LAKE COUNTY
STORMWATER MANAGEMENT NEEDS ASSESSMENT
FINAL
Prepared by Camp Dresser & McKee Inc.
MAY 1991
environmental engineers, scientists, M.. planners, & rnonogernent cmsultonts c-. LAKE COUNTY, FLORIDA
STORMWATER MANAGEMENT NEEDS ASSESSMENT
FINAL REPORT
CAMP DRESSER & McKEE INC.
MAY 1991 CONTENTS
Section Page 1.0 INTRODUCTION 1-1 1.1 Background 1.2 Report Purposes and Contents 2.0 DATA SOURCES 2-1 Lake County Neighboring Counties Participating Cities and Towns Non-Participating Cities Lake County Water Authority (LCtJA) United States Geological Survey (USGS) United States Army Corps of Engineers (USACOE) United States Department of Agriculture Soil Conservation Service (USDA-SCS) Federal Emergency Management Agency (Fm) National Climatic Data Center (NCDC) St. Johns River Water Management District (SJRWMD) Southwest Florida Water Management District (SWFWMD) Florida Department of Environmental Regulation (FDER) Florida Department of Transportation (FDOT) Florida Department of Community Affairs (DCA) 3.0 HYDR0UX;IC AND HYDRAULIC BACKGROUND 3-1 Major Basins 3.1.1 Oklawaha River 3.1.2 Withlacoochee River 3.1.3 Wekiva River 3.1.4 Kissimmee River 3.1.5 St. Johns River Hydrologic Boundaries Topography Aerial Photography Soils Rainfall Stage and Discharge Floodplains and Floodways Land Use and Growth Trends Regional Aquifer Characteristics Inventory of Major Stomter Conveyance Structures 4.0 STORMWATER MANAGEMENT REGULATIONS 4-1 4.1 Lake County 4.2 Cities and Towns 4.3 Federal and State CONTENTS (contents)
Section Page 5.0 WATER QUALITY 5-1 5.1 General 5.2 Best Management Practices (BMPs) 5.2.1 Structural BMP Alternatives 5.2.2 Comparison of Structural BMPs 5.2.3 Design Criteria for Preferred Structural BMPS 5.2.4 Pollutant Removal Efficiencies 5.3 Regional vs. Onsite Deployment of Structural BMPs 5.4 Water Quality Evaluations 5.4.1 Existing Lake County Monitoring 5.4.2 Trophic State Index 5.4.3 Stormwater Pollutant Loadings 5.4.4 Failing Septic Tank Impacts 5.4.5 Average Annual Non-Point Pollution Loads 5.5 Summary 6.0 PROBLEM AREAS 6.1 General 6.1.1 Water Quantity (Flooding) 6.1.2 Water Quality 6.2 Problem Area Identification and Evaluations 6.2.1 Water Quantity Problem Areas 6.2.2 Water Quality Problem Areas 6.2.3 Non-Problem Facilities 7.0 COMPUTER MODEL COMPARISONS 7.1 Water Quantity Models 7.1.1 Water Quantity Model Comparison Items 7.1.2 Available Water Quantity Models 7.1.3 Water Quantity Model Recommendations 7.2 Water Quality Models 8.0 LEVELS OF SEKVICE 8.1 Water Quantity 8.2 Water Quality 8.3 Summary 8.4 Prioritization CONTENTS (continued)
Section Xe
9.1 on-Structural Improvements 9.1.1 Goals, Objectives, and Policies 9.1.2 Stormwater Management Regulations and Ordinances 9.1.3 Maintenance Practices 9.2 Structural Improvements 9.2.1 Problem Area Improvements 9.2.2 Unknown Problem Area Improvements 9.2.3 Additional Stormwater Management Program Needs 9.3 Prioritization 9.4 Additional Program Needs APPENDICES APPENDIX A - LAKE COUNTY'S STORMKATER SUB-ELEMENT, CHAPTER V1-C, OF THE COUNTY'S COMPREHENSIVE PLAN APPENDIX B - DATA o Hydrologic Boundary Map o Stormwater Facility Inventory by SubBasin o Soils by Sub-Basin o Land Use by Sub-Basin APPENDIX C - DRAFT STORMNRTER MANAG- ORDINANCE (Provided to Lake County under separate cover)
iii LIST OF TABLES
Table Page Design Storms Recommendations for the Major Basins Rainfall Summary for Lake County Area, Florida Estimated Water Quality Based on Historic Storms USGS Lake Gages in the Study Area USGS Stream Gages in the Study Area USGS Well Gages in the Study Area Imperviousness by Land Use Category CDM vs. County Land Use Categories Monitored Wet Detention Basin Efficiencies Total-P and Dissolved P Summary Summary of Lake Water Quality Monitoring Data Sumrnary of Lake County Trophic State Index Analysis Summary of Lake County Land Use and Hydrological Soils Group Comparison of Average Annual Total-P Loading Factors for Urban Land Uses: Occoquan Watershed Monitoring Study vs. NURP National Statistics Summary of Non-Point Pollution Loading Factors by Hydrologic Soils Group Event Mean Concentrations for the Orlando Metro Areawide Water Quality Study (ECFRPC, 1978) Event Mean Concentrations and Impervious Percentages for the Tampa Bay Study (CDM, 1984) Event Mean Concentrations and Impervious Percentages for the Manatee County Southeast Area Study (CDM, 1985) Water Quantity Problem Areas by Sub-Basin Water Quality Problem Areas by Sub-Basin Water Quantity Model Sceening Matrix Recommended Maintenance Frequencies by Facility Type Annual Maintenance Costs Problem Area Summary Conceptual Probable Costs for Retrofit Treatment Facilities Lake County Stomwater Master Plan Basin Studies Cost Estimate Priorities for Stormwater Master Planning by Basin Stomwater Management Program Probable Cost Summary LIST OF FIGURES
Following Fiaure Page Major Basins Detailed Topographic Coverage Generalized SCS Soils Mean Annual, 24-Hour Maximum Rainfall for Northeast Florida, Inches 10-Year, 24-Hour Maximum Rainfall for Northeast Florida, Inches 25-Year, 24-Hour Maximum Rainfall for Northeast Florida, Inches 100-Year, 24-Hour Maximum Rainfall for Northeast Florida, Inches 25-Year, 96-Hour Maximum Rainfall for Northeast Florida, Inches Rainfall Gages Adapted from SJRWMD TP-88 USGS Lake Gages USGS Stream Gages High Growth Areas Groundwater Characteristics Wet Detention Basin Settling Curves Onsite vs. Regional BMPs Typical Multi-Purpose Facility Typical Swale Mean Concentration 1985-1990: Total-P Mean Concentration 1985-1990: Total-N Mean Concentration 1985-1990: Secchi Mean Concentration 1985-1990: CHL-A Average Annual Load: Total-P Average Annual Load: Total-N Average Annual Load: Lead Average Annual Load: Zinc Average Annual "Per Acre" Load: Total-P Average Annual "Per Acre" Load: Total-N Average Annual "Per Acre" Load: Lead Average Annual "Per Acre" Load: Zinc Water Quantity Problem Areas by Sub-Basin Water Quality Problem Areas by Sub-Basin Water Quantity Levels of Service Water Quality Levels of Service 1.0 INTRODUCTION
1.1 BACKGROUND
In May 1990, Lake County initiated a phased Stormwater Management Program (SWMP) to manage surface and groundwater resources in the County. Camp Dresser & McKee Inc. was selected to perform services related to this program. The main purposes of the County's overall Stormwater Management Program are identified as the following:
1. Build a stormwater management system data-base and information management system which will inventory, locate and describe existing stormwater management systems, hydrologic basins, and other related hydrologic parameters in Lake County.
2. Evaluate existing stormwater management system ordinances, maintenance conditions, and practices.
3. Develop and apply a stormwater management computer model to simulate stormwater runoff of various frequencies under existing and future planned land use conditions.
4. Analyze the capability of the existing stormwater system to accommodate present and future stormwater flows.
5. Assess the magnitude of existing and anticipated future stormwater problems within the County and prioritize those problems relative to their need for attention.
6. Establish desired level of service criteria for the various components of the stormwater management system.
7. Evaluate alternative management plans to meet the desired service level based on existing and future anticipated deficiencies identified through data collection and modeling. 8. Develop cost estimates for needed improvements.
9. Develop a Stormwater Management System Capital Improvement Plan based on identified system improvement needs and a prioritized implementation schedule.
10. Identify and, if required, develop alternative funding methodologies, including a stormwater utility, necessary to fund stormwater management system capital improvements, operations and maintenance and administration.
11. Meet the planning requirements of the Stormwater Sub-Element of Chapter 95-5, Florida Administrative Code (FAC).
1.2 REPORT PURPOSES AND CONTENTS
This report presents results from Tasks 1 and 2 of the SWMP: Data Collection and Preliminary Needs Assessment. Within these two tasks, the foundation for completing the 11 overall purposes of the SWMP has been formed. For this report, stormwater-related data were collected, evaluated for adequacy and quality, and utilized to establish levels of detail and priorities for subsequent SWMP tasks. In addition, conceptual Capital Improvement Program (CIP) probable cost estimates were made for facilities to mitigate known stormwater quantity problems, and to provide for the treatment of stormwater in areas where such facilities do not exist. This report also presents the recommended levels of service and detail to meet the requirements of Chapter 95-5, FAC, and the additional future tasks which will be required for Lake County to complete the overall Stormwater Management Program objectives. 2.0 DATA SOURCES
Presented below is a summary of the numerous entities and agencies which retain the stomter data and previous reports pertinent to the Lake County stomter management system. These entities and agencies were contacted to obtain or reference existing data and previous reports. The pertinent data and reports are referenced by the respective entity which retains them.
LAKE COUNTY
Departments within the Lake County government infrastructure were contacted to evaluate and document the County's stormwater management resources and existing data and reports.
The information provided by Lake County personnel is presented below:
o Maps showing municipality boundaries, roadways, lakes, canals, and bridges at scales of lV=1 mile and 1"=2 miles;
o Map showing the delineation of maintenance district boundaries at a scale of 1"=1 mile;
o The Lake County Township Book (34 maps) published in 1976 and revised in 1990, showing municipality boundaries, roadways, lakes, and canals at a scale of 1"=200OP;
o The Lake County Drainage Atlas developed as part of the Lake County Comprehensive Plan Drainage Element published in 1976. Consisting of 29 USGS 7.5 minute quadrangle maps with overlays at a scale of 1"=2000t,the Atlas shows municipality and hydrologic basin boundaries, existing facilities, flood prone areas, roadways, lakes, canals, and topographic features; o The State of Florida Department of Transportation (FDOT) General Highway Maps for Lake County published in May, 1979. Municipality, boundaries, roadways, lakes, and canals are shown at a scale of 1"=2 miles;
o The Lake County subdivision regulations as amended in 1988. This document establishes design standards for the development of subdivisions;
o The Lake County Comprehensive Plan published in 1980 was obtained from the Lake County Planning Department;
o Identification of stormwater-related problem areas in the County;
o Septic Tank Water Quality Impact Study, July 1982, Lake County Department of Pollution Control;
o Water quality data in digital form for sampling stations and map showing locations was obtained from the Lake County Department of Pollution Control;
o Residential and Seasonal Population Estimates and Projections for Lake County, Florida, 1980-2005, Lake County Planning Department, December, 1989;
o Index to Lakes by Name and Location, Lake County, Florida, Lake County Planning Department; and
o Index to Class I11 - A Lakes by Name and Location, Lake County, Florida, Lake County Planning Department.
2.2 NEIGHBORING COUNTIES
The Counties of Marion, Orange, Osceola, Polk, Seminole, Sumter, and Volusia share Lake County's border. Personnel were contacted in each of these counties to ascertain pertinent stormwater data and reports related to Lake County's stormwater management system. Some counties are currently in the process of formulating their own stormwater programs and/or did not have pertinent data and thus could not provide the requested information. The information which was received from the neighboring counties is presented below.
o Data for Drainage Analysis Units (DAU1s)1 and 2 (the Palatlakaha and Withlacoochee Rivers, respectively) from the Polk County Surface Water Management District were obtained. The DAU1s contain pervious curve numbers for each sub-basin, and minor basin as well as sub-basin location maps, land cover area data, percent impervious surface, and FEMA 100 year floodplain maps.
o There are a few drainage complaints throughout the Wekiva River Basin which are maintenance related, or due to lack of a drainage system, resulting in localized flooding in Seminole County. Construction plans, drainage calculations for developments, and topographic-aerials, are available throughout the Seminole County portion of this basin, but these data do not appear to affect systems in Lake County.
As Lake County progresses with its stormwater management program further coordination with the neighboring counties will be required to assure that each county's stormwater management program is properly integrated with Lake County's.
2.3 PARTICIPATING CITIES AND TOWNS
The following cities and towns are contributing to the funding of the Lake County Stomwater Management Program:
o Astatula o Fruitland Park o Groveland o Howey-in-the-Hills o Lady Lake o Mascotte o Minneola o Monteverde o Umatilla
Personnel within each of the cities and towns were contacted to ascertain the merits of their existing stormwater management ordinances, the frequency of maintenance operations for their stormwater facilities, the availability of pertinent stormwater data and reports, and the identification of stormwater problems. A summary of this information provided by the participating cities and towns is presented below.
STORMWATER MANAGEMENT ORDINANCES
The information pertaining to the Stormwater Management Ordinances for the cities and towns of Lake County is presented in Section 4.0 of this report.
STORMWATER FACILITIES MAINTENANCE
Personnel from each city and town indicated that they have no set stormwater facility maintenance practices. Maintenance is provided within each city and town by city or town maintenance crews, along with county maintenance crews, on an as-needed basis. Thus maintenance is usually performed in a reactionary mode of operation (i.e., to alleviate a known problem) versus a preventive mode.
AVAILABLE DATA AND REPORTS
Personnel from each city and town reported that they did not have records pertinent for stormwater hydrology, hydraulic, and water quality data. The personnel suggested that Lake County, the Lake County Water Authority (LCWA), or the state and federal agencies be contacted for such information. PROBLEM AREA IDENTIFICATION
Problem areas were identified within the Cities of Groveland, Mascotte, Minneola, and Umatilla. No problem areas were identified within the Towns of Lake County. Further discussion of the problem areas is presented in Section 6.0 of this report.
2.4 NON-PARTICIPATING CITIES
Five other cities located within Lake County, which are not participating with the funding of the Lake County Stomwater Management Project were contacted for the same data requested of the participating cities and towns. A copy of the subdivision ordinances were obtained during follow-up visits by CDM. A summary of the stomwater management design standards contained in the subdivision ordinances is presented in Section 4.0 of this report. The responses to this request for information are presented below for each city.
CITY OF CLEZMONT
Several attempts were made to contact City of Clermont personnel regarding the forwarding of pertinent hydrologic, hydraulic, water quality, problem area, stomwater maintenance, and stormwater ordinance. However, the requested data has not been forwarded by the City. Coordination with the City of Clermont will be required as the County proceeds with future phases of its Stomter Management Program.
CITY OF EUSTIS
Several attempts were made to contact City of Eustis personnel regarding the forwarding of pertinent hydrologic, hydraulic, water quality, problem area, stomwater maintenance, and stormwater ordinance data. The City's civil engineering consultant forwarded a map of the City showing problem area locations to CDM. Coordination with the City of Eustis will be required as the County proceeds with future phases of its Stormwater Management Program. CITY OF LEESBURG
City personnel indicated that much of the information requested (basic hydrologic, hydraulic, and water quality data for the City; water quantity and quality problem area records; and maintenance records/practices for stormwater facilities) has not been documented by the City or it is available at the County level. A map indicating areas of known flooding problems was forwarded. There are no written records of water quality data available. A cow of relevant design criteria utilized since the early 1980's was also included. The City referred to the FDER, SJRWMI), and LCWA for water quality data. The City was conducting their first drainage study for a small basin in the northwest area of the City. This study is nearing completion.
CITY OF MOUNT DORA
The City of Mount Dora is currently beginning its own stormwater program. Thus the requested data is not presently available. Information acquired during the development of the City's stormwater plan will be available for use in developing the future phases of the Lake County Stormwater Management Program.
CITY OF TAVARES
Several attempts were made to contact City of Tavares personnel regarding the forwarding of pertinent hydrologic, hydraulic, water quality, problem area, stormwater maintenance, and stormter ordinance data. However, the requested data has not been forwarded by the City. Coordination with the City of Tavares will be required as the County proceeds with future phases of its Stormwater Management Program.
2.5 LAKE COUNTY WATER AUTHORITY ( LCWA)
Recognizing the vital role that healthy lakes and rivers play in the economy and quality of life in Lake County, the Florida Legislature established in 1953, the Lake County Water Authority (LCWA), formally known as the Oklawaha Basin Recreation and Water Conservation and Control ~uthorityof Lake County.
The following publications and data were provided by LCWA:
o Digital rainfall data for the Eustis, Deland, Sanford, Bushnell, Inverness, Orlando, Ocala, and Lake Alfred gages;
o Copies of the Lake County Drainage Atlas hydrologic boundaries (at 1:24,000 and 1:100,000 scales);
o State plane coordinate references for USGS 1:24,000 quadrangle corner points for use in AutoCAD mapping;
o Key map for the LCWA topographic aerial maps. These are 1"=200t scale, 1-foot contour maps with 1987 photogrammetry. These maps will be acquired as necessary for the master plan;
o Converted 1986 land use from ERRAS format (from ECFRPC) into ARCH-INFO fo-t;
o Identification of specific problem areas in the County such as Wolf Branch sink; and
o updates on the ongoing Upper Palatlakaha River Study by Environmental Science and Engineering (ESE).
