causes aggradation upstream. The gradient, velocity, and erosive potential of the stream channel are reduced. A drop stmcture lowers the downstream invert below its preexisting elevation, reducing downstream gradient and velocity. Weirs and drop stmcture control erosion by dissipating energy and reducing slope velocity. January 2003 California Stormwater BMP Handbook 7 of 9 Municipal www.cabmphandbooks.com SC-74 Drainage System Maintenance When carefully applied, grade control stmctures can be highly versatile in establishing human and environmental benefits in stabilized channels. To be successful, application of grade control stmctures should be guided by analysis of the stream system both upstream and downstream from the area to he reclaimed. Examples The California Department of Water Resources began the Urban Stream Restoration Program in 1985. The program provides grant funds to municipalities and community groups to implement stream restoration projects. The projects reduce damages from streambank aid watershed instabUity arid floods while restoring streams' aesthetic, recreational, and fish and wildlife values. In Buena Vista Park, upper floodway slopes are gentle and grassed to achieve continuity of usable park land across the channel of small boulders at the base of the slopes. The San Diego River is a large, vegetative lined channel, which was planted in a variety of species to support riparian vrildlife while stabilizing the steep banks of the floodway. References and Resources Ferguson, B.K. 1991. Urban Stream Reclamation, p. 324-322, Journal of SoU and Water Conservation. Los Angeles County Stormwater Quality. Public Agency Activities Model Program. On-line: http://ladpw.org/wmd/npdes/public TC.cfm Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipalities. Prepared by City of Monterey, City of Santa Cmz, California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July. 1998. Orange County Stormwater Program http://vyww.ocwatersheds.com/StormWater/svyp introduction.asp Santa Clara Valley Urban Runoff Pollution Prevention Program. 1997 Urban Runoff Management Plan. September 1997, updated October 2000. San Diego Stormwater Co-permittees Jurisdictional Urban Runoff Management Program (URMP) Municipal Activities Model Program Guidance. 2001. Project Clean Water. November. United States Environmental Protection Agency (USEPA). 1999. Stormwater Management Fact Sheet Non-stormwater Discharges to Storm Sewers. EPA 832-F-99-022. Office of Water, Washington, D.C. September. United States Environmental Protection Agency (USEPA). 1999. Stormwater O&M Fact Sheet Catch Basin Cleaning. EPA 832-F-99-011. Office of Water, Washington, D.C. September. 8 of 9 California Stormwater BMP Handbook January 2003 Municipal www.cabmphandbooks.com Drainage System Maintenance SC-74 United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Illegal Dumping Control. On line: http://www.epa.gov/npdes/menuofbmps/poll 7.htm United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Storm Drain System Cleaning. On line: http://www.epa.gov/npdes/menuofbmps/poll i6.htm January 2003 California Stormwater BMP Handbook 9 of 9 Municipal WW w. ca bm pha nd boo ks.com APPENDIX B Coastal Rail Trail Inspection Form Day and Date: Report No. Inspector: Weather: sunny/overcast/cloudy/rain Temp: OK - satisfactory, /-Maintained (with description of maintenance); •- corrective action required Item Condition Corrective Action/Comment 1 Shoulder/grass mowing/trimming 2 Trees (General health, irrigation, pest issues) 3 Plant health (General health, irrigation, pest issues) 4 Mulch 5 Weed control 6 Irrigation check 7 Bollard 8 Trash 9 Graffiti 10 Public Art 11 Drinking Fountains 12 Benches 13 Hardscape/Paving (Potholes) (horizontal/vertical cracks) sealing/repaving 14 Pavement cleanliness (sweeping required) 15 Trail/Decorative directional signage 16 Street signs 17 Pavement markings 18 Lighting 19 Emergency telephones 20 Drainage Vegetated swales Are swales completely draining Is there evidence of erosion Have areas that needed repair been reseeded and growing Is vegetation less than 6 inches high Are trees and