STORMWATER Best Management Practices for East Baton Rouge Parish - Master Development Program City of Baton Rouge - Parish of East Baton Rouge City Parish Planning Commission CPPC EAST BATON ROUGE MASTER DEVELOPMENT PROGRAM STORMWATER Best Management Practices East Baton Rouge Parish - Master Development Program Made possible in part by grants from the Louisiana Department of Environmental Quality July 2007 in collaboration with BROWN+DANOS landdesign, inc. MISSION STATEMENT MISSION STATEMENT “It is an undisputable fact that most, if not all, land development and public improvement projects have an impact on the natural conditions of adjacent areas. Unfortunately, this impact is negative due to the intrusion of civilization upon any environment. The purpose of the (committee) is to minimize or eliminate these adverse impacts through the promulgation of guidelines, policies and procedures designed to protect the environmental quality of surrounding areas and water bodies, through education of the public; and through utilization of existing environmental systems integrated with urban planning.” City-Parish Wetlands Steering Committee, 2006. EAST BATON ROUGE MASTER DEVELOPMENT PROGRAM CONTENTS CHAPTER 1 INTRODUCTION 1 Water Bodies and Hydrology 2 Water Pollution Problems 4 Improving Water Quality 5 The Stormwater Treatment Train 5 Using BMPs to Improve Water Quality 6 CHAPTER 2 STORMWATER MANAGEMENT PLANNING PROCESS 9 Step 1: Identify and Analyze Site Conditions 9 Context 9 The Development Site 10 Step 2: Prepare a Preliminary Stormwater Management Plan 12 Runoff Rate and Volume 12 Likely Pollutants and Treatment Objectives 14 Schematic Site Water Quality Impact Study 14 Step 3: Prepare a Final Stormwater Management Plan 15 Water Quality Impact Study 15 Integrating BMPs Into the Planning Process 18 Water Quality Boulevard 19 Water Quality Road 20 Environmentally Sensitive Parking Lot 21 Water Quality Residential Lot 23 Water Quality Commercial Property 23 Benefi ts to Development 24 CHAPTER 3 CONSTRUCTION PHASE 25 Stormwater Pollution Prevention Plan 25 Site Clearing BMPs 26 Erosion Control BMPs 26 Sediment Control BMPs 27 BMPs to Control Water Runoff 27 Good Housekeeping Measures 28 CHAPTER 4 SITE MANAGEMENT AND MAINTENANCE 29 Maintaining the Treatment Train 29 Good Housekeeping Measures 29 EAST BATON ROUGE MASTER DEVELOPMENT PROGRAM CHAPTER 5 STORMWATER BMPs 31 Detention and Retention Systems 32 Dry Pond 32 Wet Pond 32 Pond Edge with Bulkhead 33 Pervious Paving with Manufactured Subsurface Storage 34 Infi ltration Systems 35 Pervious Paving 35 Pervious Paving with Aggregate Subsurface Storage 36 Infi ltration Device 37 Cistern 37 Filtration Systems 38 Bioswale 38 Stormwater Planter 1 Permeable 39 Stormwater Planter 2 impermeable 40 Sand Filter Basin 41 Catch Basin Insert 42 Water Quality Wetlands 43 Rain Garden 43 Green Roof 44 CHAPTER 6 RESOURCES FOR STORMWATER BMPs 47 Websites 47 City Parish Contacts 47 Reference Books 48 CHAPTER 7 GLOSSARY OF TERMS 53 CHAPTER I INTRODUCTION INTRODUCTION necessary to protect the watersheds INTRODUCTION within and around the City of Baton This document summarizes the work Rouge-Parish of East Baton Rouge from that was completed by the Louisiana the adverse impacts of nonpoint source Department of Environmental Quality pollution. (LDEQ), the City-Parish Planning Commission (CPPC), and Louisiana Stormwater management (SWM) is a State University’s School of the Coast diverse issue that concerns practically and Environment, in association with everyone, including engineers, the grant entitled, “Mitigating Nonpoint landscape architects, architects, Source Pollution in Urban Watersheds planners, developers, environmentalists, with Spatial Modeling, Best Management public offi cials, civic groups, realtors, Practices for Wetlands and Community homeowners, and renters. They can Outreach.” all use this information as practical guidance in site planning and design, The sources of water pollution are control of pollutant sources, and characterized as either nonpoint or stormwater treatment. The result will point source pollution. Point source mitigate urban runoff pollution and pollution can be traced to a specifi c spot improve stormwater management as the source, such as pollution from for new development projects or industrial waste or sewage treatment redevelopments of underutilized land. plants. Nonpoint Source (NPS) Pollution originates from many diffused sources The ways in which land is developed that deposit pollutants on the ground. and used is the most obvious and Pollution occurs when rain, snowmelt infl uential contributor to urban runoff. or irrigation drains over (runoff) and There is a direct correlation between through (fi ltration) the ground. As the human activities and regional patterns