The following stormwater-related publications are available in the LCMAfs library:
o Water and Related Land Resources Florida West Coast Tributaries, United States Department of Agriculture, in cooperation with the Division of Water Resources and Conservation Florida State Board of Conservation, 1965; o The Green Swamp Project Executive Report Resource Management Department, Southwest Florida Water Management District, January 1985; o Hydrology of Lake County, Florida, U.S. Geological Survey Water Resources Investigation 76-72, August 1976; o Work Plan for Palatlakaha River Watershed - Lake County, Florida, Oklawaha Basin Recreation and Water Conservation and Control Authority, Lake Soil Conservation District, Assisted by United States Department of Agriculture, Soil Conservation Survey, August 1965; o Information Circular No. 40 Mapo Showirig Depths of Selected Lakes in Florida, Prepared by U.S. Geological Survey in cooperation with the Trustees of the Internal Improvement Fund of the State of Florida, Tallahassee, 1964; o Fish Management Annual Progress Report, Florida Game and Fresh Water Fish Commission Central Region, 1986-89; o Water Withdrawals, Use, and Trends in the SJRWMD, St. Johns River Water Management District, August 1988; o Map Showing Depths of Selected Lakes in Florida, U.S. Geological Survey in cooperation with the Trustees of the Internal Improvement Fund of the State of Florida, 1964; o Fish Management Annual Progress Report, Florida Game and Fresh Water Fish Commission, Central Region, 1986 - 1989; o Water Withdrawals, Use, and Trends in the SJRWm, St. Johns River Water Management District, Palatka, Florida, 1986; o List of Publications, Florida Department of Natural Resources, Division of Resource Management, Bureau of Geology, Tallahassee, Florida, 1984; o Proposed Scope of Work for the Lake Apopka Pilot Project, St. Johns River Water Management District, February 25, 1986; o Rainfall Analysis for Northeast Florida - Part I: 24-Hour to 10-Day Maximum Rainfall Data, St. Johns River Water Management District, July 1986; o Save Our Rivers Five-Year Land Acquisition and Management Plan, St. Johns River Water Management District, Palatka, Florida, December 13, 1988; o Florida: Groundwater Resources National Water Summary, U.S. Geological Survey; o Orlando Metropolitan 208 Study: Stomwater Management Practices Evaluations, East Central Florida Regional Planning Council, July 1979; o The Green Swamp Project: Environmental Report, Southwest Florida Water Management District, Resource Management Dept., January 1985; o The Green Swamp Project: Economic Report, Southwest Florida Water Management District, September 1984; o Inspection Report Oklawaha Basin Recreation and Water Conservation and Control Authority, Gee & Jenson, Consulting Engineers, Inc., September 1974; o Draft Report for the Palatlakaha River Basin, Florida Draft, Volume 1, Seaburn and Robertson, Inc., Water Resources Consultants, January 1981; o Hydrologic Data from A 2,000-Foot Deep Core Hole at Polk City, Green Swamp Area, Central Florida, U.S. Geological Survey Water Resources Investigations Report 84-4257, Prepared in cooperation with City of Cape Coral, Tallahassee, Florida, 1986; o Summary of Findings on Water Management Needs of Southwest Florida, Florida Department of Water Resources, Tallahassee, Florida, May 1961; o Floodplain Study of the Hicks, Ditch Basin in Lake County, Florida, St. Johns River Water Management District, Palatka, Florida, 1990; o Vertical Recovery Sheets (Survey Control Data) Lake County, Florida, Auman, Dray, West and Associates, Orlando, Florida; o Revised Available Data Report Palatlakaha River Basin, Florida Volume 6 U.S. Army Corps of Engineers, Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, June 1981 ; o Evaluation of Water Resources Palatlakaha River Basin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, June 1981; o Available Data Report for the Palatlakaha River Basin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, December 1980; o Draft Report for the Palatlakaha River Basin, Florida Volume 2 U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, January 1981; o Evaluation of Water Resources - Phase I1 Palatlakaha River Basin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, November 1982; o Mathematical Simulations of the Little Creek Watershed, R.D. Ghioto Water Resources and Civil Engineering, October 1982; o Engineering Report on Inland Waterways of Florida for Interim Committee on Inland Waterways of the 1951 Legislature, Gee & Jenson, Consulting Engineers, Inc., February 4, 1953; o Hydrologic and Hydraulic Study of the Turkey Lake Watershed, Ghioto, Singhofen & Associates, Inc., Water Resources and Civil Engineering Consultants, July 17, 1984; o The Canal Authority of the State of Florida Annual Report, Principal Office - Jacksonville, Florida, October 1964; o Planning Unit Appendix St. Johns River Basin and Intervening Coastal Areas in Florida, U.S. Department of Agriculture Soil Conservation Service, Gainesville, Florida, 1969; o A Study of Water Management Alternatives for the Middle Oklawaha River Basin, Southwest Florida Water Management District, December 1976 ; o Report for St. Johns River Basin and Intervening Coastal Areas Florida, U.S. Department of Agriculture Soil Conservation Service, Gainesville, Florida, 1969; o Report to the Governor, Florida Rivers Study Committee, January 31, 1985; o First Biennial Report of the Florida Department of Water Resources for the Period October 15, 1957 through December 31, 1958, Tallahassee, Florida, 1959; o Second Biennial Report, 1959-1960 Florida Department of Water Resources January 1, 1959 - December 31, 1960, Tallahassee, Florida, 1961; o Catalog of Information on Water Data Index to Areal Investigation and Miscellaneous Water Data Activities, U.S. Department of the Interior, Geological Survey Office of Water Data Coordination,
o 1980 Annual Report, Lake County Department of Pollution Control Tavares, Florida, January 1981; o Hydrologic Records Program for 1979 and 1978 Fiscal Years in cooperation with Lake County, U.S. Geological Survey, May 25, 1977 ; o A Report of the Water Quality of A Portion of the South Lake County Chain of Lakes, Lake County, Florida, Florida State Board of Health Bureau of Sanitary Engineering, Jacksonville, Florida, 1966 ;
o Preliminary Report on Flood Control Problems Withlacoochee River, Florida for Department of Water Resources State of Florida, Maurice H. Come11 & Associates, Inc., Consulting Engineers, March 1961 ;
o Wekiva River Aquatic Preserve Management Plan Draft The Department of Natural Resources, Bureau of Land and Aquatic Resource Management, Division of Recreation and Parks, June 1987;
o Re~0rton Flood of March 15-18.1960 U.S. Armv Enaineer District, Jacksonville, Office of the District Engineer Corps of Engineers Jacksonville, Florida, April 1960;
o Comprehensive Drainage Plan Lake County, Florida Phase I1 Hydrologic Evaluation of Basin Segments and Sub-segments, Lake County Planning Department, October 4, 1978; o Florida Lakes. Part I A Studv of the Hiah Water Lines of Some Florida Lakes Part 2 A Tentative Classification of Lake Shorelines, Division of Water Resources, Florida Board of Conservation Tallahassee, Florida, 1967;
o Application for Funding Johns Lake Orangebake Counties, Florida under EPA Clean Lakes Program 40 CFR 35, Subpart H, Johns Lake Improvement Association Killarney, Florida, February 22, 1990;
, . o Lake County Drainage Atlas, Newman Consulting Engineers, Inc., Leesburg, Florida, 1976;
o Hicks Ditch - Horizontal and Vertical Controls Palatlakaha - Horizontal and Vertical Controls River Aerial Map-, St. Johns River Water Management District, 1990;
o ~lood~azard Study Black Water Creek and Tributaries Lake County, Florida, SCS, August 1984;
o Comprehensive Report on Four River Basin, Florida, Part I, Part -11, U.S. Army Corps of Engineers, November 30, 1961;
o Comprehensive Report on Four River Basin, Florida, U.S. Army Corps of Engineers, November 30, 1961;
o Four River Basins Project Florida, Plan of Study, U.S. Army Corps of Engineers, 1975;
o Oklawaha River Basin Flood Damage Study for 1959, High Water, Florida Department of Water Resources, July 1, 1959;
o Review Report on Oklawaha River Basin, A Survey of Potential Benefits from Water Control in the Oklawaha River Basin, Water Resources and Florida Department of Water Resources and Gee & Jenson, Consulting Engineers, Inc., November 1961; o Review Report of Oklawaha River Basin, Part I, Chittachattee Channel, Florida Department of Water Resources and Gee & Jenson, Consulting Engineers, Inc., January 1961; o Review Report of Oklawaha River Basin, Part 11, Future Flood Control Program, Florida Department of Water Resources and Gee & Jenson, Consulting Engineers, Inc., April 1961; o Preliminary Investigation and Report on Proposed Impoundment Areas in Southeast Green Swamp, Polk County, Florida, Florida Department of Water Resources - Lamar Johnson, February 1961; o Water Resources of Lake County, Florida Department of Water Resources, 1960; o Florida Lakes, Part 111, Gazetteer, Division of Water Resources, Florida Board of Conservation, 1969; o Waterways - Comprehensive Regional Plan Series, East Central Florida Regional Planning Council, September 1967; o Upper Oklawaha River Basin, East Central Florida Regional Planning Council, February 1973; o Florida Water and Related Land Resources, St. Johns River Basin, Florida Department of Natural Resources,.1970; o Report on Water Control and Navigation, Lake Apopka Recreation & Water Conservation & Control Authority, April 1954; o Design Report, Part IV, Phase I, Palatlakaha River Watershed, Oklawaha Basin Recreation & Water Conservation & Control Authority, Gee & Jenson, Consulting Engineers, Inc., August 1967; o Soil Survey of Lake County Area, Florida, U.S. Department of Agriculture, Soil Conservation Service, April 1975; o Final Environmental Statement for Palatlakaha River Watershed, U.S. Department of Agriculture, Soil Conservation Service, April 1973; o Hydrologic Records for Lake County, 1970-71, U.S. Geological Survey, 1972; o Hydrologic Records for Lake County, 1971-72, U.S. Geological Survey, 1973; o Hydrologic Records for Lake County, 1972-73, U.S. Geological Survey, 1974; o Hydrologic Records for Lake County, 1973-74, U.S. Geological Survey, 1975; o Hydrologic Records for Lake County, 1975-76, U.S. Geological Survey, 1977; o Hydrologic Records for Lake County, 1976-77, U.S. Geological Survey, 1978; o Hydrologic Records for Lake County, 1977-78, U.S. Geological Survey, 1979; o Hydrologic Records for Lake County, 1978-79, U.S. Geological Survey, 1980; o Hydrologic Records for Lake County, 1979-80, U.S. Geological Survey, 1981; o Hydrologic Records for Lake County, 1980-81, U.S. Geological Survey, 1982; o Hydrologic Records for Lake County, 1981-82, U.S. Geological Survey, 1983; o Hydrologic Records for Lake County, 1982-83, U.S. Geological Survey, 1984; o Hydrologic Records for Lake County, 1983-84, U.S. Geological Survey, 1985; o Hydrologic Records for Lake County, 1984-85, U.S. Geological Survey, 1986; o Hydrologic Records for Lake County, 1985-86, U.S. Geological Survey, 1987; o Hydrologic Records for Lake County, 1986-87, U.S. Geological Survey, 1988; o Hydrologic Records for Lake County, 1987-88, U.S. Geological Survey, 1989; o Hydrologic Records for Lake County, 1988-89, U.S. Geological Survey, 1990; o Index to Areal Investigations and Miscellaneous Water Data Activities, U.S. Geological Survey, 1970; o Hydrologic Data Index for Florida, U.S. Geological Survey, 1966; o Index to Catalog of Information on Water Data Surface Water Stations, U.S. Geological Survey, 1972; o Catalog of Information on Water Data, U.S. Geological Survey, 1966; o Index to Catalog of Information of Water Data, Water Quality Stations, U.S. Geological Survey, 1975;
o Water Resources Data for Florida, Volume 2, pp. 1-770, Volume 2, pp. 771-1451, U.S. Geological Survey, 1975;
o Floodplain Information, Wekiva River - Seminole, Orange, and Lake Counties, Florida, U.S. Army Corps of Engineers Jacksonville, Florida District, September 1974;
o Floodplain Information, St. Johns River and Lake Beresford, Volusia, and Lake Counties, Florida, U.S. Army Corps of Engineers Jacksonville, Florida District, September 1974;
o Florida Rivers Assessment, Department of Natural Resources, December 1989.
2.6 UNITED STATES GEOLOGICAL SUEWEY (USGS)
The USGS is the water resources agency within the United States Department of the Interior (DOI). The USGS has provided data ranging from field-measured values of stormwater stages to special studies on best management practices for pollutant removal. For this study, CDM contacted the Orlando, Florida USGS office to obtain data relative to the study area. The following paragraphs highlight the data obtained:
o Hydrology of Lake County, Florida, Water Resources Investigation 76-72, 1976 - The purpose of this publication was to inventory and appraise the water resources of Lake County and to provide part of the hydrologic information necessary for coordinated development of the resources of the County;
o Geohydrologic Reconnaissance of Drainage Wells in ~lorida,Water Resources Investigations Report 84-4021, 1984 - The general purpose and scope of this investigation was to conduct a statewide geohydrological appraisal of drainage wells. This report presents results of investigation from October, 1978 to April, 1982, for Floridan Aquifer drainage wells, Biscayne Aquifer drainage wells, and interaquifer connector wells;
o uSGS 1:24,000 and 1:100,000 topographic maps for the study area; and
o Surface and Drainage Areas of Selected Lakes in Florida, 1965, USGS Water Resources Division, Florida District.
The following applicable USGS publications are available in CDMfs library:
o ~ibliographyof U.S. Geological Survey Reports on the Water Resources of Florida, 1886-1986, Open-File Report 85-424, 1987, Fourth Edition - This publication provides a list of USGS reports for Florida.
o Hydrologic Unit Map - 1974 - This report provides a statewide system of numbering major hydrologic units;
o Roughness Characteristics of Natural Channels, 1967 - This publication provides Manning's roughness characteristics from various USGS studies nationwide;
o Water Resources Data, Florida, Water Year 1989, Volume lA Northeast Florida Surface Water - This publication provides a summary for all USGS surface water quantity and water quality gages including location, yearly and monthly statistics, periods of record, and extreme values for the periods of record. Data for crest-stage partial-record stations are also included in this report;
o Water Resources Data, Florida, Water Year 1989, Volume 1B Northeast Florida Ground Water - This report provides ground water data similar to that discussed for Volume lA; o Technique for Estimating Magnitude and Frequency of Floods on Natural - Flow Streams in Florida, 1982, Water Resources Investigations 82-4012 - This publication provides regional regression equations for use in estimating flood flows on natural streams;
o Ground-Water Hydraulics, 1979, Geological Survey Professional Paper 708 - This paper provides simplified equations and methods useful in the evaluation of groundwater flows and levels; and
o Flood Hazard Study, Black Water Creek and Tributaries, Lake County, Florida, 1981 - The objective of this study is to furnish needed technical data to local governments to assist them in identifying local flood problems and in making decisions related to land use planning and future development.
In addition to these collected data, the USGS has the following data, reports, and studies which will be useful as the County completes its SWMP:
o USGS gage data in mean daily, monthly, or water year summary form are available from the USGS or the Lake County Water Authority (LCWA) in both digital and hardcopy forms and in the form of Compact Disk (CD) Read-Only Memory (ROM) from commercial vendors.
o Hydrol:sgic Consideration in Draining Lake Apopka, A Preliminary Analysis, Open File Report, 1971;
o Hydrologic Considerations in Dewatering and Refilling Lake Carlton, Water Resources Investigations, Orange, and Lake Counties, Florida, 1977;
o A Hydrologic Description of Lake Minnehaha, Map Series 54, 1972;
o Hydrology of the Oklawaha Lakes Area of Florida, Map Series 69, 1974 ; o Potential for Downward Leakage to the Florida Aquifer, Green Swq Area, Water Resources, Central Florida Investigations. Open File Report 7.7-71, 1978;
o Lithologic and Borehole Geophysical Data, Open-File Report 78-574, Green Swamp Area, Florida, 1978;
o Long-Term Water Supply Potential, Green Swamp Area, Florida Water Resources Investigations 78-99, 1979;
o A Reconnaissance of the Qualitv of Water in Lake Dicie and West Crooked Lake Near Eustis. Florida. men File Remrt FL-69003. 1969;
o Groundwater in Lake County, Florida Map Series 44, 1971;
o Chemical and Biological Quality of Lake Dicie at Eustis, Florida with Whasis on the Effects of Storm Runoff. Water Resources Investigations 36-74, 1974;
o Hydrogeologic maps of a Flood Detention Area, Open File Report 78-460, Proposed by Southwest Florida Water Management District, Green Swamp Area, Florida, 1978; and
o Distribution and Occurrence of Total Coliform Bacteria in Floridan Aquifer Wells, Western Lake County, Florida, Water Resources Investigations Report 84-4130, 1984.
2.7 UNITED STATES ARMY CORPS OF ENGINEERS (USACOE)
The USACOE has traditionally been responsible for civil works involving water resources and navigation. Within this context, the Jacksonville District has performed studies and projects involving water resources in the study area. The following data and reports were obtained from the USACOE : o Federal Ehergency Management Agency (FEMA) Flood Insurance Study (FIS) documents in Lake County (1981), Clermont (1983), Eustis ( 1987 ) , Groveland ( 1982) , Leesburg ( 1985 ) , Mascotte ( 1983 ) , Tavares (1988), Umatilla (1989), Astatula (1982), ~adyLake (1983), Mimeola (1982), and Montverde (1982). In most cases, these documents were delivered in partial form. o Revised Available Data Report Palatlakaha River Basin, Florida Volume 6 U.S. Army Corps of Engineers, Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, June 1981; o Evaluation of Water Resources Palatlakaha River Basin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, June 1981; o Available Data Report for the Palatlakaha ~iverBasin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, December 1980; o Draft Report for the Palatlakaha River Basin, Florida Volume 2 U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, January 1981;
Evaluation of Water Resources - Phase I1 Palatlakaha River Basin, Florida U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, November 1982; o Evaluation of Water Resources Palatlakaha River Basin, Florida Volume I U.S. Army Corps of Engineers Jacksonville District, Seaburn and Robertson, Inc., Water Resources Consultants, June 1981; o Floodplain Information, Wekiva River - Seminole, Orange, and Lake Counties, Florida, U.S. Army Corps of Engineers Jacksonville, Florida District, September 1974; o Flood~lainInformation. St. Johns River and Lake Beresford. Volusia, and Lake Counties, Florida, U.S. Army Corps of Engineers Jacksonville, Florida District, September 1974;
2.8 UNITED STATES DEPARTMEW OF AGRICULTURE SOIL CONSERVATION SERVICE (USDA-SCS)
The SCS is an agency within the United States Department of Agriculture. Traditionally, their role has been to provide soil surveys and best management practice guidelines for agriculture. In recent years, the methods contained in the SCS National Engineering Handbook 4 (NEH-4) (contained in CDM1s library), have been adopted by various state, regional, and local agencies as part of the regulation of new development.
The SCS was contacted at the Lake County District office. The following paragraphs briefly discuss the SCS data and reports that were obtained:
o Soil Survey of Lake County, Florida, April 1975 - Standard SCS soil survey for Lake County. The SCS and LCWA are currently updating the Lake County Soil Survey. The updated soils information is being entered into the LCWA's Geographic Information System (GIs) using ARC-INFO. At this time, soil survey maps for specific areas can be obtained by contacting the LCWA or SCS office in Tavares. A separate soil survey is available for the Ocala National Forest. Therefore, it is not included as part of the soil survey of Lake County and was not addressed in the recent update. The survey will be used in future phases of the Stomter Management Program as needed.
o Other data on best management practices, many of which have been incorporated into the FDER Land Development Manual Chapter 6, 1989. FEDERAL EMERGENCY MANAGEMENT AGENCY ( Fm)
The Federal Emergency Management Agency (FEMA) establishes regulatory floodplains and floodways by the use of Flood Insurance Studies (FIS). In addition to the floodplain/floodway data, FEMA FIS reports and/or archives sometimes provide hydraulic data in digital format. Hence, FEMA was contacted in order to obtain these data as well as available hydrologic data for the study area.
2.10 NATIONAL CLIMATIC DATA CENTER (NCDC)
The National Climatic Data Center (NCDC) collects and maintains various types of climatological data. Precipitation data in digital format were obtained for the Lisbon and Clermont Stations.
2.11 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT (SJRWMD)
The SJRWMD was officially formed in 1972 by the State Legislature as part of Chapter 373, F.S. (Florida Water Resources Act). This act provided initial taxing and permitting authority, which, along with the size of the SJRWMD boundaries, has increased over the years. Through the 1987 SWIM Act, the SJRWMD was appointed to be the local state agency in charge of designing and implementing plans and programs for the improvement and management of the entire area in the SJRWMD. The following paragraphs highlight some of the key data obtained from the SJRWMD:
o Technical Publication SJ 79-6 Upper Oklawaha River Basin Water Management Study, Part 1: Lake Griffin Region Study, 1979 - This report presents evaluations of the Lake Griffin system for large stom under the existing regulation schedule;
o Technical Publication SJ 85-4 Burrell Dam Safety Evaluation, 1985 - This report presents an evaluation of the structural capability of the dam for extreme floods; o Technical Publication SJ 89-3 Little Wekiva River Floodplain Study, 1989 - The objectives of the study were to complete a floodplain study and to develop a comprehensive water management plan for the basin. This report presents the results of the floodplain study; o Technical Publication SJ 89-5 Water Quality Assessment of the Floridan Aquifer in the Wekiva River Basin of Orange, Lake, and Seminole Counties, 1989 - The purpose of this study is to determine the present condition of water quality in the Floridan Aquifer in the Wekiva River basin; o Lake Apopka - Restoration of a Lake - Protection of a River, St. Johns River Water Management District, 1989 - This report describes the plan to improve the quality of Lake Apopka in the near future. This plan calls for restoration of the lake's floodplain marsh and increasing the marshes natural water cleansing capacity;
o Lake Apopka Restoration Progress Report and Recommendations, A Report to the Florida Legislature by the Lake Apopka Restoration Council (LARC), 1989 - The LARC, in accordance with the Lake Apopka Restoration Act, is required to provide an annual progress report to the Legislature. This publication is the fourth report to the Legislature;
o Technical Publication SJ 90-4 Annual Water Use Survey: 1987, 1990 - Water use data for 1987 were collected by the county for SJRWMD. Graphs and tables present total water use data district-wide and by category;
o Technical Publication SJ 90-7 Floodplain Study of the Hicks Ditch Basin in Lake County, Florida, 1990 - This floodplain study is the first step toward the development of a water management plan for the Hicks Ditch basin; o Technical Publication SJ 90-10 Upper St. Johns Ground Water Basin Resource Availability Inventory, 1990 - This report provides a general inventory of the water resources of the Upper St. Johns (US) groundwater basin, including hydrogeological features, recharge and discharge areas, groundwater quality, characteristics, present and projected water use, direct water reuse, and areas suitable for future water resource development; o Technical Publication SJ 90-11 Middle St. Johns Ground Water Basin Resource Availability Inventory, 1990 - This report provides a general inventory of the ground water resources of the Middle St. Johns (MSJ) groundwater basin, including hydrogeologic features, recharge and discharge areas, groundwater quality characteristics, present and projected water use, potential for direct water reuse, and areas suitable for future water resource development; o Technical Report SJ 90-12 Annual Water Use Survey: 1988, 1990 - Water use data for 1988 were collected by the county for SJRWMD. Graphs and tables present total water use for the district and water use by category; o Technical Publication SJ 88-6 Development of Site-Specific ~ypotheticalStorm Distributions, 1988 - This report provides an initial approach to developing site-specific storm distributions; o Technical Publication SJ 88-3 Rainfall Analysis for Northeast Florida Part VI: 24-Hour to 96-Hour Maximum Rainfall for Return Periods 10 Years, 25 Years, and 100 Years, 1988 - his report provides new design rainfall amounts for the various storms; o Pan evaporation data for Lisbon and Lake Alfred, Florida; o District policy Number 79-17 which describes SJRWMD procedures for data acquisition; o Lake County lakes printout; o Lake County rainfall printout;
o Lake County wells printout; and
o Photomap index of SCS Blackwater Creek Flood Hazard Study. The following SJIiWMD reports are available in CDMfs library:
o SJRWMD Management and Storage of Surface Waters (MSSW) Applicant's Handbook, 1989;
o Draft SWIM Plan for the Upper Oklawaha River Basin, 1989;
o Technical Publication SJ 86-4 Rainfall Analysis for Northeast Florida Part 11: Summary of Monthly and Annual Rainfall Data, 1986 - This report provides the summaries as indicated;
o Technical Publication SJ 86-3 Rainfall Analysis for Northeast Florida Part I: 24-Hour to 10-Day Maxirmm Rainfall Data, 1986 - This is the base or initial report for the rainfall updates in the
o Technical Publication SJ 86-2 Magnitude and Frequency of Flood Discharges in Northeast Florida, 1986 - This report provides regional regression equation approaches for northeast Florida;
Technical Publication No. SJ 85-8 Application of Landsat Data in District Water Resources ~nvestigationsand Management, 1985 - This report provides information on the SJRWMD plan to use LANDSAT for land use mapping, including experimental programs in deriving runoff parameters such as curve numbers and a wetlands inventory for Duval County;
o Technical Publication No. SJ 85-5 A Guide to SCS Runoff procedures, 1985 - This report provides standard USDA-SCS procedures and guidelines in a condensed form; o Interim Water Quality Management Plan, 1985 - This report presents an interim approach to water quality management for the District surface waters, including some specific discussion of the Lower St. Johns River; o Water Quality Monitoring Field Manual, 1983 - Water quality field guidelines for equipment, measurements and collection, handling, and quality assurance are presented; o Technical Publication SJ 83-2 St. Johns River Water Management District Current Population and Projections - 1980, 1983 - Population projections are presented by surface water/9 basin, region, and county; o Technical Publication SJ 83-6 Hydrologic and Engineering Study for Extreme Drawdm of Little Griffin - Part 1, 1983 - This publication investigates the economic and technical feasibility and impacts of drawing down the lake to improve the sportfish habitat;
o Technical Publication SJ 82-1 Frequencies of High and Low Stages for Principal Lakes in the St. Johns River Water Management District, 1982 - For different principal lakes in the District, this publication provides information on the past levels (i.e., monthly mean elevations, and high and low elevations recorded for different continuous periods) and the future expected elevations evaluated by frequency analyses; and
o Technical Publication SJ 81-1 Structural Geolouic Features and Their relations hi^ to Salt Water Intrusion in West Volusia. North Seminole, and Northeast Lake Counties, 1981 - Salt water intrusion of wells in the St. Johns River Valley between Lakes George and Monroe (northeast Lake, North Seminole and west Volusia Counties) prompted this report to evaluate impacts on local farmers and other interests. The District also has an ongoing study of the Oklawaha River Basin which is re-evaluating lake regulation schedules. This, and an accompanying socio-economic study, are not yet completed.
2.12 SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT (SWFWMD)
The SWFWMD was officially formed in 1972 by the State Legislature as part of Chapter 373, F.S. (Florida Water Resources Act). This act provided initial taxing and permitting authority, which has increased over the years. Through the 1987 SWIM Act, the SWFWMD was appointed to be the local state agency in charge of designing and implementing plans and programs for the improvement and management of the entire area in the SWFWMD. The following SWFWMD data, reports, and studies have been obtained:
o Aerial mapping index for portions of the Green Swamp basin in southwest Lake County;
o Groundwater levels from both deep and shallow monitoring wells in digital format; and
o SWFWMD Management and Storage of Surface Waters (MSSW) Permit Information Manual.
The following studies have been ordered from the District:
o Groundwater Resource Availability Inventory for Sumter County, Florida, 1987; and
o Groundwater Resource Availability Inventory for Polk County, Florida. 1987.