shmbs in swale Is vegetation control needed Inlet Is inlet functioning properly Is trash in inlet Follow-up Trail Coordinator Review APPENDIX C HYDROLOGY CALCULATIONS City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #1 Storm Drain 'A' Catch Basin PROPOSED CONDITION: P6= 2.3 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area c L H Tc 1 S d Q Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 44.20 Type F CB in sag 0.07 0.51 48 0.8 6.21 5.27 1.67 0.6 0,19 8 2.4 CONCLUSION: The depth and spread width of flow are sufficient lo prevent flooding into adjacent property or the bikepath. I— INLET ANALYSIS: 100 Year Storm CO Watershed #1 111 Storm Drain 'A' Catch Basin PROPOSED CONDITION: P6= 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Descnption Area C L H Tc 1 S d Q Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 44.20 Type F CB in sag 0.07 0.51 48 0.8 6.21 6.19 1.67 0-6 0.23 8 2.7 CONCLUSION: The depth and spread width of flow are sufficient to prevent flooding into adjacent property or the bikepath. EOUATIONS: Tc = [1.8(1 .1-C}L'^^S°^^ Figure 3-5 San Diego Hydrology Manual I = 7.44 X P5 X Tc""^ Figure 3-2 San Diego Hydrology Manual 0 = Cx 1 X A C = Soil Group B, Residentiat, 7.3 DU/A or less, Table 3-1 San Diego County Hydrology Manual L=Hydraulica!ly most remote flow path of watershed area d=depth of water per Chart 11 HEC 12 Inlet L=4' (1.2meters) tor a Type F Catch Basin with one side open, 8' (2.4 meters) with both sides open Spread = spread width of flow at 2% cross slope NOTE: See exhibit "Proposed Conditions Hydrology Map," dated 3/2/04, for reference. Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #2 Storm Drain 'B" Catch Basin PROPOSED CONDITION: P6= 2.3 in. (adjusted per Figure 3-1 San Dlego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. ft 43.60 Description Type F CB in sag Area ac 0.24 0.51 562 2.4 Tc mm 34.42 in/hr 1.75 0.41 0.6 Q cfs 0,22 Inlet L ft CONCLUSION: The depth and spread width of flow are sufficient to prevent flooding into adjacent property or the bikepath. Spread ft 2.6 CO LU INLET ANALYSIS: 100 Year Storm Watershed #2 Storm Drain 'B' Catch Basin PROPOSED CONDITION: P6= 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc - 5 min. Location FL El. ft 43.60 Description Type F CB in sag Area ac 0.24 0.51 582 2.4 Tc mm 34.42 in/hr 2,05 0.41 0,7 Q cfs 0.25 Inlet L ft CONCLUSION: The depth and spread width of flow are sufficient to prevent flooding into adjacent property or the bikepath. Spread 2.9 EQUATIONS: Tc = [1.8(1.1 -C)L° ^3° " Figure 3-5 San Diego Hydrology Manual I = 7.44 X Pe X Tc" Figure 3-2 San Diego Hydrology Manual Q ^ C x I X A C = Soil Group B, Residential, 7.3 DU/A or less, Table 3-1 San Diego County Hydrology Manual L=Hydfaulically most remote flow path of watershed area d^depth of water per Chart 11 HEC 12 Inlet L^4' (1.2meters) for a Type F Catch Basin with one side open, 8' (2.4 meters) wilh both sides open Spread = spread width of flow at 2% cross slope Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #5 Catch Basin into Exst RCP Pe- 2.3 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. PROPOSED COND TION: Location FL El. Description Area C L H Tc 1 S d 0 Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 43.60 Type F CB in sag 0.37 0.51 880 2.4 48.58 1.40 0.27 0.7 0.26 8 3.0 CONCLUSION: The depth and spread width of fiow are sufficient to prevent flooding into adjacent property or the bikepath. INLET ANALYSIS: 100 Year Storm Watershed #5 Storm Drain 'B' Catch Basin PROPOSED CONDITION: Pe- 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area C L H Tc 1 S d Q Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 43.60 Type F CB in sag 0.37 0.51 880 2.4 48.58 1.64 0,27 0.8 0.31 8 3.3 CONCLUSION: The depth and spread width of flow are sufficient to prevent flooding into adjacent property or the bikepath. EQUATIONS: Tc - [1.8(1.1-C)L''^]/S°^^ Figure 3-5 San Diego Hydrology Manual I = 7.44 X P5 X Tc" Figure 3-2 San Diego Hydrology Manual Q = Cx1 xA C = Soil Group B, Residenfial, 7.3 DU/A or less. Table 3-1 San Diego County Hydrology Manual L-Hydraulically most remote flow path of watershed