runoff moves, it picks up and carries of wet and dry pollutants entering the away natural and manmade pollutants, urban landscape. Undeveloped land ultimately depositing them into lakes, in its natural state is very effective in rivers, wetlands, coastal waters, and minimizing stormwater runoff and water even aquifers (underground sources pollution through several processes. A watershed of drinking water). This Master is the specifi c Development Program Manual will The quantity of runoff is minimized land area that guide the implementation of measures compared to developed land because drains water into a river system or other body of water. Figure 1: Hydrologic Cycle, Natural Environment 1 EAST BATON ROUGE MASTER DEVELOPMENT PROGRAM trees, shrubs, grasses and other plants watersheds. Best Management Practices utilize the water, taking it in through (BMPs) can be applied to individual leaves and roots. Plant leaves dissipate developments within these watersheds. the energy of raindrops, which reduces The scale of the new sub-watershed is a impact on the ground and, in turn, compromise between development and reduces erosion. Rainwater and runoff the water quality assessment made by are also slowed by plants, providing regulatory authorities (G. Paul Kemp, more time for evapotranspiration and 2005 Annual Report). infi ltration processes to occur. Finally, water that does become runoff is Using existing Light Detection And fi ltered and treated by plants, resulting Ranging (LIDAR) Data, EBRP was in cleaner water entering lakes and divided into fi ve geologically defi ned streams. terraces that change in elevation from Our water south to north beginning with the bodies must Typical urban development practices in Manchac Alluvium, continuing through be fi shable and Louisiana often begin with completely Terraces 1, 2 and 3, and fi nally to the swimmable. clearing the land, leaving it unprotected. Mississippi River Drainage terrace. Construction activities, particularly Elevation thresholds were derived for earthmoving and grading work, increase each area to separate source (runoff soil erosion, runoff, and water pollution. producer) from sink (runoff receiver) Projects are typically designed and built zones. The sink zones have historically with signifi cantly increased impervious experienced occasional backwater surfaces, such as roofs, roads, and fl ooding (Kemp et al. 2005), and make up parking areas. The result creates higher approximately 18 percent of the Parish peak fl ows which in turn increases (Figure 2). pollutant runoff and pollution deposition into lakes and streams. This typical East Baton Rouge Parish is bordered urbanized condition also contributes on three sides by natural waterways. to backwater fl ooding in Louisiana. The Mississippi River is the western Backwater fl ooding is upstream fl ooding boundary and receives a limited amount caused by downstream conditions such of drainage from the northeastern part as channel restrictions or high fl ow in a of the parish and downtown Baton downstream confl uence of waterways. Rouge. Bayou Manchac, formerly a The water has no place toward which to tributary of the Mississippi River, is the drain, so it backs up and fl oods the areas southern boundary and drains much upstream. of the southern part of the parish. The Amite River fl ows north to south along Water Bodies and Hydrology the eastern boundary and receives all the water from Bayou Manchac and the The LDEQ and the U.S. Environmental Amite River watershed. The northern Protection Agency (EPA) have assessed boundary is drawn along a latitudinal water quality for ten hydrologic sub- line (roughly 30.7o north latitude) and basins in East Baton Rouge Parish is not defi ned by a drainage feature. (EBRP). Louisiana State University’s Within the parish the average rainfall (LSU) School of the Coast and is 77.64 inches per year, which also Environment Research Team divided the signifi cantly contributes to the Baton LDEQ sub-basins into smaller sub- Rouge waterways. 2 INTRODUCTION According to the 1996 National Water Quality Inventory, stormwater runoff is a Amite River leading source of water pollution. Mississippi River Bayou Manchac Figure 2: Watersheds and Elevation in East Baton Rouge Parish Table 1: East Baton Rouge Parish Terrace Elevation Thresholds 3 EAST BATON ROUGE MASTER DEVELOPMENT PROGRAM Water Pollution Problems of each pollutant into each segment, with the purpose of improving water quality. According to the 1996 National Water Quality Inventory, stormwater runoff Pollutants generated by human activities, is a leading source of water pollution. deposited over exterior surfaces, such A Total Maximum Daily Load (TMDL) as rooftops, parking lots, streets, patios, establishes the maximum amount of a lawns