2.13 FLORIDA DEPARTMEIVT OF ENVIRONMENTAL REGULATION (FDER)
The State Legislature enacted Chapter 373, F.S. in 1972 (Florida Water Resources Act of 1972). The Act established and empowered the FDER to study and propose a state water use plan. Eventually, the Department received additional regulatory authority. Currently, the FDER regulates or makes comments on nearly any significant environmental permitting activity. The following FDER data and reports have been obtained:
o Copy of Interactivation and Precipitation of Urban Runoff Entering Lake Ella by Alum Injection in Stomewers;
o Florida Nonpoint Source Assessment, Volume One, Draft, 1988 - Section 319 of the 1987 Federal Clean Water Act requires all states to assess the impact of nonpoint sources of pollution on their water bodies and to develop a plan and program to abate them. To meet these requirements, the Nonpoint Source Management Section of the FDER has prepared a two volume report. Volume One contains the statewide assessment of nonpoint source impacts on surface and ground waters;
o Directory of Injection Well Facilities, Department of Environmental Regulation Groundwater Management System, August 16, 1990 - Database providing information on injection well facilities within Lake County, including those used for drainage and lake level control;
o Recommended objections used by FDER and DCA for reviewing stormwater management subelements of comprehensive plans;
o Water Oualitv and Se~ticTanks Site Assessments: St. Lucie Countv. St. Johns Countv. Lake Countv. Dixie Countv. Hernando County, and Monroe County, Florida Department of Environmental Regulation; and
The following FDER data and reports are in CDMts library:
o The Florida Land Development Manual, 1989 - This manual provides a wide range of sound development practice guidelines; and o Copy of Operational Results from the Restoration of Lake Ella. A project in which alum injection systems were used to provide chemical stormwater treatment in an urbanized area.
o Copies of Environmental Exchange Point Newsletters, Office of Planning and Research - This publication is produced to help prepare local government comprehensive plans.
2.14 FLORIDA DEPAR- OF TRANSPORTATION (FDOT)
The Drainage Section or Drainage Design Office is a subsection of the Florida Department of Transportation (FDOT) responsible for roadway drainage, stomter management, and bridge hydraulics for state-maintained roadways. The following information was obtained from the FDOT Deland off ice:
o Bridge map showing locations and identification numbers;
o General highway map showing State Highway system with identification numbers;
o Bridge construction detail plans for selected Lake County bridges; anca
o Inventory list for state road straight-line diagrams in Lake County.
In addition, the following data have been obtained from the Florida Turnpike Authority:
o Straight-line diagram showing roads and stormwater management facilities for the Florida Turnpike in Lake County.
Further coordination with the FDOT for specific facility data details will be done during future phases of the County's Stormwater Management Program. 2.15 FLORIDA DEPARTMJ3NT OF COMMUNITY AFFAIRS (DCA)
FLORIDA DEPARTMENT OF COMMUNITY AFFAIRS
The DCA is the implementation agency for State Comprehensive Plan (Chapter 187, Florida Statutes). Chapter 9J-5, FAC outlines local comprehensive plan elements which are submitted to the DCA after receiving comments from the local regional planning council (such as the East Central Florida Regional Planning Council).
The DCA has produced several documents to assist local governments in meeting the requirements of the 1985 and 1986 Growth Management legislation. By steering local planners to the key resources that will help them understand the issues confronting their communities, the documents can better prepare local officials and the public to make the kinds of critical decisions that Florida's future growth demands. The following DCA publications were obtained:
o Preparing a Comprehensive Plan, Practical Considerations in Meeting Florida's Local Planning Requirements, May 1987 - This document's intent is to enable local governments to engage in the type of planning process which meets the statersplanning requirements, and which effectively responds to the community's needs and priorities for directing future growth.
o Sanitary Sewer, Solid Waste, Drainage, Potable Water, and Natural Groundwater Aquifer Recharge Element - Model Element, May 1987 - This "model element" is one of eleven prepared by the DCA in response to Chapter 163, Florida Statutes. The purpose of this model or sample element, is to provide an example of one approach that would be found in compliance with that Chapter.
o A Guide to Local Government Comprehensive Planning Data Sources, A Directory to Assist Local Governments in Preparing Local Comprehensive Plans Pursuant to Chapter 163, F.S. and Chapter 9J-5, FAC, November 1986 - The DCA has prepared this publication to assist local governments in identifying sources of information that are considered useful for comprehensive planning purposes.
EAsT CENTRAL FLORIDA REGIONAL PLANNING COUNCIL (ECFRPC)
One of the primary activities of the ECFRPC, located in Orlando, is to review Developments of Regional Impact (DRI) and provides planning assistance to local communities. Since the ECFRPC is the lead agency in the review process for DRIs, CDM contacted this entity in order to obtain stornrwater facility information contained in all DRIs and other applicable planning data.
The following ECFRPC publications have been obtained:
o 208 Areawide Water Quality Management Plan, Orlando (FL) Metropolitan Planning Area, 1978;
o Floodplain Maps in the Lake County Conservation Element;
o Lake County Land Use Mapping Project, Comprehensive Planning Assistance Program, November, 1986 - This report summarizes and presents the land use mapping and planning assistance performed by the ECFRPC for the Lake County Board of County Commissioners. It will provide Lake County with the maps needed to fulfill the existing land use requirements of Chapter 9J-5, FAC;
o Upper Palatlakaha Basin Comprehensive Water Study, Technical Report, May 1983, East Central Florida Regional Planning Council;
o Upper Palatlakaha Comprehensive Water Study Water Quality Report, September 15, 1982, Lake County Department of Pollution Control;
o Review of Approaches and Techniques Used in the Financing of Retrofit Stornrwater Management Projects, 1985-1986 - This publication is intended to present a summary review of financial alternatives that have been used to fund the undertaking of retrofitted improvements to existing storm drain systems in urban areas and techniques which offer potential for possible use in alleviating the funding problem; and o Results and Findinas of an Urban Stormwater Runoff Retentionfletention Facility Pollutant Removal Monitoring Project, August 1983 - The objective of the project was to determine the pollutant removal efficiency of a small-sized stormwater retention/detention facility located in a built-up, developed urban area. 3.0 HYDROLOGIC/HYDRAULIC BACKGROUND
MAJOR BASINS
Lake County is approximately 1,172 square miles in size and includes a portion of the Ocala National Forest. Average rainfall is approximately 51 inches and much of the County provides recharge to the Floridan Aquifer, Florida's primary supply of potable water. The County lies on the central Florida hydrologic divide which causes discharge of surface and intercepted groundwater to both the Atlantic Ocean and the Gulf of Mexico. Elevations range from near sea level along the St. Johns River to over 300 feet at Sugar Loaf Mountain.
The County is aptly named due to the presence of more than 1,300 lakes. Most of these lakes were created by erosion of underlying carbonaceous bedrock causing a Karst topography and sinkholes connecting surface waters to the aquifers. Two stream-to-sinkhole systems have been identified: Wolf Branch sink east of Mount Dora, and the Shocklee Heights area sink in the Ocala National Forest northeast of Lake Dora. Portions of the County contain considerable physical relief (e.g., Mount Dora Area) with well drained soils while other portions are flat and comprised of extensive wetlands (e.g., Little Everglades). Surface streams and rivers, such as the Oklawaha and Withlacoochee Rivers, convey surface and groundwater discharges out of the County on their way to the Atlantic Ocean and Gulf of Mexico, respectively. The Lake County Conservation and Groundwater Recharge Elements of the Countyts Comprehensive Plan provide further details on conservation and groundwater aspects of the hydrology of Lake County.
Lake County contains five major hydrologic basins: Oklawaha River, Withlacoochee River, Wekiva River, Kissimmee River, and the St. Johns River. These major hydrologic basins are shown on Figure 3-1 and are described below. These descriptions provide basic facts about location, size, and stream systems. The identification of problem areas, data evaluations, and recommendations for each major basin are addressed in other sections within this report. 0Fz=Y-F7 m 11 es
WITHLACOOCHEE
OKLAWAHA
LEGEND - MAJOR BASIN DIVIDE
WITHLACOOCHE RIVER
MAJOR BASINS enwronmen to1 engrneers, scren tists. planners, a monogemen t consultants CDM FIGURE 3-1 3.1.1 OK- RIVER
Approximately 50 percent of the County lies within the Oklawaha River Basin which extends from Polk County to the south and Marion County to the north. The contributing area within Lake County for the Oklawaha River Basin is approximately 582 square miles and the direction of flow is generally south to north. The Oklawaha River discharges to the St. Johns River, north of Palatka. It also receives flows from portions of Orange and Lake Counties.
The upper Oklawaha River Basin, as found in Lake County, consists of the majority of major lakes, streams, and rivers in the County. The two main lake chains, the Palatlakaha Chain and the Apopka Chain are divided by the Lake Wales Ridge. A series of streams and canals connect the Palatlakaha Chain which extends from Lake Louisa in southern Lake County to Lake Harris where it connects to Lake Eustis via the Dead River. The most distant water source of the lakes in this chain is the eastern portion of Green swafig*
The second principal lake chain, the Apopka Chain, extends from Lake Apopka in Orange and Lake Counties through Lake Griffin. The major lakes of this chain are connected by canals or channelized waterways. In both lake chains, the flow is regulated by lock and dam structures. Several freshwater springs are located within the Upper Oklawaha River Basin.
RIVER
Approximately 17 percent of the County lies within the Withlacoochee River Basin which extends from the northeastern part of the County adjacent to the Town of Lady Lake to the southwestern part in the Green Swamp area, which is a large wetland area that serves as the headwaters for several river systems. The Withlacoochee River Basin area within Lake County is approximately 201 square miles and the direction of flow is generally north to south. The Withlacoochee River ultimately discharges into the Gulf of Mexico. 3.1.3 WEKIVA RIVER
Approximately 18 percent of the County lies within the Wekiva River Basin. Located in the northeastern part of the County, the basin extends from Lake Dorr southeasterly along Blackwater Creek to its confluence with the Wekiva River, near the Lake/Orange County border. At this point, the Wekiva River flows northeast outfalling into the St. Johns River which discharges into the Atlantic Ocean at Jacksonville, Florida. The Wekiva River Basin area within Lake County is approximately 205 square miles.
3.1.4 KISSIMMEE RIVER
Approximately 2 percent of the County lies within the Kissimmee River Basin. Located in the southeastern part of the County, the basin extends from Trout Lake to the LakePolk County border. The Kissimmee River Basin area within Lake County is approximately 21 square miles and generally flows north to south. The Kissimmee River flows south and ultimately discharges to Lake Okeechobee.
3.1.5 ST. JOHNS RIVER
Approximately 14 percent of the County flows directly into the St. Johns River. Located in the northeastern part of the County, the basin extends from Alexander Springs in the Ocala National Forest to the Town of Astoe: adjacent to the river. The St. Johns River Basin area within Lake County is approximately 166 square miles and generally flows south to north.
3.2 HYDROLOGIC BOUNDARIES
Hydrologic boundaries are needed to identify flow directions and schemes as well as contributing area acreages. As agreed upon with Lake County, hydrologic boundaries for major basins (e.g., Oklawaha River), sub-basins, and smaller hydrologic units were derived from SJRWMD and SWFWMD estimates coupled with the Lake County Drainage Atlas. These boundaries were digitized as AutoCAD layers at the USGS 7.5 minute quadrangle scale (1"=2000t). Appendix B contains the Hydrologic Boundary Map for Lake County and lists the five major basins with their respective hydrologic sub-basin areas. The five major basins are comprised of 18 sub-basins and 250 hydrologic units.
3.3 TOPOGRAPHY
Topographic data are needed to define hydrologic boundaries, overland flow slopes, channel slopes, and stage-area-storage relationships. Topographic data are available for the entire County from the USGS as 1:24,000 (7.5 minute series quadrangles with 5-feet contours) and 1:100,000 scale maps (5-feet contours). One-foot contour topographic-aerials (scale 1"=200t) also exist for portions of the County as available from the LCWA and SWFWMD. Figure 3-2 shows the extent of this detailed topographic coverage.
3.4 AERIAL PHOTOGRAPHY
Aerial photographs aid stormwater evaluations in land use verification, basin delineations, hydraulic facility identification, calculation of overland flow lengths, floodplain storage encroachment, and survey requests.
Aerial photographs are available from the LCWA and SWFWMD with topography for much of the County (at a scale of 1"=200t). In addition, the standard FDOT aerials are available through Lake County, and Real Estate Data Index (REDI) maps are also available at various scales.
The LCWA and SWFWMD topographic-aerials, augmented by either FDOT or REDI aerials where needed, are recommended for use in future phases of the County's Stormwater Management Program.
3.5 SOILS
Soils data are used to evaluate stormwater runoff, infiltration, and recharge potential. Specifically, infiltration rates and total soil storage (related to curve number) are used in hydrologic models. 012 4 6 8 miles
......
LEGEND AREA OF TOPOGRAPHIC- AERIAL COVERAGE BY LCWA AREA OF TOPOGRAPHIC- AERIAL COVERAGE BY SWFWMD
DETAILED TOPOGRAPHIC COVERAGE en vironmen fa1 engineers, scien fists, planners, & management consu/tants CDM FIGURE 3-2 Information on soil types and engineering characteristics can be obtained from soil survey reports produced by the Soil Conservation Service (SCS). The Lake County and Ocala National Forest Soil Surveys are in the process of revision and should be available for future stomter projects. This information may also be available in digital form through the LCWA ARC-INFO system. Site specific soils studies can also be used to augment or clarify SCS reports as they are submitted for specific developments.
The Generalized Soil Map in the Lake County Soil Survey (1975) was used to identify soil types for the eighteen sub-basins. Figure 3-3 shows this preliminary mapping of generalized soil types in Lake County, and Appendix B contains a table which lists soil types by sub-basin.
In general, hydrologic group A and B soils can be used for infiltration Best Management Practices (BMPs) as well as detention BMPs, while hydrologic group C and D soils are suitable for wet detention BMPs only, although in some cases, swales can be used in type C soil areas. Wetland creation/enhancement is best achieved in type D soils, but also in other type soils if an impermeable pond bottom material such as clay is used. Section 5.0 provides background discussion of soil types.
3.6 RAINFALL
Rainfall data are used to generate the basis for stormwater evaluations. Data are generally characterized by amount (inches), intensity (inches per hour), frequency (years), duration (hours), temporal (time) distribution, and spatial distribution. Rainfall amounts for the Lake County area are shown on Figures 3-4 through 3-8 for the 1-, lo-, 25-, and 100-year 24-hour storm events and the 25-year, 96-hour storm event.
Based upon these storm event rainfall amounts and the location of the major basins in Lake County, rainfall amounts and peak rainfall intensities were developed for the major basins, along with a recommended temporal distribution. This information is presented in Table 3-1. 0- 0- miles
HYDROLOGIC SOIL GROUP
POLK
GENERALIZED SCS SOILS environmen to/ engineers, scien fists. planners. & monogemen t consulton ts CDM* FIGURE 3-3 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT p.,+&NASSAU --4L-22
!
4.4
MEAN ANNUAL 24-HOUR MAXIMUM RAINFALL FOR NORTHEAST FLORIDA, INCHES environmen to1 engineers, scfen tists, planners, & management consultants CDM FIGURE 3-4 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
I
10-YEAR 24-HOUR MAXIMUM RAINFALL FOR NORTHEAST FLORIDA, INCHES ADAPTED FROM SJRWMD, 1988
FIGURE 3-5 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
FOR NORTHEAST FLORIDA, INCHES
FIGURE 3-6 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
N
100-YEAR 24-HOUR MAXIMUM RAINFALL FOR NORTHEAST FLORIDA, INCHES ADAPTED FROM SJRWMD, 1988
FIGURE 3- 7 ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
ADAPTED FROM SJRWMD, 1988 FIGURE 3-8 TABLE 3-1 DESIGN STORMS RECOMMENDATIONS FOR THE MAJOR BASINS
STORM STORM PEAK EVENT EVENT RAINFALL RAINFALL RAINFALL FREQUENCY DURATION AMOUNT INTENSITY MAJOR BASIN DISTRIBUTION (YR) (HR (IN) ( IN/HR) Oklawaha River SCS Type I11 1 2 4 4.2 and 2 2 4 4.8 Kissimmee River 5 2 4 5.9 10 2 4 6.7 2 5 2 4 8.5 50 24 9.8 100 24 11.5
Wekiva River SCS Type I11 1 2 4 4.3 and 2 2 4 4.9 St. Johns River 5 2 4 5.9 10 2 4 6.5 25 2 4 8.3 50 2 4 9.6 100 2 4 11.3
Withlacoochee SCS Type 111 1 2 4 4.2 River 2 2 4 4.8 5 2 4 6.0 10 2 4 6.8 2 5 2 4 8.5 50 2 4 10.0 100 24 11.8
NOTES : (1) The SCS Type I11 rainfall distribution was formerly called the SCS Type II-Modified or Florida-Interim. (2) Rainfall amounts for the 1-, lo-, 25- and 100-year, 24-hour storms are taken from SJIWMD Technical Publication 88-3 "Rainfall Analysis for Northeast Florida". Rainfall amounts for the 2-, 5-, and 50-year, 24-hour storms are derived from a least squares regression of rainfall amounts for the other storms. (3) The rainfall amount for the 25-year, 96-hour storm for landlocked areas is recommended to be 11.0 inches for all basins using an SCS Type 111 distribution. Orlando, Lake Alfred, Deland, Sanford, Isleworth, and Eustis. The active recording locations are shown in Figure 3-9. Table 3-2 presents the mean and maximum annual precipitation amounts for the recording locations. These data were used to screen for historic Levels Of Service and for potential calibration storms.
A time series evaluation was performed using the rainfall data mentioned above. Of the significant rainfall events isolated (greater than 2.0 inches), those with the least spatial variance were designated as possible calibration events. The ideal calibration storm would be relatively recent (within five to ten years) and be of a frontal nature with rainfall evenly distributed over an entire basin or the entire study area. In addition, the ideal storm should be on the order of magnitude of one of the larger storm events (e.g., lo-, 25-, and/or 100-year frequency) to help calibrate and verify design storm simulation results. Such an ideal storm was not found for this study due to the lack of significant rainfall events in recent years. However, the January 10-11, 1986 rainfall event represents a widely-distributed, significant event which produced rainfall amounts of 5.4 inches at Lisbon and 4.9 inches at Clermont. This corresponds to approximately a 2- to 3-year frequency storm and is recent enough for present hydrologic and hydraulic conditions to be applicable. Another possible calibration event is the November 23, 1988 rainfall event which was concentrated over the southern portion of the County producing 6.9 inches at Clermont and 1.9 inches at Lisbon. Table 3-3 shows the results of a historic storm analysis for Lake County.
Based upon this evaluation, it appears that adequate calibration data exist for future stormwater calibration modelling efforts.
3.7 STAGE AND DISCHARGE
An essential component of any water resources investigation is the availability of measured stages and/or discharges at selected points of interest. These are often used to establish base flows or normal conditions as well as predict extreme flood and/or drought event conditions. LEGEND
RAIN GAGE STATION - DISTRICT BOUNDARY --.- STATE BOUNDARY -.- COUNTY BOUNDARY TABLE 3-2
RAINFALL SUMMARY FOR WCE COUNTY AREA, FLORIDA
Mean Maximum Period of Record Rain Gage Annual Annual Precipitation Precipitation ( inches ) ( inches ) Bushnell 50.50 77.11 1950-1989 Clermont 51.30 68.09 1949-1989 Inverness 55.59 86.97 1950-1989 Lake Alfred 51.28 75.81 1959-1989
Ocala 53.95 74.71 1949-1989 Orlando 48.32 56.79 1975-1989 Sanford
AVERAGE TABLE 3-3 ESTIMATED WATER QUANTITY BASED ON HISTORIC STORMS
AF'PROXIMATE 3-GAGE STORM AF'PLICABLE GAGES AND AVERAGE FREQUENCY MAJOR BASIN RAINFALL AMOUNTS ( INCHES) ( IN) (YR)
LISBON CLERMONT WCE ALFRED OK- RIVER 5.4 6.9 4.8 5.7 5
WEKIVA RIVER & LISBON DELAND SANFORD ST. JOHNS RIVER 5.4 5.0 6.7 5.7 5
WITHLACOOCHEE L ISBON CLERMONT BUSHNELL RIVER 5.4 6.9 6.0 6.1 5
KISSIMMEE ISLEWORTH CLERMONT WCE ALFRED RIVER 5.0 6.9 4.8 5.6 5
NOTES : (1) All rainfall values were rounded to the nearest 0.1 inch. (2) The three most applicable gages were used to triangulate for a given basin. (3) Level of Service frequencies were estimated as the storm which most evenly matched the 2-, 5-, lo-, 25-, 50-, or 100-year events. Typically, for a stormwater master plan, stages and/or discharges are used in conjunction with known rainfall amounts/distributions and other hydrologic/hydraulic conditions to calibrate and verify models. These calibrated and verified models can then be used in evaluations of present problem area solutions or future conditions planning. It is often desirable to acquire these data in at least hourly intervals such that relatively short term, yet potentially damaging, flood peaks can be predicted and planned for.
For this study, CDM contacted various sources for such data including the following:
o The USGS for stage values at the twenty gages recording lake stages in the study area (Table 3-4 and Figure 3-10);
o The USGS for discharge values at the twenty-one gages recording stage and flow for streams in the study area a able 3-5 and Figure 3-11 ) ;
o The USGS for partial-record crest-stages and other miscellaneous sites in the study area;
o The USGS for major well data in the County (Table 3-6); and
o The SJRWMD and the LCWA for any available stage/discharge data.
In general, there appears to be adequate stage and/or discharge data for the stormwater master plan and detailed basin plan efforts, however, the necessary unit (or hourly) stage values will require a special retrieval from the USGS computer database at that time.