area d=depth of water per Chart 11 HEC 12 Inlet L-4' (1.2meters) for a Type F Catch Basin with one side open, 8' (2,4 meters) with both sides open Spread = spread width of flow at 2% cross slope Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #8 Storm Drain 'C Catch Basin PROPOSED CONDITION: Ps- 2.3 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area C L H Tc 1 S d Q Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 41.00 Type F CB in sump 0.26 0.51 725 4.8 32.81 1.80 0.66 0.7 0.24 8 2.8 CONCLUSION: The depth and spread width of flow are sufficient to prevent flooding into adjacent property or the bikepath. INLET ANALYSIS: 100 Year Storm Watershed #8 Storm Drain 'C Catch Basin PROPOSED CONDITION: P6= 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area C L H Tc 1 S d O Inlet L Spread ft ac ft ft min in/hr % in cfs ft ft 41.00 Type F CB in sump 0.26 0.51 725 4.8 32.81 2.11 0.66 0.8 0.28 8 3.1 CONCLUSION: The depth and spread width of flow are sufticient to prevent flooding into adjacent property or the bikepath. EQUATIONS: Tc = [1.8(1.1-C)L°^/S°^ Figure 3-5 San Diego Hydrology Manual I = 7.44 X Pg X Tc"-^^ Figure 3-2 San Dlego Hydrology Manual Q = CxI xA C = Soil Group B, Residential, 7.3 DU/A or less. Table 3-1 San Diego County Hydrology Manual L=Hydraulically most remote flow path of watershed area d^depth of water per Chart 11 HEC 12 Inlet L=4' {1.2meters) for a Type F Catch Basin with one side open, 8' (2,4 meters) with both sides open Spread = spread width of flow at 2% cross slope Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #9 Storm Drain 'D' Catch Basin PROPOSED CONDITION: P6= 2.3 in. (adjusted per Figure 3-1 San Dlego County Hydrology Manual) Minimum Tc = 5 min. Location FL EI. Description Area (9a) c, L H Tc, 1, S Qip ft ac ft ft min in/hr % cfs 40,00 Type F CB in sump 0,93 0.80 435 6.0 10,12 3.85 1.38 2.87 Area (9b) C, L H Tc3 S O20 ac ft ft min in/hr % cfs 0.06 0,51 146 1.0 14.56 3.04 0.68 0.09 Or, QT? 9a and 9b junction method: cfs cfs cfs 9a and 9b junction method: 2.93 2.36 2.93 Area(9c) C, L H Tc3 I3 S Q d Inlet L ac ft ft min in/hr % cfs cfs in ft 0.11 0.51 286 2.0 20.23 2.46 0.70 0.14 3.07 3.7 8 INLET ANALYSIS: 100 Year Storm Watershed #9 Storm Drain 'D' Catch Basin PROPOSED CONDITION: PG- 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area (9a) c, L H T., 1, S Q,o ft ac ft ft min in/hr % cfs 40.00 Type F CB in sump 0.93 0.80 435 6.0 10.12 4.51 1.38 3.37 Area (9b) L H T.2 S Q^p ac ft ft min in/hr % cfs 0.06 0.51 146 1.0 14.56 3.57 0.68 0.11 QT, QT? 9a and 9b junction method: cfs cfs cfs 3.44 2,771 3,44 Area (9c) Cs L H T.3 I3 S Q Qtota! d Inlet L ac ft ft min in/hr % cfs cfs in ft 0.11 0.51 286 2.0 20,23 2.89 0.70 0.16 3.61 4.1 8 CONCLUSION: To avoid potential flooding, watershed area 9c must be graded such that its boundaries are 4.1" above the flow line of the catch basin. EQUATIONS: Tc = [1.8(1.1 -OL^^j/S" Figure 3-5 San Diego Hydrology Manual I = 7 44 X p6 X Tc"""" Figure 3-2 San Diego Hydrology Manual Q = Cxl X A C, = Pavement, 80% impervious, = Soil Group B, Residential, 7 3 DU/A or less, Table 3-1 San Diego County Hydrology Manual L=Hydrau!icaIly most remote tlow path of walersfied area d=depin ol v/ater per Utiarl 11 HtC Ik Inlet L=4' (1,2meters) for a Type F Catch Basin with one side open, 8' (2.4 meters) with both sides open QTI=QI„-(-TC,/T^2{QJP) [Junction Mettiod San Diego County Hydrology Manual) Qr2^Q2y-fl2/ii(Q,p) (Junction fwlethod San Diego County Hydrology Manual) Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #11 Type A Inlet ULTIMATE: Ps- 2.3 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location Description Area C L H Tc 1 Q S y V a Req'd L ac ft ft min in/hr cfs % ft fps ft ft Type A Inlet on grade 0.34 1.0 388 7,8 5.00 6.06 2,04 2.00 0.26 3.1 0.33 7 CONCLUSION: 7" will intercept 100% of the 50-year flow, however, 8' is recommended to intercept 100% of the 100-year ftow. INLET ANALYSIS: 100 Year Storm Watershed #11 Type A Inlet ULTIMATE: P6= 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location Description Area C L H Tc 1 Q S y V a Req'd L ac ft ft min in/hr cfs % ft fps ft ft Type A