3.8 FLOODPLAINS AND FLOOJ3WAYS
A floodplain is basically the area inundated by a particular flood event. Floodplains are often described by their frequency of occurrence (e.g., 25-year, 100-year). TABLE 3-4 USGS LAKE GAGES IN THE STUDY AREA
PERIOD NATERBODY GAGE # OF RECORD LOCATION Lake Lowery Southeast end of Stub Canal on south side of lake Lake Nellie 1.8 mile east of SR 561 Lake Louisa North shore or lake Lake Minnehaha Southeast side of SR 561 bridge Lake Asphawa Northwest shore of south portion of lake Cherry Lake Southwest shore of lake, 21' upstream from outlet Church Lake West shore of lake, 0.8 mile south of U.S. 27 Lake Harris Northwest shore of lake Johns Lake North shore of lake, 0.4 mile south of SR 50 Lake Apopka Southeast corner of west boat basin Lake Francis North shore of lake at Errol Estates (Orange County) West Crooked lake East shore of southeast bay of lake Lake Dora West shore of lake Lake Umatilla South shore of lake Lake Eustis Northeast shore of lake Silver Lake West shore of lake TABLE 3-4 (continued) USGS LAKE GAGES IN THE STUDY AREA
PERIOD WATERBODY GAGE # OF RECORD LOCATION Lake Yale 02238200 9/59 - C East bank, southeast side of lake Lake Griffin 02238300 5/36 - C West portion of lake Lake Dorr 02235150 8/65 - C West shore of lake Lake Catherine 02312670 9/65 - C Northeast shore of lake Lake Odom 02236119 11/80-C Southwest shore of lake ,---4--1 L------_I I POLK COUNTY
USGS LAKE GAGES environmen to1 engineers, scientists, planners. & monogemen t consu/tont~ CDM FIGURE 3-10 TABLE 3-5 USGS STREAM GAGES IN THE STUDY AREA
PERIOD m-DY GAGE # OF RECORD LOCATION Tracy Canal 02235192 On left bank at downstream side of culverts on county road, 0.5 mile upstream of Lake Norris 2.1 mile downstream from Lake Tracy St. Johns River Left bank on downstream Near Deland, FL side of Francis P. Whitehair Bridge, SR 44, 142 mile upstream from mouth Blackwater Creek At bridge SR 44, 13 mile upstream from mouth Big Creek Near left bank 40 feet downstream from Log Bridge, 1 mile upstream from mouth to Lake Louisa Little Creek 0.6 mile upstream of Lake Louisa Palatlakaha River 21 feet upstream of at Cherry Lake outlet of Cherry Lake Palatlakaha River 20 feet downstream of at Cherry Lake outlet of Cherry Lake Palatlakaha River 260 feet upstream of near Mascotte, FL spillway, 0.4 mile downstream of bridge at SR 565 Palatlakaha River 250 feet downstream of near Mascotte, FL spillway, 0.4 mile downstream of bridge at SR 565 Palatlakaha River 50 feet upstream of at Structure M-6 Control Structure M-6 TABLE 3-5 (continued) USGS STREAM GAGES IN THE STUDY AREA
PERIOD GAGE # OF RECORD LOCATION Palatlakaha River 02237011 150 feet downstream of Below Structure M-6 Control Structure M-6 Palatlakaha River 50 feet upstream of at Structure M-6 Control Structure M-6 Palatlakaha River 150 feet downstream of Below Structure M-5 Control Structure M-5 Palatlakaha River 50 feet upstream from at Structure M-4 Control Structure M-4 Palatlakaha River 150 feet downstream from at Structure M-4 Control Structure M-4 Palatlakaha River 150 feet upstream from at Structure M-1 Control Structure M-1 Apopka - Beauclair 80 feet upstream from Canal lock and dam Apopka - Beauclair 300 feet upstream of Canal bridge at CR 48 Haines Creek 900 feet upstream of bridge at SR 44 Haines Creek 750 feet upstream of bridge at SR 44 Lake Nellie Outlet Private pier on southwest shore of lake. 0- 0- rn~les
LEGEND 02240000 ki STREAM GAGE AND ID NUMBER
USGS STREAM GAGES enwronmen to1 engineers, soen t~sts. planners. & monogemen t consulton ts CDM. FIGURE 3-77 TABLE 3-6 USGS WELL GAGES IN THE STUDY AREA
WELL I.D. # PERIOD OF RECORD LOCATION East side SR 33, 1,000 feet north of SR 474 East side SR 33, 1,000 feet north of SR 474 South of SR 565, 800 feet west of Seaboard Coastline Railroad Crossing East side of SR 565, 3.6 mile south of SR 50 East side of SR 565, 3.6 mile south of SR 50 Lake Avenue, 0.2 mile north of SR 50 North side of Little Lake Harris, 0.2 mile west of SR 19 On west side of College Street, near water tank, 350 feet north of Main Street North side of Herlong Park, 450 feet north of US 441 70 feet east of SR 454, 2.7 mile south of Astor Park 200 feet north of SR 40, 1 mile west of St. Johns River at Astor Park Two classifications of floodplains are typically considered in stormwater analyses: tidal and stormwater. Tidal floodplains are the result of tide and wind generated flood stages while stormwater (sometimes called fluvial) floodplains are associated with riverine flooding resulting from rainfall.
It is common practice for FEMA floodplain studies to consider tidal and stormwater flood events to be independent of one another and then superimpose the independent results upon each other to produce comprehensive tidal/stormwater floodplain maps. For Lake County, only riverine floodplains occur. Therefore, evaluations in Lake County do not need to consider tidal effects.
A floodway is often defined specifically by the FEMA standard. For example, Section 2.0(k) of the SJRWMD MSSW Applicant's Handbook states in part:
"Floodway - The permanent channel of a stream or other watercourse, plus any adjacent floodplain areas that must be kept free of any encroachment in order to discharge the 100 year flood without cumulatively increasing the water surface elevation more than a designated amount (not to exceed one foot except as otherwise established by the District or established by a Flood Insurance Rate Study conducted by the Federal mergency Management Agency (FEMA))."
Proper floodplain/floodway data are critical to guiding new development in the establishment of first-floor elevations, road crown elevations, lake control structure and tailwater elevations, allowable fill quantities/ encroachments, and facility sizing.
Floodplains and floodways have been predicted by FEMA in Flood Insurance Studies (FISrs)for the County and Incorporated Areas; however, CDM has only been able to obtain portions of these data. Therefore, these data are still being sought to prepare for master plan needs. For this M, CDM will coordinate with ongoing FEMA efforts to ensure that the planning efforts of this program will be consistent with accepted flood insurance standards and methodologies.
3.9 LAND USE AND GROWTH TRENDS
Land use data are used to estimate imperviousness, runoff, and pollutant load potential in stormwater evaluations. Relative changes in land use are also used to identify areas of high growth for the estabishment of priorities for study.
Present land use (1986), as supplied by the Lake County Planning Department, was used to estimate land use by percentages for each of the eighteen subbasins. Table 3-7 lists the ten land use groupings used by CDM to characterize areas based on similar runoff and pollutant load potential. Table 3-8 shows the correlation between the CDM categories and Lake County categories. Appendix B provides a list of land use percentages by subbasin.
The future land use element was not completed in time to be included in this study; however, relative changes in population have been assessed and were used by CDM to characterize high growth areas to help establish priorities for the Stormwater Master Plan. The following Growth Areas were defined jointly by CDM and the Lake County Planning Department in order to estimate relative changes in imperviousness:
o High Growth - greater than 67 percent population change;
o Medium Growth - between 33 and 67 percent population change; and
o Low Growth - less than 33 percent population change.
Most of the County is expected to experience medium growth while high growth areas tend to be in the Oklawaha River Basin and Lady Lake areas. Figure 3-12 shows the respective zones. TABLE 3-7 IMPERVIOUSNESS BY LAND USE CATEGORY
PERCENT LAND USE CATEGORY 1MPERVIous~ ' DCIA 2 , 1. Forest, Open, and Park 2. Agricultural and Golf Courses 3. Pasture 4. Low Density Residential 5. Medium Density Residential 6. High Density Residential 7. Light Industrial, Commercial, and Institutional 8. Heavy Industrial 9. Wetlands 10. Watercourses and Waterbodies
' ' Total Impervious Area. ( ' Directly Connected Impervious Area (DCIA). TABLE 3-8 CDM vs COUNTY LAND USE CATEGORIES
CDM ECFRPC
1. Forest, Open, & Park Recreational Vacantflndeveloped Forested Uplands Other Barren Lands Altered Lands 2. Agricultural and Golf Course Agricultural 3. Pasture Range land 4. Low Density Residential Residential (S.F. - Low Density) 5. Medium Density Residential Residential (S.F. - Medium Density) Residential (M.H. - Medium - Density ) Mixed Residential Residential Under Construction Mixed Use 6. High Density Residential Residential (S.F. - High Density) Residential (M.H. High Density ) Residential (M.F. - Low Rise) Residential (M.F. - High Rise) 7. Light Industrial, Commercial, Commercial and Services & Institutional Industrial Transportation Communication and Utilities Public/Institutional Extractive 8. Heavy Industrial Industrial 9. Wetlands Wetlands
10. Watercourses & Waterbodies Water 0- 0- miles
MARION
LEGEND 1-1 1-1 HIGH GROWTH
1-1 1-1 MEDIUM GROWTH LOW GROWTH NOTE: GROWTH DESIGNATIONS ARE AS DEFINED BY LAKE COUNTY PLANNING DEPARTMENT
HIGH GROWTH AREAS environmental engineers, scientists. planners, & manogemen t consultants CDM FIGURE 3-12 REGIONAL AQUIFER CHARACTERISTICS
The Lake County Chapter 9J-5, FAC Groundwater Recharge and Conservation Elements present various data on regional aquifer characteristics; however, it is important to correlate the following issues to surface and stormwater management :
o Lake County contains extensive recharge areas for the Floridan Aquifer (Figure 3-13). Therefore, recharge protection is essential for potable water supplies for the area (Section 3.0 provides further details on recommendations); and
o Discharges to groundwater via sinkholes in Karst areas and discharges via drain wells can adversely impact the quality along with saltwater intrusion zones of groundwater supplies. Therefore, these types of areas have been evaluated as problem areas in Section 2.0 and recommendations are contained in Section 3.0.
o Major wells and springs have also been included in Figure 1-6 as an indicator of locations for groundwater discharges and monitor locations by the USGS.
3.11 INVENTORY OF MAJOR STORMWATER CONVEW4NCE STRUCTURES
Information on hydraulic facilities can be obtained from several sources. Supporting data files to FEMA FIS reports are occasionally sources of hydraulic parameters for those structures studied by FEMA. No such data have been available to date for this study. An index for diagrams showing size and location of stormwater structures has been obtained from the Florida Department of Transportation for all state roads in Lake County. Engineering plans and as-builts (e.g., subdivision plans) submitted to Lake County are additional sources of hydraulic data that can be examined to avoid excessive field surveying requirements. om om miles
24 1 25 1 26
LEGEND Q SPRINGS AREAS OF GENERALLY
AREAS OF LOW RECHARGE AREAS OF MODERATE
7 MAJOR USGS WELLS
GROUNDWATER CHARACTERISTICS en wionmen to1 engineers, scientists, planners, & monogemen t consultants CDM FIGURE 3-73 For this phase of the County's overall Stormter Management Program, CDM and the Department of Public Maintenance Supervisors for Districts 1, 2, and 3 performed extensive field confirmation of stormwater facilities serving each major County road. These field surveys were limited to culverts with a capacity equal to, or greater than, a 36" circular pipe. Each facility was measured for diameter, height, or width and condition. Appendix B contains a table listing these facilities (Stormwater Facility Inventory). The table contains the listing of facilities by USGS quadrangle, ID code (e.g., B04005 is facility 5 in sub-basin B04), description, and maintenance entity. Field reconnaissance by CDM engineers and County staff has provided, and will continue to provide, vital information needed to analyze key hydraulic components of the primary stomter management system. 4.0 STORMWATER MANAGEPENT REGULATIONS
This Section provides a description of the regulatory and intergovernmental framework which should be considered to regulate and implement the Lake County Stormwater Management Program.
LAKE COUNTY
The existing Lake County regulations are in the process of revision. The County's drafted Stomwater Management Ordinance will provide regulatory guidelines and Design Standards for new development. The Ordinance Design Standards stress the following key features necessary for a sound stomwater management system:
o Pollutant Abatement;
o Rechargemere Possible;
o Protection From Flooding; and
o Erosion Protection.
Lake County is also seeking delegation from the SJRWMD for some of its current surface water management regulatory programs.
4.2 CITIES AND TOWNS
This section presents a comparison of existing stormwater management ordinances and design standards for the cities and towns located within Lake County with the County's proposed Stormwater Management Ordinance. Of the 14 cities and towns reviewed, none had a separate stormwater management ordinance but addressed stormwater management issues in their subdivision ordinances. The results of the comparison are summarized in Table 4-1. TABLE 4-1
COMPARISON OF EXISTING STORMUAATER MANAGEMENT ORDINANCES AND DESIGN STANDARDS
City of Town of Town of City of Lake Fruitland City of City of City of City of Town of Howey-in Lady Town of City of City of bunt City of City of ORDINANCE/DESIGN STANDARDS County Park Groveland Mascotte Minneola Umatilla Astatula the-Hills Lake bntverde Leesburg Tavares Dora Eustls Clermont ----
Stormwater Management Ordinance X ---- Subdivision Ord inance - Design Standards X X X X X X X X X X X X X X ----
General X X X X X X X X X X X X X X ------I------. - Pollution Abatement X X X X X X X ------.------I-----.------.------.------. - Recharge where Possible X X X ------I------.. - Protection from Flooding X X X X X X X X X X X X X X ------. - Erosion Control X X X X X X X ----
Disposition of Stomwater Runoff X X X X X X X X X X X X X X ----
Oevelopnent within Areas of Special flood Hazard (100-year flood) X X X X X X X X X X ----
Design Criteria X X X X X X X X X X X X X ------. - Methods of Computing Runoff Volune and Peak Rate Discharge X X ------*------. - Oesign Storm (minimum) X X X X X X X X X X ------em------...... ------1-1------.-. - Storm Distribution X -.------.------.-.------. - Detentlon/Retentlon Pond Criteria X X X X X X X ------a------.------.---*------Open Channels X X X X X X X X X X X ----I TABLE 4-1 [continued)
COMPARISON OF EXISTING STORMWAATER MANAGEMENT ORDINANCES AND DESIGN STANDARDS
City of Town of Town of City of ORDINANCEIDESIGN STANDARDS Lake Fruttland Ctty of Ctty of City of City of Town of Howey-In Lady Town of Ctty of City of Mount Ctty of City of [conttnued) County Park Groveland lhscotte Uinneola Unatllla Astatula the-Hills lake bntverde Leesburg Tavares Dora Eustis Clermont ----
Hydraul tc Destgn Crtterta X X X X X X X X X X X X X X ----*--- --**------.-*------.------*------.***--- -.-*.**--* *-*-.------*-**---.------.----*--.* --.------.------..---.-.I - Roadway (Pavement) Dratnage Design X X X X X X X X X X X X X X 0.-*------*---- .------*------.--*-.- -*----*--* ..-*------*-*--**--- O-***II...- ..-*..*-* ---...-.---.-..-*..-. ..---..--.---..--- 0- --**..------.-.-'b - Storm Sewer Destgn X X X X X X X X X X X X X ------*---- *------*--- *------* ------***- *CII*IIII* *-***------**------***------*------*-*------.-.---.-----*.-.--01* - Culvert Destgn X X X X X X X X X X X X X ----
Stormwater Management Plan Requirements X X X X X X X X X X X X X X ---.----*-*----.-*- --.*------* -----*---- .--.------*-----* ------**------*- --*---*-*-- .----.------*------*-*-- ---.------*--*--Ia. - Stormater Map X X X X X X X X X X X X X X .--..-** --*-----*** ---om-----* .----***-- I.*-*------*-- -*---*-*-* ---*------* -----*-** -*---.------*--*------*--*---- eII-I-*-- ---.**--- -.-----.-I. - Subsotl Investtgatton X X X X X ***---*- 0-.--****-* -.*----**-* -**.--*--* -*--1--.-- -*--*---t* ----*---*- -*-*----**- --**------*---- OI-I--*I------I------e*** 0-*--.--0a. - Stormwater Calculattons X X X X X X X X X X X X X X ---- Proof of Legalloperatton Entity El tgtbtltty X X X X X X X X X X *-*----* ---.--*--*- ----o*-*--- --**----.- .---I*---* --*-----*- -*---.------*----*- -*-*----* ----*---.-- -*-*------.---.---*-*-.--* C-llll-t. m1--0--01*. - Hmeowners. Property Owners. or Master Assoctatton X X
---.***- --*-*--I-** *------*--* ---*-*---- *-C--t-**O -*-*-**--I *-*---**I* -*--*..---- ..**I----- *----.*.-*- -t--w.**-- *e-*-.--. ----I.--- *O*C-*I.. -..O--*--OI. Condomtnium Association X
--**-*I- *I**-----** *------*-*I-*-**----- .*---*--I- -o*--*II-I ------*------*------.--*I *-**-*-*--I .---*--*-- --.-*-e*- ----..*-.- -*--**--- *.-.C*I--It - Assoctatton Requtrements X *--*--** *---**--*-- -**----***- --*--*-t-* *------.- ----*---*- --*-*----. --.-*-*I--*---.**.-- .**.-*,-I-* ....-*.0.0 O-I*I-*-- *-0*11**0 -*e-**-.- *-Cl-e.o.3. - Submtttal Variances X X X X X X X X X X X X X X -**-**I- --*.o***--- **-*-*****- --..-*-I-- --.---*--- *-***----* --*-**--I ---*I*------*--. O-*l---.-*- .*--**-I-- *---.*--- --Co**I.lo **-***-*. -..---.---.. Easements X X X X X X X X X X X X X X 4 ---- NOTES: (1) X - Items covered tn County. Ctty, and Town Stormwater Ordtnances or Destgn Standards.
(2) Lake County's revtew Is based on thetr draft Stormwater Ordtnance. Important notes of interest are described below:
o The majority of the ordinances, though general in nature, included a statement indicating that the improvements will be designed and installed in accordance with the criteria of the Lake County Pollution Central Department and the St. Johns River Water Management District (SJRWMD).
o Pollution abatement was not explicitly addressed in several of the ordinances.
o Groundwater recharge where possible was not explicitly adressed in the majority of the ordinances.
o ~esignmethodologies regarding computation of runoff, design storms, storm distribution, and retention/detention pond criteria were not explicitly addressed in several of the ordinances.
o Subsoil investigations were not explicitly required in several of the ordinances.
o The majority of the ordinances required proof of legal/operation entities to provide maintenance of the proposed improvements. Specifics regarding the creation of homeowners associations, etc. were not explicitly addressed.
In conclusion, the majority of the subdivision ordinances reviewed contain basic information providing a foundation for development of a stomter management ordinance. The municipalities should be encouraged to develop and adopt ordinances, paralleling the requirements of the Lake County Stomter Management Ordinance and the criteria of the St. Johns River Water Management District to properly guide future development. 4.3 FEDERAL AND STATE
UNITED STATES ENVIROIWSlT& PROTECTION AGENCY
The USEPA was mandated by Congress through Section 405 of the Water Quality ~ctof 1987 to promulgate a National Pollutant Discharge Elimination System (NPDES) permitting program for municipal stormwater discharges. Since the population of Lake County does not exceed 250,000, the County will not have to apply for a NPDES permit in the first tier of application.
UNITED STATES AFUW CORPS OF ENGINEERS
The USACOE does not regulate stormwater management, but it does regulate dredge-and-fill, as well as plan navigation and flood control projects. Many of the early flood studies in Florida were conducted by the USACOE. Close coordination with the Jacksonville District regarding dredge-and-fill will be essential to implementing regional management alternatives.
FLORIDA DEPARTMENT OF ENVIRONMENTAL REGULATION
The FDER has historically regulated dredge-and-fill and stormwater discharge quality under Chapters 17-3 (Water Quality), 17-4 (Permits), 17-12 (Dredge and Fill), 17-22 (Drinking Water), and 17-25 (Regulation of Stormwater Discharge), Florida Administrative Code (FAC). FDER recently delegated much of its stormwater discharge quality permitting and some dredge-and-fill permitting to the St. Johns River Water Management District (Sm). FDER has also been delegated as the Surface Water Improvement and Management (SWIM) administration agency (Chapter 17-43, FAC) which must oversee and approve SWIM projects as proposed and implemented by the various water management districts.
ST. JOHNS RIVER WATER MANAGEPENT DISTRICT
The SJRWMD is responsible for groundwater and storwater management under FAC Chapters 40C-2 (Consumptive Use), 40C-3 (Well Construction), 40C-4 and 40C-40 (Management and Storage of Surface Waters, MSSW), 40C-5 (Artificial Recharge), 40C-6 (Works of the District), 40C-41 (Surface Water Management Basin Criteria), 40C-42 (Regulation of Stormwater Discharge), and 40C-43 (Silviculture). In addition, its responsibilities are being expanded to regulate some dredge-and-fill permitting.
Since SJEiWMD has the most directly applicable jurisdiction, its criteria and standards will often be used as the guidelines for conceptual planning of both water quality and quantity improvements.
FLORIDA DEPARTMENT OF COMMUNITY AFFAIRS
The FDCA is the implementation agency for the State Comprehensive Plan (Chapter 187, Florida Statutes). Chapter 9J-5, FAC, outlines local comprehensive plan elements which are submitted to the FDCA after receiving comments from the local regional planning council (Northeast Florida Regional Planning Council).
The requirements of Chapter 95-5 are met or exceeded by water management district and/or county requirements. Therefore, compliance with SJRWMD and City regulations will ensure compliance with the local and state comprehensive plan requirements.
FLORIDA DEPARTMENT OF TRANSPORTATION
The FDOT has traditionally been the highway construction, operation, and maintenance agency in Florida. Recently, the FDOT has been delegated stormwater permitting authority for stormwater discharges which impact state or federal roadways.
It is often desirable to coordinate stormwater Capital Improvement Programs with FDOT projects, where possible, since major stormwater management infrastructure are often contained in FDOT projects. FLORIDA DEPAR- OF NATURAL RESOURCES
The FDNR regulates activities on state sovereign lands up to the mean high water line. This is often waterward of the SJRWMD 10-year flood elevation. The DNR does not issue permits, but rather all~ws/grants permission to trespass on public lands. The FDNR should be contacted regarding the potential placement of facilities within the sovereign waters-of-the-state if such a need arises to retrofit existing development to protect receiving waters. 5.1 GENERAL
Water quality data are needed to document adverse impacts to waterbodies/watercourses and flora/fauna. Stormwater generates non-point source pollutant loads which can degrade water quality. Traditionally, water quality data are collected in regular intervals (e.g., quarterly) to record ambient conditions in a given location.
The Lake County Department of Environmental Services Pollution Control Division maintains an extensive network of water quality monitoring stations throughout the County. Within the Oklawaha River chain, 26 lake and river stations are sampled on approximately a quarterly basis. Within the Palatlakaha River basin, 30 lake and river stations are monitored. The water quality monitoring data represents ambient conditions in a given location. The majority of the nonpoint pollution loads that are discharged into Lake County lakes are associated with stormwater runoff. Model loading projections for existing land use condition in Lake County watersheds indicate that more than 70 percent of the annual total-P and lead loads are transported by surface runoff. As urbanization increases, imperviousness within the watersheds this proportion can also be expected to increase.
Storm event sampling should be considered as part of the Lake County watershed monitoring program. Initially, only limited storm event sampling may be feasible (e.g., one or two stations); however, as Lake County staff gain experience with sampling methods and equipment the storm event sampling program can be expanded.
The occurrence of stormwater runoff in a watershed is a random process, therefore, development of reliable storm event water quality data requires a more sophisticated sampling program than ambient baseflow water quality assessments. When storm events occur, especially in Lake County watersheds with short travel times, the peak loadings of pollutants in stormwater may occur before personnel are able to arrive at a site and begin manual sampling. For this reason, it is usually desirable to use automatic flow monitoring and water quality sampling instruments. Manual sampling has the advantages of lower costs, simplicity, and more flexibility. However, these advantages are more than outweighed by the potential for failure to obtain data when storm events occur. CDMrs experience with nonpoint source monitoring has shown that a wet weather sampling program incorporating automatic monitoring equipment will have the best chance for success. As part of EPArs upcoming NPDES permitting program for stomwater discharges sampling of storm events at 5 to 10 outfalls will be required.
Storm event monitoring can be used to document the effectiveness of a stormwater management plan in improving water quality. The primary purpose of a stormwater monitoring program is to provide baseline data and to evaluate future water quality trends (e.g., improving versus deteriorating conditions).
5.2 BEST MANAG- PRACTICES (BMPs)
Best Management Practices (BMPs) are techniques, approaches, or designs which promote sound use and protection of natural resources. Various types of BMPs are discussed extensively in Chapter 6 of the FDER Land Development Manual, 1989. The following BMPs are being applied in Lake County:
NON-STRUCTURAL SOURCE CONTROLS
Fertilizer Application Control Pesticide Use Control Solid Waste Collection and Disposal Source Control on Construction Sites Stormwater Management Ordinance Requirements STRUCTURAL STORMWATER CONTROLS
Concrete Grid and Modular Pavement Detention Basins (Wet and Dry) Exfiltration Trenches Grassed Waterways and Swales Parking Lot Storage Porous Asphalt Pavement Retention Basins Rooftop Runoff Disposal Storageflreatment Facilities (e.g., oil and grease skimmers) Underdrains and Stormwater Filter Systems
EROSION AND SEDIMENT CONTROL PRACTICES
Erosion and sediment control practices are addressed in the Draft Lake- County Stormwater Management Ordinance by CDM.
All of these practices are important in the sound management of water resources in the County. For stormwater quality enhancement applications, the following sections discuss the relative merits of structural BMPs.
5.2.1 STRUCTURAL BMP ALTERNATIVES
The structural BMPs screened for applications in Lake County were:
Infiltration Controls: These BMPs are also referred to as "stormwater retention" controls. They divert stormwater runoff into the soil profile where pollutant removal can occur as a result of natural "treatment" processes such as filtration, adsorption, and oxidation by soil microorganisms. Examples include: infiltration/retention basins and trenches, swales, exfiltration systems, underdrains, dry wells, and porous and modular pavement. 2. Detention Controls: These BMPs achieve removal of suspended pollutants through sedimentation processes and, in the case of wet detention basins, the removal of dissolved pollutants through physical, chemical, and biological processes within the basin's permanent pool. Examples of these are dry and wet detention ponds.
5.2.2 COMPARISON OF STRUCTURAL BMPs
Except for swales, infiltration BMPs require much more frequent maintenance and major cleanouts than detention basin BMPs (CDM, 1985). Infiltration BMPs tend to require major cleanouts nearly every year or so to eliminate clogging conditions. In the absence of an intensive, continuing maintenance program, these BMPs will tend to fail within a few years after start-up. In addition, because infiltration BMPs require highly permeable soils which are not restricted by a high water table, these devices will be limited to those sections of the study area based on case-by-case applications (e.g., with Class A soils and a low water table). However, retention controls can be very effective where such suitable conditions exist, and these are recommended for new recharge requirements on hydrologic group A soils that the County is considering in their draft Stormwater Management Ordinance. In addition, retention BMPs provide high levels of pollutant removal from surface waater discharges, although soluble pollutants are ultimately discharged to the groundwater. Where infiltration BMPs are used for surface water quality protection, a storage volume requirement of 0.5 inch of runoff per impervious acre is the most appropriate design standard (CDM, 1985).
Two different detention basin BMPs are currently used for runoff pollution control: wet detention and extended dry detention. In wet detention basins, pollutant removal occurs primarily within a permanent pool during the period of time between storm events. The "extended dry" method provides increased detention times for captured first-flush runoff in order to enhance solids settling and the removal of suspended pollutants. In comparison with extended dry detention basins, wet detention basin BMPs offer the advantage of pollution removal mechanisms for dissolved phosphorus and dissolved nitrogen. Whereas dry detention systems can only rely upon solids settling processes for phosphorus and nitrogen removal, wet detention can achieve removal of dissolved nutrients through other physical/chemical and biological processes in the permanent pool (e.g., uptake of nutrients by free-floating algae and wetland vegetation around the edge of the pool). ~s a result, monitored average pollutant removal efficiencies (USEPA, 1983; NVPDC, 1983) for wet detention basin BMPs are on the order of 2 to 3 times greater than extended dry detention BMPs in the case of total-P (50-60 percent vs. 20-30 percent) and 1.3 to 2 times greater in the case of total-N (30-40 percent vs. 20-30 percent). The increased removal rates for total-P and total-N in wet detention basins can be attributed in large part to average removal rates on the order of 50-70 percent for dissolved nutrients, the nutrient fraction that is most readily available for biological activity and of greatest interest from a water quality management standpoint. Urban non-point pollution monitoring studies in northern Virginia found that dissolved nutrient fractions represented up to 60 percent or more of total-P and up to 80 percent or more of total-N (NVPDC, 1983).
For other pollutants, the average removal rates for wet detention basins and extended dry detention basins are very similar (USEPA, 1983; NVPDC, 1983): 80-90 percent for total suspended solids; 70-80 percent for lead; 40-50 percent for zinc; and 20-40 percent for BOD or COD. The efficiencies for extended dry detention basins are based on an average hydraulic residence time of 2 weeks or greater for permanent pool of wet detention basin, and 12-24 hr detention time for extended dry detention basin with a storage capacity of 1.0 inches of runoff per impervious acre. The major difference between the performance of wet and dry detention basins is the greater removal of nutrients in the former, therefore wet detention basins are more appropriate than extended dry detention basins for areas where the receiving water quality problems are caused by nutrient loadings.
A schematic diagram of a wet detention basin is shown in Figure 5-1. As may be seen, the facility consists of a permanent storage pool (i.e., section of the pond which holds water at all times) and an overlying zone of temporary storage to accommodate increases in the depth of water resulting from runoff. As shown in Figure 5-1, pollutant removal within the wet detention basin can be attributed to the following important pollutant removal processes which occur within the permanent pool: uptake of nutrients by algae and rooted aquatic plants; adsorption of nutrients and heavy metals onto bottom sediments; biological oxidation of organic materials; and sedimentation of suspended solids and attached pollutants.
Uptake by algae and rooted aquatic plants is probably the most important process for the removal of nutrients. Sedimentation and adsorption onto bottom sediments is probably the most important removal mechanism for heavy metals. Aerobic conditions at the bottom of the permanent pool will maximize the uptake of phosphorus and heavy metals by bottom sediments and minimize pollutant releases from the sediments into the &ter column. Since ponds that exhibit thermal stratification (i.e., separation of the permanent pool into an upper layer of high temperature and a lower layer of low temperature) are likely to exhibit anaerobic bottom waters during the summer months, relatively shallow permanent pools that maximize vertical mixing are preferable to relatively deep basins.
Wet detention basin BMPs do offer some other advantages which should be considered in BMP selection. Wet detention basins are usually more attractive looking than dry basins, particularly if there is extensive wetland vegetation around the perimeter of the permanent pool. When properly designed and constructed, wet detention basins are actually considered as property value amenities in many areas. Also, wet detention basins offer the advantage that sediment and debris accumulate within the permanent pool. Since these accumulations are out-of-sight and well below the basin outlet, wet detention basins tend to require less frequent cleanouts to maintain an attractive appearance and prevent clogging.
If the contributing area is too small, storm runoff and dry weather inflows into the wet detention basin may be too small to maintain a permanent pool during "dry" seasons. While excessive drawdown of the permanent pool does not pose a non-point pollution control problem, it will cause aesthetic problems. Suggested guidelines for minimum contributing areas of wet detention basins are presented later in this section.
The potential impacts of stormwater management structures on wetlands are addressed and monitored by the FDER. While it can be argued that wet detention basins can be designed to produce new wetland systems and that the additional water quality protection justifies potential wetlands impacts, extreme care and precautions must be exercised where stormwater treatment is provided through the use of existing wetlands.
5.2.3 DESIGN CRITERIA FOR PREFERRED STRUCTURAL BMPs
The most important feature of a wet detention basin is the permanent pool. Urban runoff detained in the permanent pool following a storm event is subjected to physical/chemical and biological processes which achieve removal of selected pollutants. During the next storm event, urban runoff inflows displace "treated" waters in the permanent pool followed by treatment after the storm ends. This means that the size and shape of the permanent pool is an important design criterion. For example, the larger the permanent pool storage volume in comparison with design runoff conditions (e.g., first 1.0 inch of runoff), the lower the outflow of urban runoff inflows and the higher the retention and treatment between rainstorms. Two different methods are available for design of wet detention basins: (1) solids settling design method; and (2) lake eutrophication model design method.
Solids Settling Design Method
The solids settling design method (Driscoll, 1983) relies upon rainfall/runoff statistics, settling velocities for assumed particle size distributions, and the assumed percentage of pollutant mass attached to sediment (particulate fraction) in order to calculate suspended pollutant removal for specified overflow rates. Separate efficiency calculations for dynamic conditions during storm events and for quiescent conditions following storm events are weighted by the duration of each condition to determine a long-term average pollutant removal rate. The method assumes an approximate plug flow system in the detention basin, with all pollutant removal resulting from Type I sedimentation. While this assumption may be reasonable for dynamic conditions during storm events, completely mixed conditions which account for longitudinal dispersion may be more likely under quiescent conditions. Pollutant removal under quiescent conditions is based upon a capture/pumpout model originally developed for evaluations of combined sewer overflow (CSO) interceptors. For permanent pool storage volumes typically considered for wet detention basins, the solids settling method usually assigns more than 90 percent of the total pollutant removal to quiescent conditions and less than 10 percent to the dynamic conditions which are probably best represented by the plug flow assumptions of the design model.
Design curves for the solids settling method for wet detention basin design are shown in Figure 5-2. As may be seen, these curves relate average TSS removal to the size of the permanent pool. For these particular design curves, the permanent pool size is expressed in terms of the ratio of its surface area to the BMP contributing area. Since these curves are based upon a mean depth of 3.5 ft for the permanent pool, the x-axis can easily be converted to a permanent pool storage volume (i.e., product of surface area and mean depth).
This design method is most appropriate for handling suspended solids and constituents such as heavy metals (e.g., lead) which tend to appear primarily in suspended form, since sedimentation should be the dominant pollutant removal process. However, it is less appropriate for the evaluation of nutrient removal efficiencies since monitoring data at several NURP wet detention basin sites indicate that the majority of total-P and/or total-N mass removal was in the form of dissolved P and dissolved N. This is illustrated in Table 5-1 which summarizes average removal of total-P and dissolved P monitored at the NURP wet detention basin sites and other testing sites. As may be seen, dissolved P removal represents a major component of total-P removal at seven of the ten sites which reported dissolved P removal rates. For example, the portion of the total-P efficiency attributable to dissolved P removal ranged from 62 percent to 8 percent for four of the NURP sites. This suggests that solids
TABLE 5-1 MONITORED WET DETENTION BASIN EFFICIENCIES TOTAL-P AND DISSOLVED P SUMMARY
Aver age Dissolved P Hydraulic Average Average Fraction of Residence Total-P Dissolved P Total-P Time Removal Removal Removal Location Site (weeks) (%I (%I (%I
A. NURP Ladsing, MI Grace N. Lansing, MI Grace S. Ann Arbor, MI Pitt Ann Arbor, MI Swift Run Ann Arbor, MI Traver Long Island, NY Ungua Washington, DC Burke Washington, DC Westleigh Glen Ellyn, IL Lake Ellyn Lansing, MI Waverly Hills B. USGS (1986) Orlando FL Highway Pond 1-2 29% 54% 63% C. Minnesota TwinCities,MN Fish 5 44% 32% 47% Roseville, MN Josephine 6 62% 69% 75%
SOURCE: Walker, 1987 settling theory alone does not account for the most important nutrient removal mechanisms in wet detention basin BMPs.
Lake Eutrophication Model Design Method
This approach assumes that a wet detention basin BMP is a small eutrophic lake which can be represented by empirical models used to evaluate lake eutrophication impacts (Walker, 1987; Hartigan, 1988). The intent of this approach is to use lake eutrophication models to account for the significant removal of dissolved nutrients observed in the field and attributable to biological processes such as uptake by algae and rooted aquatic vegetation. Using this design method, a wet detention basin can be sized to achieve a controlled rate of eutrophication and an associated removal rate for nutrients.
The design method is restricted to nutrients. However, since wet detention basin BMPs that achieve significant nutrient removal also achieve removal rates for other pollutants that are similar to other BMPs, it is probably not necessary for the design method to address other constituents besides nutrients. Likewise, wet detention basin BMPs may not be cost-effective unless nutrient control is the principal water quality management objective.
The recommended lake eutrophication design model is the phosphorus retention coefficient model developed by Walker (1987). Like most input/output lake eutrophication models, this model is an empirical ' approach which treats the permanent pool as a completely mixed system and assumes that it is not necessary to consider the temporal variability associated with individual storm events. Unlike the solids settling model which accounts for temporal variability of individual storms, the Walker model is based upon annual flows and loadings. Because it does not consider storm to storm variability, this model is much simpler to apply than the solids settling model.
To test how well the model represents wet detention basin B~s,Walker (1987) applied it to 10 NURP sites and 14 other wet detention systems and small lakes. The goodness-of-fit assessments yielded an R~ of about 0.8, indicating that the model does a good job of replicating monitored average total-P removal from detention basin design characteristics.
5.2.4 POLLUTANT REMOVAL EFFICIENCIES
Based upon NURP monitoring studies of BMPs, the following average pollutant removal efficiencies are often used in evaluating wet detention basin BMPS:
o Total P: 50 percent
o Total N: 30 percent
o Lead: 80 percent
o Zinc: 70 percent
These average annual efficiencies are consistent with design criteria for wet detention basins.
5.3 REGIONAL VS. ONSITE DEPLOYMENT OF STRUCTURAL BMPs
ADVANTAGES OF REGIONAL APPROACH
Figure 5-3 illustrates the two different approaches that can be taken for deployment of structural BMPs for watershed protection:
Onsite Approach: In the case of future urban development, this option involves the delegation of responsibilities for BMP deployment to local land developers. Each developer is responsible for constructing a structural BMP(s) at his develop ment site to control non-point pollution loadings from the site. Detention basin BMPs provided onsite typically have drainage areas of 20-50 acres. The local government is responsible for reviewing each structural BMP design to ensure conformance with specified design criteria, for inspecting the constructed facility to ensure 0 Z -V) m--I < In ONSITE REGIONAL 2J (Each developer provides BMP on development sile) m (Strategically located by local government) !2 0 >Z I- CD I 73
I
I i i b, 9. a 2 3 $ !+; 2"3 - 8$3 9 2? 8, 2 2 sg , 3 % 2 .: ALTERNATIVES FOR BMP DEPLOYMENT I I -- - conformance with the design, and for ensuring that a maintenance plan is implemented for the facility.
2. Regional Approach: This option involves strategically siting regional structural BMPs to control non-point pollution loadings from multiple development projects. The front-end costs for constructing the structural BMP are assumed by the local government which administers the regional BMP plan. BMP capital costs are then recovered from upstream developers on a "pro-ratall basis as development occurs. Individual regional BMPs are phased in as development occurs rather than constructing all regional facilities at one time. Maintenance responsibility for regional structural BMPs is generally assumed by the local government.
In developing stomter and watershed management programs during the 1970fs,local governments often elected to use the piecemeal approach because it required no advanced planning and, therefore, it appeared relatively easy to administer. While the lack of planning requirements does give this approach an advantage in comparison with the comprehensive approach, the disadvantages far outweigh this benefit.
A regional BMP system offers benefits which are equal to or greater than onsite BMP benefits at a lower cost. Most of the advantages of the regional approach over the onsite.approachcan be attributed to the need for fewer structural facilities which are strategically located within the watershed. The specific advantages of the regional approach are summarized below:
o Reduction in capital costs for structural BMPs: The use of a single stormwater detention facility to control runoff from 5 to 15 development sites within a 500-1,000 acre subwatershed permits the local government to take advantage of economies-of-scale in designing and constructing the regional facility. In other words, the total capital cost (e.g., construction, land acquisition, engineering design) of several small onsite detention BMPs is greater than the cost of a single regional detention basin BMP which provides the same total storage volume. o Reduction in maintenance costs: Since there are fewer stomwater detention facilities to maintain, the annual cost of maintenance programs are significantly lower. Moreover, since the regional detention facility recommended in the master plan can be designed to facilitate maintenance activities, annual maintenance costs are further reduced in comparison with onsite facilities. Examples of design features that are typically only feasible at regional BMP facilities to reduce maintenance costs include: access roads that facilitate the movement of equipment and work crews onto the site (by comparison, detention facilities implemented under the onsite approach are often located in residential backyards); additional sediment storage capacity (e.g., sediment forebay) to permit an increase in the time interval between facility clean-out operations; and onsite disposal areas for sediment and debris removed during clean-out. o Greater reliability: The bottom line is that a regional BMP system will be more reliable than an onsite BMP system because it will be more likely to be maintained. With fewer facilities to maintain and design features which reduce maintenance costs, the regional BMP approach is much more likely to result in an effective long-term maintenance program. Due to the greater number of facilities, the onsite BMP approach tends to result in a large number of facilities which do not get adequately maintained and therefore soon cease to function as designed. Most cities and counties who start off with the onsite approach eventually switch to the regional approach to address the lack of maintenance of the onsite systems and to increase the overall effectiveness of the stomter management program. Good examples are Fairfax County, Virginia, and Montgomery County, Maryland, where problems with the effectiveness of an onsite stormwater control approach eventually led to the implementation of a regional approach. o Opportunities to manage existing non-point pollution loadings: b on-point pollution loadings from existing developed areas can be affordably controlled at the same regional facilities which are sited to control future urban development. This is because the provision of additional storage capacity to control runoff from existing development in the facility's drainage area should be relatively inexpensive due to economies-of-scale. BY comparison, the costs of retrofitting existing development sites with onsite detention BMPs to control existing non-point pollution loadings would probably be prohibitively expensive. o Fair to land developers: Land developers recognize that economies-of-scale available at a single regional BMP facility should produce lower capital costs in comparison with several onsite detention facilities. They also tend to prefer the regional BMP approach because it eliminates the need to set aside acreage for an onsite facility, and therefore could permit an increase in the number of dwelling units within the development site. o Multi-purpose uses: Regional facilities can often be landscaped to offer recreational and aesthetic benefits. Jogging and walking trails, picnic areas, ballfields, and canoeing or boating are some of the typical uses. For example, portions of the facility used for flood control can be kept dry, except during floods, and can be used for soccer or football fields. Wildlife benefits can also be enhanced in the form of islands or preservation zones which allow a view of nature within the park schemes. Figure 5-4 shows a profile view of a typical multi-purpose facility. Gradual swales can also be worked into the park concept to provide pre-treatment around paved areas, such as parking lots. Figure 5-5 shows a typical swale detail.
--I 4 -73 0 > r cn >s r m
GROUNDWATER TABLE -:--^------7----,------...... --3-,------A*------...... B ...... 7...'.....',.,., ...... "" ...... : ) :.. :...... :.: .:.. :',:, .:.:,.:.:..:.:. .:.:.:'.:..: ...... :.: ...... 2 3 ...... , . , . , . , . , . , ...... :..... s:.:. *. .::, .:::.:. .:.:. .:.;..:.:::.:. .:.:. ~;.~~::.;:::. .. q 5...... :;,:.;:.:...:...... :. ....:...... '" 9 ...... :. P; 3, 2% 2 2 4 '2. 4 a NOTES: - 7 0 -'" 2 8 I. SLOPES SHALL BE NO STEEPER THAN 4H: IV AND 2 2 2 2 6H: I V IS PREFERRED. 2 2 G; S 2. SWALE INVERT SHALL BE AT LEAST 1-2 FEET ABOVE THE SEASONAL HIGH WATER TABLE.
3. SWALES SHALL BE GRASSED AND CHECK DAMS PLACED AS NEEDED TO CONTROL OVERFLOWS AND VELOCITIES. ' 5.4 WATER OUALITY EVALUATIONS
This section presents an evaluation of water quality within selected lakes and rivers within Lake County. The evaluation is based upon available historical monitoring data compiled by the Lake County Department of Environmental Services, Pollution Control Division during the period 1985 through the first quarter of 1990.
5.4.1 MISTING LAKE COUNTY MONITORING
Lake County has been monitoring ambient conditions within lakes and streams for more than five years. Samples have been collected approximately on a quarterly basis and analyses are performed for the following parameters:
PARAMETER ABBREVIATION UNITS Secchi Depth (field) SECCHI meters Temperature (field) TEMP deg. C Dissolved Oxygen (field) D.O. mgfi pH (field PH Stan. Units Specific Conductance (field) COND uhmos/cm Phenol Alkalinity P-ALK mgfi Methyl Alkalini ty M-ALK mgfi Chlorides CG mgfi Ammonia-N NH4-N mgfi Organi c-N ORGN mgfi Nitrate+Nitrite-N NOX-N mgfi Total Phosphorus Total-P mgfi Orthophosphate Or tho-P mgfi Biochemical Oxygen Demand BOD-5 mgfi Turbidity TURB. NTU Total Suspended Solids TSS mgfi Chlorophyll-a CHLOR-a ugfi ~otall analyses are performed on every sample. Some parameters have been intermittently dropped or performed on irregular intervals. The water quality monitoring data are entered into a spreadsheet database which is kept up to date. The database also includes the time and date of sample collection and the water column depth that the sample was collected from. In general, field parameters are recorded at the surface or at 0.3 meters. Laboratory analyses are performed on samples collected at one half of the total depth at the sampling station. Chlorophyll-a samples are collected from one half the secchi depth or 0.3 meters whichever is greater.
CDM obtained copies of the available water quality monitoring data for the period 1985 to present from the Lake County Department of Environmental Services. Water quality monitoring data are available for eleven of the twelve lakes selected for stomwater pollutant loading evaluations. The eleven lakes include; Lake Beauclair, Lake Dora, Lake Harris, Little Lake Harris, Lake Louisa, Lake Mimehaha, Lake Mimeola, and Lake Yale. Lake Carlton is the only lake included in the stomwater pollutant loading analyses for which no water quality monitoring data were obtained.