Iniet on grade 0.34 1.0 388 7.8 5-00 7.11 2.40 2.00 0.26 3.1 0.33 8 CONCLUSION: 8' will intercept the 100-year flow with no bypass. EQUATIONS Tc - [1.8(1.1-C)L° ^j/S" Figure 3-5 San Dlego Hydrology Manual I = 7.44 X Ps X Tc" Q = C X IxA y - depth of flow in approach based on Appendix X-D of the County of San Diego Design and Procedure Manual V ^ velocity of flow in approach based on Appendix X-0 of the County of San Diego Design and Procedure Manual a = depth of depression per City of Carlsbad DS-1 "Local Depression" for curb inlets except for median inlets in super elevated crossfalls. Required L -Q / ( 0.7 x ( a -n y )' ^) C = Pavement, 100% Impervious Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rail Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #12 Existing Catch Basin PROPOSED CONDITION: Pe- 2.3 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area^ C L H Ti 1 Qi ft ac ft ft min in/hr cfs 36.53 Exst CB in sag 0.12 initial area 0.77 75 1.5 4.00 7.00 0.62 Areat, C L QAVG lavo Tt S V ac ft cfs cfs min % fps 1.76 gutter flow 0.77 383 78 8.2 1.93 1.50 3.30 Tc r Qlolal Inlet L opening height (in) min in/hr cfs ft opening height (in) in 5.93 5.43 7.8 6.0 9 8.3 CONCLUSION: The 50-year depth will be contained by the existing concrete channel (depth of 1') which directs flows into the 9 inch high catch basin opening. INLET ANALYSIS: 100 Year Storm Watershed #12 Existing Catch Basin PROPOSED CONDITION: PG- 2.7 in. (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc = 5 min. Location FL El. Description Area^ C L H Ti 1 Qi ft ac ft ft min in/hr cfs 36.53 Exst CB in sag 0.12 initial area 0.77 75 1,5 4.00 8.22 0.73 Areai, C L QAVG Tt S V ac ft cfs cfs min % fps 176 gutter flow 0.77 383 9.3 9.7 1.80 1.50 3.55 T. r Qlolat Inlet L opening height (in) min in/hr cfs ft opening height (in) in 5.80 6.47 9.3 6.0 9 9.3 CONCLUSION: The 100-year depth will be contained by the existing concrete channel (depth of 1"). The Catch Basin opening will begin a transition to orifice flow. EQUATIONS: Ti 4 min Table 3-2 San Diego County Hydrology Manual. T^ - Ti -t- Tt O, = C x I x A i = 7.44 X Ps X Ti" !• - 7.44 x Pg x T," Tt = LA/ V ^ velocity of flow in approach based on Appendix X-D of the County of San Diego Design and Procedure Manual d=depth of water per Chart 11 HEC 12 C = Soil Group B, Neighborhood Comerciai QAVG=Q, + ({qav,y2)-Areab) Qa,,^ = estimated until QAVG = Qt. Qtoiai = I' (Area^ * C^ + Area.' C, Prepared by Dokken Engineering 3/2/04 City of Carlsbad Coastal Rait Trail Phase 1 Hydrology Calculations INLET ANALYSIS: 50 Year Storm Watershed #6 (including 3,4,7,10 - see note below) Concrete Swale PROPOSED CONDITION: P6= 2.3 (adjusted per Figure 3-1 San Diego County Hydrology Manual) Minimum Tc=:5min. Description Area C L H Tc 1 S Q ac ft ft min in/hr % cfs Concrete Swale 0.30 0.85 520 2.6 12.93 3.28 0.50 0.83 channel section. INLET ANALYSIS: 100 Year Storm Watershed #6 (Including 3,4,7,10 - see note below) Concrete Swale PROPOSED CONDITION: P6= 2.7 (adjusted per Figure 3-1 San IXego County Hydrology Manual) Minimum Tc = 5 min. Description Area C L H Tc 1 S Q ac ft ft min in/hr % cfs Concrete Swale 0.30 0.85 520 2.6 12.93 3.85 0.50 0.97 channel section. EQUATIONS: Tc = [1.8(1.1 -C)L° ^°-^ Figure 3-5 San Diego Hydrology Manual I = 7.44 X Pfi X Tc' Figure 3-2 San Diego Hydrology Manual Q = CxlxA C = Pavement, 85% Impenrious L=Hydraulically most remote ftow path of watersfied area Hydraulic Output: Results Flow Element Circular Channel Depth 0.31 ft Method Manning's Formula Flow Area 0.4 ft2 Solve For Channel Depth Wetted Perimeter 1.81 fl Top Width 0 ft Inout Data Critic^ Depth 0.32 ft Mannings Coefficient 0.013 Percent Full 12.5 % Channel Slope 0.005 ft/ft Critical Slope 0 ft/ft Diameter 30 in Velocity 2.73 ft/s Discharge 0.97 cfs Velocity Head 0.12 ft Specific Energy 0.43 fl Froude Number 1.04 Maximum Discharge 31.2 cfs Discharge Full 29 cfs Slope Full 0 ft/ft Flow Type Supercritical Depth Is contained by smie Project Engineer: Dokken Engineering FlowMaster v7.0 [7.0X5] 2/6/2004 1:28 PM © Haestad Methods, Inc. 37 Brookside Road Waterbuty. CT 06708 USA 8 +1-203-755-1666 3/2/04