Summary statistics for each of the study area lakes is presented in Table 5-2. Mean, maxim, and minim values as well as the number of samples (N) are summarized for selected pollutant parameters. These mean concentrations are shown graphically in Figures 5-6 through 5-9 for total-P, total-N, secchi depth, and chlorophyll-a. Within Lake Beauclair, average concentrations of total-P are in excess of 0.20 mgfi Average total-N concentrations in Lake Beauclair are almost 4.0 mgfi. High average total-P concentrations are reported for Lake Dora and Lake Griffin. Average total-N concentrations in Lake Dora and Lake Griffin are greater than 3.0 mgfi
Chlorophyll-a, a pigment that is present in all types of algae, is a common indicator of nutrient enrichment and eutrophication in a lake. Analysis of chlorophyll-a is often used to assess the biomass present in a lake. Chlorophyll-a concentrations greater than 20 ugfi are generally considered indicative of eutrophic conditions within a lake. Average chlorophyll-a concentrations reported within Lake Beauclair is more than six times this threshold at 120 ugfi. Average chlorophyll-a concentrations reported within Lake Dora is about 110 ugh. Chlorophyll-a concentrations ranging from about 35 ugfi to 70 ugfi which are also indicative of eutrophic conditions, are observed in lake Eustis, Lake Griffin, Lake Harris, and Little Lake Harris. TABLE 5-2
SUMMARY OF LAKE WATER QUALITY MONITORING DATA SOURCE: Lake County Dept. of Environmental Services
LAKE BEAUCLAIR SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a ImlOW lSUl~~m(ma/LIIma/LImmmm UlU Mean 0.32 23.4 9.6 8.9 369 114 40.8 0.14 3.72 0.04 0.21 7.6 12.3 121.2 N 15 15 15 15 15 16 16 13 15 10 15 13 13 13 Max 0.50 31 .O 14.2 9.4 424 132 45.5 0.36 5.02 0.27 0.33 13.4 22.5 214.5 Min 0.2 15.0 5 8.3 310 80 36.5 0.02 1.94 0.01 0.08 0 6 22 LAKE CHERRY SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a ImlLdeaC)w lSUllumtmmmWmm mmm lualU Mean 2.00 25.2 7.3 6.5 96 5 21.2 0.08 0.53 0.01 0.012 1.9 1.2 3.84 N 24 25 25 25 25 25 25 17 24 1 18 6 25 19 Max 3.00 33.0 9.5 7.5 118 11 40.5 0.20 0.70 0.01 0.03 4.2 2.3 12.0 Min 1.25 16.7 4.9 5.5 75 3 16.5 0.02 0.34 0.01 0.01 1.2 0.8 0.8 LAKE DORA SECCHl TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a m(deaCI0 woImaR)lmaRlwIma/L)m Iman)(maR)INTU) lua/U Mean 0.31 23.6 9.5 8.6 372 119 39.8 0.18 3.56 0.02 0.14 7.5 11.1 106.7 N 28 28 28 28 27 30 30 30 30 15 28 28 28 29 Max 0.60 30.0 14.8 9.5 438 138 45.5 0.58 4.38 0.03 0.38 12.5 26.0 188.4 Min 0.25 16.0 5.6 7.8 190 92 22.0 0.02 2.06 0.01 0.05 4.3 6.2 11.4 LAKE EUSTIS SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a mf!&mm womtmaR)(maRIIma/L)Ima/L) lmaRloINTU) (urJ/U Mean 0.56 23.5 8.9 8.3 314 104 30.8 0.19 2.14 0.02 0.05 3.6 7.5 45.0 N 30 30 30 30 30 30 30 30 30 11 30 30 28 29 Max 1.10 30.7 12.2 9.3 363 120 38.0 0.88 3.08 0.08 0.08 6.0 16.0 120.3 Min 0.3 16.0 4.6 7.4 230 88 25.0 0.02 1.20 0.01 0.03 1.6 3.5 10 TABLE 5-2 (Cont.)
SUMMARY OF LAKE WATER QUALITY MONITORING DATA SOURCE: Lake County Dept. of Environmental Services.
LAKE GRIFFIN SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOX-N TOTAL-P BOD5 TURB. CHLOR-a ltnl(deslCItmaRl Wfm!m(maR)mmmw lmaRl~(NTU) (ua/LI Mean 0.46 23.1 8.5 8.3 325 106 31.1 0.23 2.92 0.02 0.08 6.5 12.4 69.5 N 58 58 -58 58 57 57 57 53 56 26 58 58 52 56 Max 1.7 30.1 12.1 9 .O 400 129 39.5 1.08 6.16 0.10 0.32 78.3 24.0 196.0 Min 0.25 15.0 5.1 7.1 250 0 0.0 0.01 1.30 0.01 0.02 0.0 2.8 4.0 LAKE HARRIS SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a m(deaCIImalLI Wlumhosl~~~~ImaR)wmm Lua/U Mean 0.65 23.8 8.9 8.3 246 91 22.2 0.13 1.59 0.04 0.04 3.07 5.89 39.8 N 43 43 43 43 43 42 42 36 41 15 41 43 39 41 Max 1.O 32.0 10.8 9.1 288 102 38.0 0.38 2.40 0.12 0.08 5.6 9.5 118.0 Min 0.3 16.0 4.8 7.6 180 77 19.0 0.02 0.50 0.01 0.01 1.3 4.2 6.0 LITTLE LAKE HARRIS SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a ma!aatmaRl Wfm!mImaR)m(ma/L1ImaRlImaR) ImaRIOW lua/LI Mean 0.70 23.9 9.0 8.2 240 89 21.1 0.17 1.50 0.05 0.04 3.1 5.7 34.3 N 28 28 28 28 28 28 28 28 27 12 28 28 26 28 Max 1.20 31.2 10.6 8.9 275 96 25.0 0.74 2.32 0.16 0.1 1 5.8 8.5 123.0 Min 0.4 15.0 6.4 6.7 180 79 15.5 0.00 0.08 0.01 0.01 0 3 4 LAKE LOUISA SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a m(deaCIImaR) Wlumhos)ImaR)lmanlImall)ImaR)ImalLI ImaR)wm LualL) Mean 0.90 24.7 7.8 5.8 83 5 18.0 0.12 0.70 0.14 0.03 1.2 1.7 6.9 N 28 28 28 28 28 28 28 27 28 20 28 8 28 23 Max 1.75 32.0 10.2 6.7 113 15 20.0 0.50 0.90 0.70 0.15 1.6 3.6 18.5 Min 0.5 16.4 6.1 4.7 60 1 14.5 0.02 0.07 0.01 0.01 1 1.1 1.5 TABLE 5-2 (Cont. )
SUMMARY OF LAKE WATER QUALITY MONITORING DATA SOURCE: Lake County Dept. of Environmental Services
LAKE MINNEHAHA SECCHl TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a Iml~(maR1wLumhosltma/L)ImalLIIma/L1(maRIImaRl mom w Mean 1.64 24.7 7.6 6.3 87 5 18.9 0.07 0.54 0.11 0.02 1.2 1.7 3.7 N 28 28 28 28 28 28 28 22 28 6 21 6 28 2 1 Max 3.25 31.1 10.6 7.5 116 14 22.5 0.30 0.80 0.13 0.02 1.4 2.6 8.0 Min 1 16.4 5.5 5.2 70 3 16.0 0.02 0.14 0.09 0.01 1 1 1 LAKE MINNEOLA SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a Iml(deaCIma4 LSUllumhoslmwmmImaR) 0wINTU) lualU Mean 2.22 24.8 7.5 6.5 93 5 19.9 0.13 0.48 0.02 0.04 1.43 1.55 4.8 N 40 40 40 40 40 39 39 34 40 5 33 10 40 25 Max 5.3 33.0 9.7 8.3 122 12 22.5 0.74 1.10 0.06 0.72 2.7 2.4 20.0 Min 0.75 16.4 4.7 5.2 70 2 17.0 0.00 0.06 0.01 0.01 1 0.74 0.8 LAKE YALE SECCHI TEMP D.O. pH COND M-ALK CL- NH4-N ORG-N NOx-N TOTAL-P BOD5 TURB. CHLOR-a mh!a-QImah) w-wmmm(maRI ~~m IudLl Mean 1.8 23.6 8.6 8.1 298 107 31.8 0.14 0.83 0.03 0.02 2.1 2.6 12.4 N 28 28 28 28 27 28 27 22 30 2 27 21 30 21 Max 3.5 29.7 10.6 8.8 338 120 35.0 0.74 1.22 0.03 0.03 8.5 13.0 28.1 Min 1.0 16.0 6.5 7 240 93 28.0 0.02 0.50 0.02 0.01 1 0 1 MEAN CONCENTRATION 1985-1990: TOTAL-P LAKE COUNTY MONITORING DATA
LAKE MEAN CONCENTRATION 1985-1990: TOTAL-N LAKE COUNTY MONITORING DATA
LAKE MEAN CONCENTRATION 1985-1990: SECCHI LAKE COUNTY MONITORING DATA
I BEAUCLAIR CHERRY HARRIS LOUISA CARLTON DORA L. HARRIS MlNNEHAHA YALE LAKE MEAN CONCENTRATION 1985-1990: CHL-A LAKE COUNTY MONITORING DATA Secchi depth is a measure of the transparency of waters in a lake. The measured Secchi depth tends to decrease as water quality deteriorates. Secchi depths less than 1.0 meter have been correlated to eutrophic conditions in a lake. As shown in Figure 5-9, seven of the study area lakes exhibit average secchi disks depths less than 1.0 meter.
5.4.2 TROPHIC STATE INDEX
A preliminary Trophic State Index (TSI) was applied to the eleven study area lakes for which water quality monitoring data was available. The TSI procedure provides an effective method of classifying lakes based on the lakesf chlorophyll-a, Secchi depth, nitrogen and phosphorus concentrations. The Florida Trophic State Index was developed in 1982 in response to the EPA Clean Lakes Program. The index is based on a trophic state classifica- tion developed in 1977 by R. E. Carlson. Criteria were developed for Florida lakes from a regression analysis of data on 213 Florida lakes. The desirable upper limit for the index is set at 20 ugfi chlorophyll-a which corresponds to an index of 60. Doubling the chlorophyll concentration to 40 ugfi results in an index increase to 70 which is the cutoff for undesirable (or poor) lake quality.
A nutrient index is calculated based upon phosphorus and nitrogen concentration and the limiting nutrient concept. The limiting nutrient concept identifies a lake as phosphorus limited if the nitrogen to phosphorus concentration ratio is greater than 30, as nitrogen limited if the ratio is less than 10 and balanced (depending on both nitrogen and phosphorus) if the ratio is between 10 and 30. The nutrient TSI is based solely on phosphorus if the ratio is greater than 30, solely on nitrogen it the ratio is less than 10 and an average of the nitrogen and phosphorus TSI if the ratio is between 10 and 30.
An overall TSI is calculated based on the average of the chlorophyll-a TSI, the Secchi TSI, and the nutrient TSI. The criteria which have been established for the Florida TSI are: Water Quality TSI Indicator Good Fair Poor For each of the study area lakes, a TSI was calculated from the statistical summaries of the available Lake County water quality monitoring data. The TSI results are presented in Table 5-3. TSI values are presented for average Secchi depth, nutrient, and chlorophyll-a. In addition, ratios of average nitrogen to phosphorus concentrations are presented. Eight of the selected study area lakes appear to be phosphorus limited (TN:TP>30) while three lakes are balanced (10 5.4.3 STOFtMWATER POLLUTANT LOADINGS A preliminary evaluation of non-point pollution loadings was performed in order to assess general areawide trends and to provide a framework for more detailed analyses to be performed under the Lake County Stormwater Master Plan. The non-point pollution loading analyses provides estimates of the mass loadings (i.e., pounds per year) of pollutants from sub-basins discharging to the following lakes: Lake Beauclair, Lake Carlton, Lake Cherry, Lake Dora, Lake Eustis, Lake Harris, Little Lake Harris, Lake Griffin, Lake Minneola, Lake Minnehaha, Lake Louisa, and Lake Yale. pollutant load projections for total nitrogen, total phosphorus, lead and zinc were estimated for average annual conditions. A database of the land features within each sub-basin was required to evaluate runoff flows and associated non-point pollution loadings. Existing land use patterns in each sub-basin were derived from the 1986 Lake County Land Use Mapping Project (East Central Florida Regional TABLE 5-3 SUMMARY OF LAKE COUNTY TROPHIC STATE INDEX ANALYSES SECCHI MEAN CONCENTRATION DEPTH TOTAL-P TOTAL-N CHLOR-a TNKP TROPHlC STATE INDEX TSI JAKE Mlmanllmanl lualL)RATlOCHL-ASECCHlTOTAL-PTOTAL-NAVGTSiRANKlNG BEAUClAlR 0.32 0.21 3.9 121.2 18.2 85.9 94.6 81.4 82.9 87.6 POOR CHERRY 2.00 0.012 0.6 3.84 50.3 36.2 39.3 28.2 46.4 34.5 GOOD DORA 0.31 0.14 3.8 106.7 27.6 84.0 95.2 73.0 82.2 85.6 POOR EUSTIS 0.56 0.05 2.4 45.0 43.9 71.6 77.6 55.7 73.0 68.3 FAIR GRIFFIN 0.46 0.08 3.2 69.5 37.3 77.9 83.4 64.2 78.8 75.2 POOR HARRIS 0.65 0.04 1.8 39.8 48.8 69.8 73.0 48.4 67.3 63.7 FAIR L. HARRIS 0.70 0.04 1.7 34.3 45.4 67.7 70.7 49.1 66.6 62.5 FAIR LOUISA 0.90 0.03 1.O 6.9 33.5 44.5 63.2 44.0 55.2 50.5 GOOD MINNEHAHA 1.64 0.02 0.7 3.7 40.9 35.5 45.2 35.0 49.5 38.5 GOOD MlNNEOlA 2.22 0.04 0.6 4.8 16.3 39.5 36.1 49.9 47.1 41.4 GOOD YALE 1.8 0.02 1.O 12.4 59.9 53.1 41.6 33.9 56.0 42.9 GOOD Planning Council). Based on similarity of runoff characteristics, the land use categories for each sub-basin were identified in Table 3-7. Present land use for each of the selected lakes within Lake County is presented in Table 5-4. The total percentage of each sub-basin in urban land uses (e.g., residential+comrnercial+industrial) and agricultural land uses (e.g., pasture+cropland) is also presented in Table 5-4. Urban non-point pollution loadings tend to be governed by the amount of imperviousness associated with each land use category. The amount of imperviousness typically associated by specific urban land use categories tends to be similar throughout a particular region. The impervious cover percentage for each land use category was estimated from literature factors and other recent CDM studies in the region. WNFALL/RUNOFF RELATIONSHIPS Non-point pollution loading factors (lbs/acre/year) for different land use categories are based upon annual runoff volumes and event mean concentra- tions (EMCs) for different pollutants. The EMC is defined as the average of individual measurements of storm loading divided by the storm runoff volume. One of the keys to effective transfer of literature values for non-point pollution loading factors to a particular study area is to make adjustments for actual runoff volumes in the watershed under study. In order to calculate annual runoff volumes for each basin, the pervious and impervious fraction of each land use category was used as the basis for determining rainfall/runoff relationships. For rural-agricultural (non- urban) land uses, the pervious fraction represents the major source of runoff or streamflow, while impervious areas are the predominant contributor for most urban land uses. Annual runoff volumes for the pervious/impervious areas in each land use category were calculated by multiplying the average annual rainfall volume by a runoff coefficient. The average annual rainfall for the eight recording locations is approximately 51.1 inches (see Table 3-2). A runoff coefficient of 0.95 was used for impervious areas (i.e., 95 percent of TABLE 5-4 SUMMARY OF LAKE COUNTY LAND USE AND HYDROLOGIC SOILS GROUP LAKE laflsuk BUWCLAlBCARLTONCHERBY PQBB EUSTlS QRlRlN HARRlS LOUlSA L.HARRISMlNNEHAHAMlNNEOU YBLE Forestlopen 5.7% 7.8% 7.7% 6.7% 9.3% 12.0% 7.2% 4.6% 7.6% 7.7% 7.3% 15.1% Pasture 6.3% 5.8% 7.8% 6.0% 5.2% 6.1% 5.7% 7.4% 5.4% 8.4% 8.4% 3.1% Agricultural 16.5% 25.9% 31.3% 20.9% 22.7% 28.7% 33.2% 48.1% 45.6% 37.0% 37.0% 35.7% Low Density Resid. 3.7% 3.4"/0 2.3% 3.6% 4.2% 4.3% 2.6% 0.9% 2.0% 2.4% 2.3% 4.8% Med. Density Resid. 12.9% 9.5% 2.9% 11.3% 8.8% 5.4% 4.6% 0.5% 2.7% 2.8% 2.6% 3.1% High Den Resid. 0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% 0.1% 0.0% 0.1% 0.0% 0.0% CommJLiiht lndust 5.8% 4.4% 2.8% 5.1% 4.0% 2.9% 2.7% 1.1% 1.5% 3.2% 3.0% 1.6% Heavy Industrial 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Wetlands 6.5% 7.6% 22.5% 7.0% 9.5% 14.5% 20.3% 25.2% 16.6% 18.6% 20.3% 13.0% 42.6%35.5%22.7%39.3%36.3%26.1%23.7%12.1%18.6%19.7%19.0%23.6% Total 100% 100% 100% 1OOOh 100% 100% 10O0/~ 100% 100% 100% 100% 100°/~ Drainage Area (acres) 2,159 1,376 3,361 19,861 34,304 44,504 77,317 46,488 39,364 5,410 17,159 22,797 Hydrologic Soils Group A 52.3% 77.5% 57.2% 53.9% 49.9% 37.2% 49.6% 53.2% 79.6% 56.0% 57.0% 42.5% B 0.09'0 0.0% 0.0% 4.5% 0.4% 0.0% 0.3% 0.0% 0.4% 0.0% 0.0% 0.0% C 0.0% 0.0% 0.0% 0.0% 4.0% 8.7% 11.5% 12.6% 2.0% 0.0% 18.6% 7.6% Q47.7%22.5%42.8%41.6%45.7%54.1%38.7%34.2%18.0%44.0%24.4%49.9% Total 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% % Agriculture 22.7% 31.8% 39.1% 27.0% 27.9% 34.8% 38.9% 55.5% 51.0% 45.4% 45.4% 38.8% % Urban 22.4% 17.3% 8.0% 20.0% 17.0% 12.6% 9.9% 2.6% 6.2% 8.6% 8.0% 9.5% % Watermetlands 49.1% 43.2% 45.2% 46.3% 45.8% 40.6% 44.0% 37.3% 35.2% 38.3% 39.3% 36.6% the rainfall is converted to runoff from the impervious fraction of each land use). Therefore, the average annual runoff from impervious areas is about 48.5 inches/year. A pervious area runoff coefficient of 0.10 was used. The total average annual surface runoff is calculated by weighting the impervious and pervious area runoff factors for each land use category. Water surfaces were assumed to be 100 percent impervious. Evaporation losses were subtracted from precipitation falling directly on water surfaces. An annual evaporation rate of 50.4 in/yr was used. Average annual baseflow (i.e., dry weather flow) for rural-agricultural areas and pervious areas in urban land uses was calculated by subtracting average annual surface runoff from average annual streamflow measured at the Little Creek USGS gage (02236700) which is located in Lake County. For existing conditions, the average annual surface runoff volume from both pervious and impervious surfaces is about 4 to 6 inches/year (based upon the runoff factors presented above). Based upon the difference between total average annual flow and the average surface runoff, average annual baseflow volume under existing land use conditions is approximately 8 to 9 inches/year. This method of obtaining base flow is sufficient for a preliminary loading analysis. However, for the more detailed Master plan investigations, base flow values will be more completely identified. In other words, baseflow accounts for the majority of the average annual total flow volume. Surface runoff or stormwater flows, which occur for relatively short periods at random intervals, account for less than half of the total flow volume but the majority of the annual non-point pollution loadings. ANNUAL NON-POINT POLLUTION LOADING FACTORS Non-point pollution monitoring studies throughout the U.S. over the past 10 years have shown that annual "per acre" discharges of urban stormwater pollution (e.g., nutrients, metals, BOD, fecal coliforms) are positively related to the amount of imperviousness in the land use (i.e., the more imperviousness the greater the non-point pollution load). Since stomter management recommendations are needed as soon as practicable, it was not feasible to undertake a stormwater non-point pollution monitoring study for use in the Lake County needs assessment. In place of an expensive local stormwater monitoring program, available literature values for non-point pollution loading factors were used for the preliminary non-point pollution loading evaluation. This approach has worked quite well in some previous stomter management studies where mixed land use monitoring data was available for comparison. For example, Table 5-5 compares urban non-point pollution loading factors for total phosphorus which were derived from local monitoring studies (total monitoring costs in excess of $1.5 million) in the Occoquan Reservoir watershed of northern Virginia with loading factors based upon the median event mean concentrations (EMC) from the pooled national database for the U.S. EPA Nationwide Urban Runoff Program. As may be seen, the loading factors based upon the national database are in relatively good agreement with the local loading factors. More important, water quality management decisions based upon the loading factors would not be significantly different from those based upon the "local" loading factors. Preliminary pollutant loading analyses are limited to the constituents for which considerable loading data are reported in the literature. The non-point pollution loading evaluation was limited to the following four pollutants: total Phosphorus (total-P), total Nitrogen (total-N), lead, and zinc. Total-P and total-N are required in order to perform evaluations of eutrophication impacts. Lead and zinc are heavy metals which typically exhibit higher non-point pollutant loadings than other metals found in urban runoff. These heavy metals may be viewed as surrogates for a wide range of toxicants that have been identified in previous field monitoring studies of urban runoff pollution (USEPA, 1983). For this preliminary evaluation, loading factors applied to the Lake County study area for this evaluation are presented in Table 5-6. Preliminary non-point pollution loading factors are presented for SCS hydrologic soils group A, B, C, and D. These factors will be adapted to the specific soils in the study area. The development of these loading factors is described below. TABLE 5-5 COMPARISON OF AVERAGE ANNUAL TOTAL-P LOADING FACTORS FOR URBAN LAND USES: OCCOQUAN WATERSHED MONITORING STUDY VS. NURP NATIONAL STATISTICS Annual Annual Total-P Loadina Runoff (lbs/acre/yr) a Land Use (inches/yr) Occoquan MJRP Residential 14.4 1.1 1.2 Mixed 22.9 1.3 (50% residential and 50% commercial) Commercial 31.4 1.5 1.4 Notes : 1. Annual runoff is based upon average annual rainfall of 40.6 inches. 2. "Occoquan" loading factors are based upon northern Virginia monitoring studies of single land use watersheds (Hartigan et al., 1983; NVPDC, 1979) , 3. "NURP" loading factors are based on the following median event mean concentrations (EMCrs)for pooled nationwide NURP database: 0.383 mg/L for residential; 0.2 mg/L for commercial; and 0.263 mg/L for mixed (USEPA, 1983b). A number of studies are available which discuss non-point pollution loading factors. The Orlando Metro Areawide Water Quality Master Plan (ECFRPC, 1978) listed a series of values which are shown in Table 5-7. Based on the Tampa National Urban Runoff Program (NURP) results, two reports prepared by CDM define EMC values: Tributary Streamflows and Pollutant Loadings Delivered to Tampa Bay (for FDER, 1984) and Southeast Area Stormwater Management Study: Final Report (for Manatee County, 1985). Tables 5-8 and 5-9 present the EMC values from these two documents. Since the 1978 Orlando 208 study, sampling methods and analysis techniques have been refined by NURP approaches and data. Therefore, the Tampa NURP EMCs were used for this study because they represent the most up-to-date local data for actual storm-related pollutant loads. Also shown in Tables 5-8 and 5-9 are the assigned impervious percentages for each of the land uses. The percentages represent the percent of a particular land use area which is impervious. It should be noted that the values do not necessarily represent directly connected impervious area (KIA). Using a single family residence as an example, rain falls on rooftops, sidewalks, and driveways. The sum of these areas may represent 30 percent of the total lot. However, much of the rain that falls on the roof drains to the grass and does not directly run to the street, some infiltrates to the ground, and some runs off the property. Thus, not all of the 30 percent impervious area actually contributes as impervious area and the DCIA percentage is less than the total impervious percentage. Experience shows that the DCIA percentage is on the order of 50 to 90 percent of total impervious percentage. Another primary source of loading factor data is the "Guidebook for Screening Urban Non-Point Pollution Management Practicest'developed for northern Virginia (NVPDC, 1979). To derive these loading factors, non-point pollution loading parameters were calibrated to single land use monitoring data using the EPA NPS model, a continuous simulation non-point pollution loading model (Hartigan, et al., 1978, 1983). The EPA NPS model was then applied with an hourly precipitation record for a year of average rainfall to generate annual loading projections for individual land uses, TABLE 5-6 SUMMARY OF NONPOINT POLLUTION LOADING FACTORS BY HYDROLOGIC SOILS GROUP Typical Lot Land Use Size % Imperv Forest 0.5% Pasture 0.5% Cropland 0.5% Low Den Resid 1.0-ac 15.0% MDSF Resid .25-ac 35.0% High Den. Resid 80.0% Co-ight Indust 90.0% 0.2 Heavy Indust 90.0% Wetlands 100.0% Water 100.0% Typical Lot Lead (rngh) Zinc (mgh) Land Use Size % Imperv A B C ---B C D Forest 0.5% Pasture 0.5% Cropland 0.5% Low Den Resid 1.0-ac 15.0% MDSF Resid .25-ac 35.0% High Den.Resid 80.0% Cormn/Ligh Indust 90.0% Heavy Indust 90.0% Wetlands 100.0% Water 100.0% TABLE 5-7 EVENT MEAN CONCENTRATIONS FOR THE ORLANDo METRO AREAWIDE WATER QUALITY STUDY (ECFRPC, 1978) Land Use Single Family Residential Commercial Improved Pasture Well-drained Flatwoods Rangeland Lake TABLE 5-8 EVENT MEAN CONCENTRATIONS AND IMPERVIOUS PERCENTAGES FOR THE TAMPA BAY STUDY (CDM, 1984) Impervious Land Use TN (mg/l) TP (mg/l) Percent Single Family Residential 1.87 0.39 30% Multi-Family Residential 1.65 0.33 50% Commercial 1.18 0.15 90% ~ndustrial 1.18 0.15 70% Institutional 1.77 0.20 5% Recreation and Open 1.21 0.21 5% Undeveloped 1.15 0.15 1 % Rainfall 0.91 0.17 N/A Agricultural with BMPs 1.03 0.21 1 % TABLE 5-9 EVENT MEAN CONCENTRATIONS AND IMPERVIOUS PERCENTAGES FOR THE MANATEE COUNTY SOUTHEAST AREA STUDY (CDM, 1985) Impervious Land Use TN (mg/l) (mg/l) Percent Forest 1.02 0.16 1% Golf Course 1.21 0.21 1% Cropland 3.74 1.13 1 % Wetland 1.02 0.16 1 % Orchard 0.92 0.41 1 % Low-Densi ty Single Family 1.87 0.39 20% Residential Medium-Density Single Family 1.87 0.39 30% Residential Townhouse/Garden Apartment 1.65 0.33 50% Residential Off ice 1.18 0.15 90% Commercial 1.18 0.15 90% Extractive 1.18 0.15 45% Industrial 1.18 0.15 70% Highway 1.18 0.15 90% Waterbody 0.79 0.17 100% which were further refined to include loading factors for different ranges of imperviousness and soil textures. With the exception of the 5-acre lot single family residential category, the NPS model projections for residential land uses assumed that all pervious area was covered with fertilized lawn surfaces. For the 5-acre lot category, it was assumed that about 2 acres was covered with fertilized lawns and about 3 acres was maintained with tree cover. To account for differences in soils characteristics, loading factors were varied by hydrologic soil group. The "Guidebook" loading factors rely on soils texture classifications. For this study, hydrologic soil groups were assigned the following soil texture classifications: SCS Hydrologic Soil Soil Texture Group Classification Fine Sand, Sandy Loam Find Sand Loam Find Sand, Silt Loam Find Sand, Clay Loam In order to effectively transfer literature values for loading factors to the Lake County study area, adjustments for actual hydrologic conditions in the watersheds under study had to be made. This was done by converting literature values to event mean concentrations (EMC) and multiplying by the surface runoff volumes for each land use category as described previously. BASEFLOW LQADING FACMRS Baseflow from all land use categories was assumed to exhibit the same concentrations of nutrients and heavy metals. Based upon a review of monitoring statistics for of the following Lake County Environmental Services monitoring stations in the study area: River Station Numbers Palatlakaha River 324, 330, 331, 44 Big Creek 323 Little Creek 322 the following mean concentrations were assumed for baseflow: o Lead: 0.0 mg/L o Zinc: 0.0 mg/L These concentrations are assumed to be representative of baseflow water quality which is not impacted by point source discharges. Water quality data from the Haines Creek Muck Farm study areas reviewed however and total-P concentrations are a factor of ten higher and near total-N concentration area a factor of 2-3 higher. For each subbasin and land use scenario, total annual baseflow volume was multiplied by these loading factors to derive annual baseflow loadings discharged into the selected lakes. 5.4.4 FAILING SEPTIC TANK IMPACTS About 60 percent of the population within Lake County rely on household septic tanks and soil absorption fields for wastewater treatment and disposal. In June 1979, the Septic Tank Nonpoint Source Element of the State Water Quality Management Plan identified Lake County as one of the ten highest-ranking counties in the non-designated area of Florida for potential septic tank failure (based on soil absorption system density and soil limitations). The non-point pollution loading factors for low density residential areas, which are typically served by septic tank systems are based on test watershed conditions where the septic systems were in good working order and the septic tanks systems made no significant contribution to the monitored non-point pollution loads. In fact, septic tank systems typically have a limited useful life expectancy and failures are known to occur which cause localized water quality impacts. This section presents estimates of average annual septic tank failure rates based on a literature review, and the methodology used to calculate additional non-point pollution loadings discharged to the lakes from failing septic systems. To estimate an average annual failure rate, the time series approach proposed by the 1986 EPA report Forecasting Onsite Soil Adsorption System Failure Rates was used. This approach considers an annual failure rate (percent per year of operation), future population growth estimates, and system replacement rate to forecast future overall failure rates. AII annual septic tank failure rate of between 2 and 3 percent per year was assumed for Lake County. This is somewhat conservative as literature values reported for areas across the U.S. range from about 1 to 2 percent. For average annual conditions, it was assumed that septic tank systems failures would be unnoticed or ignored for five years before repair or replacement occurred. Therefore, during an average year, 10 to 15 percent of the septic tanks systems in the watershed were assumed to be failing. pollutant loading rates for failing septic systems were developed from a review of septic tank leachate monitoring studies. The mean concentrations of total-P and total-N assumed based upon literature values are as follows: Low 1.0 mg/L Medium 2.0 mg/L High 4.0 mg/L Annual "per acre" loading rates for septic tank failures from low density residential land uses were then estimated assuming 50 gpcd wastewater flows. The loading rates were applied to the percentage of all non-sewered residential land uses with failing septic tanks. The septic tank loading factors were added to the runoff pollution loading factors. The percent increase in annual per acre loadings attributed to failing septic tanks is: Total-P Total-N LOW 130%-180% 120%-150% Medium 160%-250% 140%-200% High 220%-400% 180%-310% Despite the large increase in annual loading rates, septic tank failures have only a limited impact on overall non-point pollution discharges. This is because the increased annual loading rates were applied only to the fraction of non-sewered residential development that are predicted to have a failing septic tank system during an average year. It should be noted that this analysis is preliminary in nature. Detailed analysis of septic tanks and their effects on water quality, similar to the July 1982 Septic Tank Water Quality Impact Study, would better guide Lake County in the efficient use of septic tanks and their effects on water quality in Lake County. 5.4.5 AVERAGE ANNUAL NON-POINT POLLUTION LOADS Average annual non-point pollution loadings discharged into the each of the study area lakes were calculated using the loading factors described earlier. Bar charts of the projected average annual non-point pollution loadings in pounds per year of total-P, total-N, lead, and zinc are presented in Figures 5-10 through 5-13. Each individual bar represents the estimated total loadings to each of the study area lakes. Since non-point pollution loading factors for nutrients (total-P and total-N) and metals (lead and zinc) are related to specific land uses and imperviousness, the comparison of projected non-point pollution loadings across the study area lakes follow similar patterns for the nutrients and metals. Ranking the study area lakes by nutrient loading tends to follow the relative size of the total area draining to each lake. The lakes with the AVERAGE ANNUAL LOAD: TOTAL-P CARLTON DORA GRIFFIN LOUISA MINNEHAHA YALE LAKE AVERAGE ANNUAL LOAD: TOTAL-N 250,000 ' CHERRY ' EUSllS HARRIS 'MINNK)~ CARLTON DORA GRIFFIN LOUISA MINNEHAHA YALE LAKE AVERAGE ANNUAL LOAD: LEAD AVERAGE ANNUAL LOAD: ZINC BEAUCIAlR CHERRY HARRIS ' .L HARRIS' 'MINNEO~ CARLTON DORA GRIFFIN LOUISA MlNNEHAHA YALE LAKE largest drainage areas (e.g., Lake Harris, Lake Louisa, Little Lake Harris, and Lake Griffin) are projected to receive the highest annual loadings of nutrients. BY comparison, ranking the lakes by projected annual loading of metals follows a different pattern which appears to be related to the amount of existing urban development within the drainage area. "Per Acre" Loads Bar charts summarizing the "per acre" loads to each of the study area lakes are presented in Figures 5-14 to 5-17. The mass loadings presented above provide an estimate on the total load discharged to the major reach segments. By normalizing the loads on a "per acre" basis, subbasins with land uses that generate disproportionately high loading rates can be identified. Figures 5-14 and 5-15 indicate that although the total mass loads of total-P and total-N discharged to the study area lakes varies significantly, the projected "per acre" contribution of nutrients is relatively fairly constant and does not appear to be a good indicator potential water quality problems. For total-P, the loading rate is about 0.6 to 0.8 lbs/ac/yr. Similarly, the upstream "per acre" contribution of total-N is about 2.5 to 3.0 lbs/ac/yr. For heavy metals, the relative differences between "per acre" contributions are more pronounced. Figure 5-16 and Figure 5-17 suggest that "per acre" heavy metals loadings from Lake Beauclair, Lake Dora, Lake Carlton and Lake Eustis are relatively higher that the remaining lakes. "Per acre" loading of lead are projected to be greater than 0.10 lbs/ac/yr, while the remaining lakes are projected to have lead loadings well below 0.08 lbs/ac/yr. This likely to be a result of the relatively larger areas of urban land uses draining to these lakes. These results are consistent with monitoring data collected during 1985 to 1990 by the Lake County Environmental Services Department. Structural Best Manasement Practices Non-point pollution loadings were calculated only for existing land use conditions. For the Stomater Master Plan, the non-point pollution AVG. ANNUAL "PER ACRE" LOAD: TOTAL-P ' BEAUCUIR ' CHERRY I EUSTIS I I HARRIS ' L HARRIS' 'MINNE~ CARLTON DORA GRIFFIN LOUISA MINNEHAHA YALE LAKE AVG. ANNUAL "PER ACRE" LOAD: TOTAL-N I BEAUCLAIA ' CHERRY I HARRIS I L HARRIS' MINNEOLA' CARLTON DORA GRIFFIN LOUISA MINNEHAHA YALE LAKE AVG. ANNUAL "PER ACRE" LOAD: LEAD AVG. ANNUAL "PER ACRE" LOAD: ZINC ------me---- CARLTON DORA GRIFFIN LOUISA MINNEHAHA YALE LAKE loading model can be used to provide a preliminary indication of the potential benefits that could be achieved by a structural best management program. An example of this analysis, might be to calculate non-point loads assuming that 100% of future urban development would be served by BMPrs with pollutant removal efficiencies equivalent to wet detention basins. Areas of existing urban development already served by structural BMP'S could also be included in this analysis. Non-Point Pollution Loadinu Taruets Future non-point pollution loadings targets may be tied to water quality goals in the Stomter Master Plan. Potential water quality goals might include: improvement, non-degradation or minimal degradation of water quality under future conditions. While mass loads of pollutants alone cannot answer whether water quality goals will be met, comparison of projected loads under existing and future conditions provides some indication as to whether future trends will be toward improving versus deteriorating conditions. An example of using the non-point pollution loading model to evaluate a water quality goal would involve calculating the ratio of future to existing loads for the of the study area lakes. A ratio of future to existing loads of 1.0 would indicate that future loads are projected to be equivalent to existing loads. A ratio of less than 1.0 would indicate declining loads in the future and greater than 1.0 increasing loads. A non-degradation water.quality goal might correspond to ratio of future to existing loads of 1.0 which might be a reasonable loading target for those lakes exhibiting good water quality under existing conditions. For those lakes exhibiting poor water quality, a ratio of less than 1.0 might be the water quality goal. Implementation of BMPts could have a profound impact in reducing future loads to the lakes. 5.5 SUMMARY This preliminary loading analysis only provides a portion of the information required to analyze water quality problems on Lake County. Based upon this analysis and ambient water quality data, it appears that several major lakes in the County are experiencing declines in water quality (e.g., ~akeBeauclair, Lake Dora, and Lake Griffin). In addition, a separate SWIM plan for Lake Apopka is in the process of implementation to correct the long-term water quality decline in that lake. In order to properly evaluate future nonpoint source pollutant load impacts on major lakes in the County, a lake receiving water quality model is needed to predict the location and magnitude of water quality impacts resulting from pollutant loadings to each of the lakes. This water quality model should be included in future phases of the County's Stormwater Management Program. 6.0 PROBLEM AREAS 6.1 GENERAL An essential task in stormwater management planning is the identification of problem areas in order to establish priorities for need in the Capital Improvements Program (CIP). As part of this, the definitions presented below were used to categorize Lake County problem areas. 6.1.1 WATER QUANTITY (FLOODING) Serious Problem Area: o An imminent threat to public safety and/or property including loss of human life, blockage of evacuation and/or emergency vehicle routes, and/or flooding of homes/buildings. This will be evaluated by the following criteria: - hzacuation/emergency roads being overtopped by flood stages from storm events equal-to or more frequent-than the 100-year, 24-hour event. - Velocities for these events greater than five feet per second for structures and three feet per second for earthen channels. - Greater-than one foot of head loss across a structure for these events. This can be an indication of potentially erosive velocities. Nuisance Problem Area: o Minor street flooding which causes inconvenience, traffic delays, and possibly the temporary blockage of secondary roads non-essential for evacuation and/or emergency vehicle use. Serious Problem Areas: o Violation of Chapter 17-3, FAC criteria unless a naturally-occurring condition of non-compliance can be documented. o Impairment of a unique environmental use: e.g., fishing, swimming, springs, threatened and/or endangered species habitat, other. o The presence of toxic, hazardous, and/or man-made inorganic/ organic substances in sediments. Nuisance Problem Areas: o Some minor changes in color, turbidity, and/or odor that may be naturally occurring or just within limits of Chapter 17-3, FAC criteria. o Qualitative assessment of water quality. It should be noted that prior to the late 1970s (i.e., the date when the State enacted most stonwater regulations) stonwater management systems were constructed to convey stomater runoff from one area to another without providing for the treatment of stormwater runoff. Thus, many stormwater systems installed prior to 1978 would need to be retrofitted should the County desire to provide the same level of service as required by current standards for the treatment of stormwater. A discussion of this retrofit problem is presented in the next section. 6.2 PROBLEM AREA IDENTIFICATION AND EVALUATIONS For this report's level of detail, facilities with capacity deficiencies, or problem areas, were identified by interviews with Lake County personnel, and personnel for cities and towns in the County, adjacent counties, and state and federal agencies. The following list of interviews was performed to identify problem areas. Problem areas for other cities, adjacent counties, and agencies were identified by letters and telephone conversations. INTERVIEW LIST Lake County Don Findell, Director of Environmental Services Jim Stivender, Director of Public Works Don Griffey, Engineering Director Larry Kirch, Chief Planner Sam Sebaali Lake County Water Authority Will Davis City of Fruitland Park Bob Allen, Public Works Superintendent City of Groveland Rodney Schultz, Director of Public Works City of Mascotte Henry Sharpe, Director of Public Works City of Minneola Gary Thornson, Director of Public Works Citv of Umatilla David Hanna, Director of Public Works Town of Astatula Olive Ingram, Town Clerk Town of Howey-in-the-Hills Gay Brumley, Town Clerk Town of Ladv Lake Chip Ross, Public Works Director Ted Wicks, Town Engineer Town of Montverde Helen Pearce, Town Clerk Based upon the interviews and review of the available data presented in Section 2.0, the problem areas presented below were identified. Field visits were conducted to assess the reported problem areas and photographs were taken for reference. In some cases, reported problem areas had already been addressed. Preliminary improvement recommendations for the unsolved problem areas were then made and conceptual probable cost estimates were determined. It should be noted that prior to implementing the suggested improvements presented below, a detailed stormwater design analysis should be performed to verify the assumptions used in this conceptual planning study. Table 6-1 presents the location of the problem areas with their respective basins and subbasins. Figure 6-1 shows the approximate location of the water quantity problem areas. Lake County LC1 - Astor Area Problem Summary Located in the northeastern portion of the County, the Astor problem area experienced flooding problems in the early eighties. This area falls entirely within the St. Johns River Basin and for the most part lies within flood prone areas as identified in Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps. Lying immediately adjacent to the River, the occurrence of a major storm event (i.e., 25-year, 24-hour) would result in widespread flooding directly LC1.7-1 TABLE 6-1 220-GG-LAKE 05/01/91 WATER QUANTITY PROBLEM AREAS BY SUB-BASIN BASIN SUB-BASIN ID # DESCRIPTION Okl awaha River Lake Weir ------ Lake Yale LC2 Lake Yale Dike Lake Griffin ------ Lake Eustis UM1 Seminole Street UM2 Lakeside Avenue Golden Triangl e LC3 Wolf Branch Road Lake Apopka ------ Lake Harris ------ Pal at1akaha MI 1 Chester Street M I2 Washington Street Wekiva River Blackwater Creek ------ Wekiva River ------ St. Johns River Alexander Springs LC1 Astor Area With1 acoochee Lady Lake LL1 Oak Grove Subdivision River Loggy Pond Swamp ------ SE Fruitland Park ------ Grovel and-Mascotte GR1 Groveland High School GR2 Gadson Avenue GR3 Baldwin Avenue GR4 Sampey Road GR5 Mount Pl easant Road G R6 Park Street GR7 Mascotte Park MA 1 Laurel Street MA2 Oaks Street Lake Okahumpka ------ Reed Hammock Pond ------ Kissimmee River Trout Lake ------0- 0- miles L LEGEND PROBLEM AREA (e.g., LC2) OR PROBLEM AREA CLUSTER (e.g., GR1-7) NOTE: FOR A LIST OF THE PROBLEM AREAS, REFER TO THE WATER QUANTITY PROBLEM AREA SECTION. WATER QUANTITY PROBLEM AREAS en wronmen to1 eng~neers,sclen tists. planners. & monogemen t consultan ts CDM FIGURE 6-1 affected by the flood stages of the river itself. Protection from flooding may be possible by building a dike around the flood prone area, and provide pumps to convey stonwater runoff from the diked area to the river. In order to have such a system permitted the following items need to be sufficiently addressed for regulatory agency approval: (1) treatment of the stormwater for the diked system; (2) no adverse flood plain or floodway conveyance impacts; and (3) providing for compensating storage. In reviewing the flood prone area, approximately two square miles would need to be diked, and the length of diked area would be east to west which would be perpendicular to the flow (south to the north) of the St. Johns River. Due to the large compensating storage volume and the apparent constriction of the St. Johns River floodway, it appears that a diked system for this area would be difficult to receive permit approval. Therefore, structural improvements may be difficult to implement in this area. Even if these improvements are permittable, non-structural controls such as floodplain development restrictions would need to be enforced. To determine whether the diked system is feasible, a future basin study of sufficient detail to address the regulatory requirements is recommended to be performed. Recommended Capital Improvements. Conduct a detailed stornrwater study for this area. Conceptual Probable Cost Estimate. Project costs for the stormwater study are estimated to be approximately $200,000. LC2 - Lake Yale Dike Problem Summary Recently a dike failed in a canal connecting Lake Yale to Lake Griffin. The dike consisted of a clay road with a 24" diameter corrugated metal pipe (CMP). Following the "wash-out", the clay road was reconstructed and a 36"'diameter CMP was installed. Riprap consisting of broken concrete blocks was placed at the entrance and exit of the culvert. Located approximately 50' east of a 10 feet wide by 12 feet high box culvert passing under County Road 452, the capacity of the CMP relative to the box culvert is small. The CMP is a constriction to the canal which when subjected to peak flows produced by major storm events results in overtopping of the dike/road. Further wash-outs could occur, although public safety does not appear in jeopardy since County Road 452 (downstream) appears to be a solid structure. Recommended Capital Improvements. Improve erosion control to protect the existing structure and allow this non-essential road to be safely overtopped for large storms. Conceptual Probable Cost Estimate. Project costs are estimated to be $16,000. LC3 - Wolf Branch Road Problem Summary In the past, major storm events have produced flooding which resulted in the overtopping of Wolf Branch Road. Two 8Ix8' CBCs were installed to pass peak flood flows under the road. A 4-1/2' high sharp crested weir with two manually controlled slide gates was installed at the culverts entrance to maintain the water surface elevation of an existing small pond immediately upstream. This was done to accommodate the request of an adjacent land owner. The presence of the weir effectively reduces the capacity of the culverts even with the slide gates fully opened. This creates the potential for overtopping of the road which would block a potential evacuation route by high flood stages or structural damage to the road itself. Higher flood stages are also predicted upstream. Recommended Capital Improvements. Widen the existing weir length to 30 feet while maintaining the desired elevation of 4-1/2' above the invert of the CBC entrance. This longer weir will increase weir capacity and mitigate some of the interactions between the culvert and weir. Erosion protection should be provided upstream and downstream of the road in the form of armorform lining or equivalent to protect the road from failure. Conceptual Probable Cost Estimate. Capital costs are estimated to be $31,000. Citv of Fruitland Park No problem areas requiring capital improvements have been identified at this time. Citv of Groveland The City of Groveland reported the most problem areas of all cities and towns located in Lake County. There are seven problem areas located in the City of Groveland. Because of the interaction of the stormwater system with the problem areas in the City, a detailed stormwater basin plan to assess hydrological and hydraulic conditions throughout the system is warranted. This basin plan would determine the most cost effective and environmentally sound approach to alleviate the problem areas located in the City of Groveland. Presented below is a summary of the City of Groveland problem areas, and preliminary recommendations, which need to be verified with the recommended basin plan, for alleviating the stormwater problems. GRl - Groveland High School Problem Summary Ponding of runoff frequently occurs in a depressional area which is part of the schoolyard located northwest of intersection of Parkwood Street and State Road 33 (SR 33). No reports of runoff entering surrounding buildings has been recorded. As the depressional area stages up, it discharges into a 36" diameter reinforced concrete pipe (RCP) running southeasterly into a roadside ditch along SR 33. This ditch outfalls into a canal system beginning on the east side of SR 33 through a 2 feet high by 4 feet wide box culvert. No reports of road overtopping have been recorded. The use of the physical education facilities located in the problem area is limited until the runoff infiltrates into the underlying soil. Recommended Capital Improvements. Regrade the schoolyard with provisions for a swale outfalling into a retention/detention pond with a control structure to detain and treat runoff from the ponding area prior to discharging to the existing 36" diameter RCP . Conceptual Probable Cost Estimate. Capital costs are estimated to GR2 - Gadson Avenue Problem Summary A 36" diameter RCP passing under Gadson Avenue north of its intersection with Parkwood Street is experiencing erosion problems at both the entrance and exit of the culvert. This is evident due to the lack of an established uniform vegetative cover on the embankments. The two-lane road appeared structurally sound at the time of the site visit, but the potential exists for additional deterioration of the embankment to occur if the road is overtopped. This can produce structural damage to the road which could potentially endanger public safety. Recommended Capital Improvements. Installation of concrete headwalls at both the entrance and exit of the culvert, construction of erosion control at the downstream end, and the placement of sod on the eroded embankment. Conceptual Probable Cost Estimate. Capital costs are estimated to be $9,000. GR3 - Baldwin Avenue Problem Summarv Located on Baldwin Avenue south of SR 50, a 30" diameter corrugated metal pipe (CMP) is experiencing erosion problems at the downstream end of the culvert which does not have an established uniform vegetative cover on the embankment. The upstream embankment has adequate vegetation. The two-lane road appeared structurally sound at the time of the site visit, but the potential exists for additional deterioration of the embankment to occur if the road is overtopped. This can produce structural damage to the road which could potentially endanger public safety. Recommended Capital Improvements. Preliminary analyses indicate 0.5 feet of overtopping of the road during the 25-year, 24-hour storm event. In order to increase culvert size, treatment of upstream area would be required for a permit. The cost of such treatment would be prohibitive due to wetland constraints. This makes the installation of larger or multiple culvert(s) unlikely. Therefore, it is recommended that the existing 30" CMP be replaced with a 30" diameter RCP with concrete headwalls, erosion protection at both the entrance and exit, and approximately 2 ac-ft of off-line detention storage upstream to lower upstream flood stages. To protect the integrity of the roadway for flood conditions, the embankments should be re-graded to no steeper than 4H:lV and sodded. Conceptual Probable Cost Estimate. Capital costs are estimated to GR4- Sampey Road Problem Summary Located on the north side of SR 50, just downstream of the Baldwin Avenue Problem Area, two 4 feet high by 8 feet wide concrete arch culverts experience an increase in backwater elevations caused by clogging with vegetation. The problem is reported to occur frequently and is remedied by removal of the aquatic vegetation. This provides an increase in the level of service of the facility by restoring the capacity of the culverts and consequently, mitigates upstream flooding through the reduction of backwater elevations. Recommended Capital Improvements. Preliminary analyses indicate that the two culverts passing under Sampey Road and the two 6-10 culverts passing under SR 50 in between Sampey Road and Baldwin Avenue, have adequate capacity to convey the 25-year and 24-hour storm event without overtopping of the roadways. Therefore, the only capital improvements recommended are for erosion control. Armorform is recommended to be placed at the entrances and exists of the culverts passing under SR 50 and Sampey Road. Increased maintenance, at least on a quarterly basis, is recommended during the growing season. Conceptual Probable Cost Estimate. The capital costs for erosion control improvements are estimated to be $10,000. GR5 - Mount Pleasant Road Problem Summary Overtopping has been reported on Mount Pleasant Road at a depressional area (Bonnet Strand) located west of Lake David. Two 36" diameter culverts serve as an outfall for Bonnet Strand which receives discharges from Lake David. This area lies within flood prone areas as identified in Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps. The top of road elevation is approximately 6" above the top of the culverts. Embankments at both the upstream and downstream ends of the culvert appeared to be stable. There were no visible signs of structural deterioration of the road itself. Recommended Capital Improvements. Since this area is located in a FEMA flood prone area, a detailed hydrological and hydraulic evaluation is required to determine capital improvements. Therefore, no capital improvements can be assessed at this time. A recommendation for improvements in this problem area should result when a detailed basin plan is performed for this area. Conceptual Probable Cost Estimate. To be determined in a future basin plan. GR6 - Park Street Problem Summary Flooding has been reported immediately downstream of six 12" and two 36" CMPs located on Park Street, an extension of Ardmore Road, west of its intersection with Savage Street. The flooding has encroached on the surrounding residential area with no reports of runoff entering the homes recorded. The top of road elevation at this crossing is approximately 3" above the top of the culverts. Overtopping of the road at this location has been reported, which may result from backwater effects produced by downstream conditions. Embankments at both the upstream and downstream ends of the culverts appeared to be stable. There were no visible signs of structural deterioration of the road itself. Recommended Capital Improvements. Replace the eight CMPs with an equivalent capacity 3 feet high by 4 feet wide concrete box culvert as well as regrade the channel approaches and sod the embankments. Conceptual Probable Cost Estimate. Capital costs are estimated to be $25,000. GR7 - Mascotte Park Problem Summary Recently a clay core road with two 48" diameter CMPs was placed across the canal downstream of the area described in Problem GR6 above, within an adjacent park to the west. Reports of overtopping of the road have not been recorded. Even though the structural integrity was intact at the time of the site visit, the lack of embankment protection, such as a uniform vegetative cover, creates the potential for severe damage resulting from overtopping of the road, although this road is in a rural area. This occurrence would result in a reduction in the facility level of service. Recommended Capital Improvements. Regrade eroded slopes, install a concrete headwall at the entrance and exit of the culverts, and sod the embankments. Conceptual Probable Cost Estimate. Capital costs are estimated to be $23,000. City of Mascotte MA1 - Laurel Street Problem Summary Frequent flooding problems are occurring in a natural depression southeast of the intersection of Laurel Street and Woodland Avenue. Lacking a natural outfall, the depression floods the adjacent mobile home park. In the past, flood stages within the depression have approached critical levels (i.e. enter the surrounding mobile homes). A pump was used to pump runoff into Lake Jackson to the east. Lacking stormwater management facilities, the potential exists for home flooding. Recommended Capital Improvements. Convert the depression into a 2 acre wet detention pond (2.5 acre land purchase), install a control structure, and construct a 750 feet long ditch to the northeast, outfalling into Big Prairie. Flood waters will be controlled and discharges will receive water quality treatment. Conceptual Probable Cost Estimate. Capital costs are estimated to be $227,000. MX2 - Oaks Street Problem Summary Lacking stormwater facilities, a residential development located immediately southwest of Lake Jackson, is experiencing frequent flooding and erosion problems. The primary problem area runs from the intersection of Elizabeth and Oaks Street to the intersection of Oaks and Carol Streets to the east. From this point runoff flows in between homes outfalling into Lake Jackson. Erosion appears to be due to the lack of uniform vegetative cover along the streets and steep grades. Reports of runoff entering homes has not been recorded. Under current conditions, the occurrence of a major storm event could produce home flooding and severe erosion. Recommended Capital Improvements. Installation of a 24" RCP storm sewer system to convey runoff into a wet detention pond with controlled outflow into Lake Jackson. The contributing area of 8.3 acres will receive retrofit treatment. Conceptual Probable Cost Estimate. Capital costs are estimated to be $288,000. City of Mi~e0la MI1 - Chester Street Problem Summary Frequent flooding problems are occurring in a natural depression southeast of the intersection of Main Avenue and Chester Street to the east of Lake Mimeola. Lacking a natural outfall, the depression floods the adjacent residential area. The potential exists for extensive damages to the surrounding community resulting from a major storm event. A storm sewer system with a retention/detention pond outfalling into Lake Mimeola would mitigate flooding. Due to a shortage of undeveloped land in this area on which to construct the pond, the above alternative may be abandoned in favor of an exfiltration trench system. The problem area is approximately 25 feet above the Lake surface and consists of Type "A" soils, making the trench a potential alternative. Recommended Capital Improvements. Installation of a combined storm-sewer/exfiltration system to treat and convey flow to Lake Mimeola. The 4.2 acre contributing area would all receive treatment. Conceptual Probable Cost Estimate. Capital costs are estimated to be $88,000. MI2 - Washington Street Problem Summary A depression located on the south side of Washington Street in front of a strip mall located between Disston Avenue and U.S. Highway 27 is experiencing flooding problems due to inadequate stomter management facilities. The existing facilities consists of 12" diameter storm sewer with three inlets outfalling into a ditch running southerly along U.S. Highway 27. A site investigation revealed that the existing system was completely clogged. Maintenance efforts to clean the system have been unsuccessful. Ponding with depths up to approximately three feet along Washington Street and the mall parking lot have been reported. ~ecommendedCapital Improvements. Due to continuing problems with maintenance efforts, installation of a storm sewer system to treat and convey flow to the existing ditch running southerly along u.S. Highway 27 is required. Water quality treatment and peak flow attenuation can be achieved through the placement of a control structure in the ditch. Conceptual Probable Cost Estimate. Capital costs are estimated to be $175,000. City of Umatilla UM.1 - Seminole Street Problem Summary An existing swale and culvert system within a res.identia1development is experiencing erosion problems. This system runs west from the intersection of Seminole Street and Winogene Avenue to the intersection of Seminole Street and Ogden Avenue. At this point, the system runs to the south along Ogden Avenue outfalling into a pond located northeast of the intersection of Ogden Avenue and Ocala Street. Site visits indicate that the erosion is probably due to the lack of uniform vegetative cover and steep grades. Reports of road overtopping have not been recorded. A major storm event could result in extensive erosion along with road overtopping and possibly flooding of sur'roundinghomes. Recommended Capital Improvements. A closed storm sewer system was costed at the request of the City. This involves replacing the existing swale and culvert system with a storm sewer system and using the downstream pond system, with alterations, as a wet detention system. Conceptual Probable Cost Estimate. Capital costs are estimated to be $335,000. UM2 - Lakeside Avenue Problem Summary Frequent road flooding has been reported along Lakeside Avenue and Argyle Drive to the intersection with Trowell Drive. Located along the eastern shoreline of Lake Umatilla, the existing stomwater facilities consist of standard curb and gutter along with inlets discharging directly into the lake. The system serves approximately 210 acres of contributing area. A site investigation revealed that the existing system was completely clogged. Maintenance efforts to clean the system have been unsuccessful. During storm events, runoff ponds on the road until the curb is overtopped and then flows across a grassed buffer zone prior to entering the lake. This results in a reduction in the level of service of the road. Recommended Capital Improvements. Replace the four outlet structures with flumes and construct a treatment swale parallel to the lake. Size the swale to treat half the DCIA in the contributing area. This is all the retrofit possible unless soils data indicate that exfiltration can be used. Conceptual Probable Cost Estimate. Capital costs are estimated to be $133,000. Town of Astatula NO problem areas requiring capital improvements have been identified at this time. Town of Hmy-in-the-Hills NO problem areas requiring capital improvements have been identified at this time. Town of Lady Lake LL1 - Oak Grove SuWivision Problem Surmnarv A land-locked retention/detention pond located within the Oak Grove suWivision near the intersection of U.S. Highways 27 and 441 is experiencing flooding problems. The pond stage is regulated by a pump which delivers the runoff to an irrigation system for disposal through land application. The existing pump does not have the capacity to properly regulate the pond stage, resulting in flooding of the immediate area surrounding the pond. No reports of runoff entering adjacent homes has been recorded. Recommended Capital Improvements. A larger pump and pressure tank has been recommended by others to regulate the pond stage. Conceptual Probable Cost Estimate. Capital costs are estimated to be $30,000. Town of Montverde NO problem areas requiring capital improvements have been identified at this time. For water quality problem area identification, various federal, state, and local agencies were contacted for stomter quality data, reports, and studies. The FDER water quality reports are examples of studies which preliminarily address non-point source water quality. Very little non-point source, or stomter-related data exist; however, long-term declines in ambient water quality of lakes/streams coupled with identification of drain wells and sinkholes were used to identify potential non-point source impacts to surface and groundwater resources. Figure 6-2 shows known drain well and sinkhole locations, saltwater intrusion zones, and lakes/streams with a known decline in ambient water quality. Table 6-2 presents the location of these features with the respective basin and sub-basin. These are discussed in further detail below. CDM also evaluated non-point source pollutant loads from four major pollutants to twelve major lakes in the County to identify general magnitudes of non-point source pollutant loads. This analysis was presented in Section 5.0. Potential long-term water resource problem areas were identified by interviews, available water quality data analyses, non-point source loading analysis, saltwater intrusion trends, and facilities which discharge stomter to groundwater. These problem areas have been grouped as one category due to their complex nature. It is difficult to recommend specific structural solutions for these areas since detailed evaluations are required to properly alleviate the problems; however, in many cases, non-structural controls such as land use, development, or recharge requirements are a sound "first-stepu toward a comprehensive solution. The County's proposed Stormwater Management Ordinance addresses these issues. The following paragraphs list the types of problems and types of solutions that are recommended to be analyzed in detail during future phases of the County's Stornmter Management Program. 0z7=77-, 0z7=77-, miles ...... LEGEND e DRAIN WELL LOCATIONS A STREAM TO SINKHOLE PROBLEM LAKES SALTWATER INTRUSION TO FLORIDAN AQUIFER NOTE: FOR A LIST OF THE PROBLEM AREAS, REFER TO THE WATER QUALITY PROBLEM AREA WATER QUALITY PROBLEM AREAS en vironrnento1 engineers, scientists. ,p/anners. & management consultants CDM- FIGURE 6-2 n L - n 4 C ? 0 -uC, m 3- L 4 L 0 am om0 n I I a aJ aJ aJr I I YYYrC - V) I I m mm 0- 0 C, I I AAACV) r C I I YVV Yal c r C .r a aJ WWWrU aJ .r aJ Y Y YYYV)C Y V) I m- a mam 4 m- --- r A- A AAAOL A? ?-- OaJ r a +m a aa~a +aJ aJ E= E EEE E= =33 - II a a WWaJEV- a E r C ? 7 ?C CCC mu C n-? n nnn OO n- ."r- W 0 -r om o 000~3om aam LC m LL L LLL.QV LL LLL +'-'I L an a aaam an oon V)- 0 STREAM TO SINKHOLE TWO stream-to-sinkhole locations have been identified in Lake County. These are Wolf Branch Sink and the Shocklee Heights Area Sink (Figure 6-2). These are locations where flowing streams discharge directly into the Floridan Aquifer, which is the local drinking water supply. As a result, pollutants from urban runoff can enter the aquifer and contaminate it. In addition, lack of land use controls around the sinkhole can also allow other pollutant inflows from industry or septic tanks. Therefore, a treatment pond, located immediately upstream of the sinkholes, coupled with land use controls and conservation areas preservation, are sound approaches to control this problem. DRAIN WELLS There are eight drain wells in the County as identified by the USGS and interviews. These were shown in Figure 1-5. They are used for the following: two for lake level control, two for stormwater discharge, and four for heat pump return flow. Like sinkholes, drain wells allow stormwater pollutants to enter the Floridan Aquifer. Similar land use controls, and a detention pond system will help to mitigate potential aquifer contamination. The best solution for drain wells is to discourage, or even prohibit, their use. The lake level and stormwater discharge wells are recommended to be evaluated in the future phases of the Countyts Stomter Management Program to see if flood waters can be diverted to treatment areas rather than discharged into the aquifer or if upstream treatment facilities are warranted. The four heat pump return flow wells could be used for irrigation depending on the quality of the effluent. For all cases, interactions with the lori id an Aquifer should be limited to properly treated recharge and potable withdrawals. SALrnTER INTRUSION Saltwater intrusion to the Floridan Aquifer has been documented in the form of elevated chloride concentrations in the northeast portion of the County in the St. Johns River and Wekiva River basins. This is a very complex issue that is being considered by the SJRWMD as part of regional groundwater evaluations. Therefore, the County should pursue non-structural controls such as land use restrictions and recharge requirements until firm approaches are defined by the SJRWMD. W(E WATER QUALITY DECLINE Ambient water quality analysis by others and CDM indicate that several lakes are experiencing declines in water quality. As discussed earlier, Lake ~eauclair,Lake Dora, and Lake Griffin appear to have poor water quality, while Lake Eustis is borderline between fair and poor. The State of Florida SWIM Program is separately studying the complex problem of Lake Apopka. Solutions to these water resource problems will require long-term, detailed solutions. However, certain BMP options can be pursued sooner, such as the following: o When stormwater facilities are retrofitted or replaced in a given area, every effort should be made to provide retrofit treatment; o Septic tanks should be discouraged wherever regional sewer service is a viable option; and o Regulation of lake levels by keeping lakes high for dry season navigation and low for wet season flood control is the opposite of what is necessary to propogate wetland species, allow for littoral zone uptake of settlable pollutants, and promote fishery habitat. The regulation schedule for the chain of lakes is currently being restudied by the SJRWMD along with an accompanying socio-economic study by the University of Florida; these studies will allow the County to better understand the options for structural changes to the systems. 6.2.3 NON-PROBLEM FACILITIES Detailed hydrologic and hydraulic analyses, as performed in Watershed or Basin Plans, are required to properly evaluate capacity versus demand for facilities not associated with known problems. Stormwater facility capacity varies depending upon acceptable limits of flooding, facility condition (maintained versus non-maintained), and facility design parameters such as size or diameter, headwater versus tailwater relationships, length, slope, and friction/local loss coefficients. Facility demand will vary depending on design storm frequency, intensity, and duration, as well as land use imperviousness and initial hydrologic conditions (water table levels and degree of soil saturation). Flow (or demand) hydrographs, and peak flows, are generated for routing analysis through stormwater facilities. These routing analyses are accomplished through computer models, design nomographs, and/or hand calculations. For the problem areas in Section 6.2.1, this procedure was followed. Thus, to perform a thorough evaluation of capacity and demand for non-problem area stormwater structures in Lake County, a detailed hydrological and hydraulic assessment is required. This type of assessment is more involved than the planning type of assessment required for the State's Comprehensive Plan, and this studyfs requirements. However, at this planning level capacity versus demand can be evaluated for non-problem area facilities in the County by screening historic rainfall records for the rainfall gages previously identified in Section 3.0. These recent historic storms can then be compared with design storm frequencies, durations, amounts, and intensities to identify the minimum level of service provided in a given geographic area. This type of assessment is based on the County enforcing the proposed County Stormwater Ordinance, which requires that peak stormwater rates form a developed area be equal to or less than the peak stormwater rate prior to development. With the enforcement of said ordinance, Lake County will be provided with the same future level of service as currently exists in the County. Maxirmun storm amounts and intensities (where available) were identified for the more recent of these historic storms. able 3-3 showed the results for the historic storm analysis which indicate that facilities not associated with problems in the County are currently providing at least a 5-year frequency, 24-hour duration water quantity Level Of Service. The Clermont area is currently providing at least a 10-year Level of Service based on a recent 6.9 inch rainfall event. As stated previously, by the County enacting their Stormwater Management Ordinance, this level of service should remain for future conditions. A more detailed water quantity Level of Service analysis is recommended to be provided for each basin as future Basin Plans are performed. 7.0 COMPUTER MODEL COMPARISONS This section presents a comparison of water quantity and quality computer models, which the County may consider to implement to monitor future level of service and stornwater system impacts due to growth-related or system alternations impacts. 7.1 WATER OUANTITY MODELS 7.1.1 WATER QUANTITY MODEL COMPARISON ITEMS Water quantity computer models which could be used by the County were compared based upon the following items: o County goals, perspectives, and training (e.g., level of detail, model updating, permitting needs) o Model credibility - Technically correct with demonstrated performance - Peer acceptance - Ability to simulate realistic conditions o Public domain o Suitable for microcomputer applications o Flexible and adaptable o User-friendly within the limits of data constraints o Quality of documentation o Maintenance of model by model developers - User groups - Periodic model updating and enhancements o Applicable to the study area - Represents key elements of stormwater management system (irregular and/or regular cross-sections, culverts, storage elements, boundary conditions, etc.) - Calculates flows, velocities, and water surface elevations - Handles backwater and surcharged pipe flow conditions - Handles flow reversals and interconnections - Can perform dynamic simulations of watershed-wide impacts - Can represent small basins (tens of acres) as well as large basins (hundreds to thousands of acres) 7.1.2 AVAILABLE WATER QUANTITY MODELS The following paragraphs briefly discuss the water quantity model packages considered. Key excerpts are taken from the respective mgdel handbooks: o The USACOE Hydrologic Engineering Center (HEC) Models 1 and 2 "The HEC-1 model is designed to simulate the surface runoff response of a river basin to precipitation by representing the basin as an interconnected system of hydrologic and hydraulic components. Each component models an aspect of the precipitation-runoff process within a portion of the basin, commonly referred to as a sub-basin. A component may represent a surface runoff entity, a stream channel, or a reservoir. Representation of a component requires a set of parameters which specify the particular characteristics of the component and mathematical relations which describe the physical processes. The result of the modeling process is the computation of streamflow hydrographs at desired locations in the river basin." "The HEC-2 model is intended for calculating water surface profilesfor steady gradually varied flow in natural or manmade channels. Both subcritical and supercritical flow profiles can be calculated. The effects of various obstructions such as bridges, culverts, weirs, and structures in the flood plain may be considered in the computations. The computational procedures is based on the solution of the one-dimensional energy equation with energy loss due to friction evaluated with Manning's equation. The computational procedure is generally known as the Standard Step Method. The program is also designed for application in floodplain management and flood insurance studies to evaluate floodway encroachments and to designate flood hazard zones. Mso, capabilities are available for assessing the effects of channel improvements and levees on water surface profiles. Input and output units may be either English or Metric." o The USDA SCS Technical Release (TR) 20 and TR-61 Models "The TR-20 computer program assists the engineering in hydrologic evaluation of flood events for use in analysis of water resource projects. The program is a single event model which computes direct runoff resulting from any synthetic or natural rainstorm. There is no provision for recovery of initial abstraction or infiltration during periods of no rainfall. It develops flood hydrographs from runoff and routes the flow through stream channels and reservoirs. It combines the routed hydrograph with those from tributaries and computes the peak discharges, their times of occurrence, and the water surface elevations at any desired cross section or structure. Any one of the above items can be printed out as well as discharge hydrograph elevations, if requested. The program provides for the analysis of up to nine different rainstorm distributions over a watershed under various combinations of land treatment, floodwater retarding structures, diversions, and channel work. Such analysis can be performed on as many as 200 reaches and 99 structures in any one continuous run. The program uses the procedures described in the SCS National Engineering Handbook, Section 4, Hydrology (NEH-4) except for the reach flood routing procedure." "TR-61, commonly called WSP2 (Water Surface Profile 2), can aid in &aGtermination of flow characteristics for a given set of stream and flood-plain conditions. More specifically, it can compute water surface profiles in open channels. The program also can estimate head losses at restrictive sections, including roadways with either a bridge opening or culverts." o Advanced Engineering Technology (AET) Santa Barbara Urban Hydrograph (SBUH), SCS Unit Hydrograph (SCS UNIT), and Interconnected Pond Routing (adICPR) Models "The SBUH package is used to generate stormwater runoff hydrowphs. Up to 200 sub-basins can be simulated simultaneously with an option to compute and store composite hydrographs. SBUH uses the Soil Conservation Service (SCS) curve number for infiltration losses and incorporates directly connected impervious areas. Rainfall is based on non-dimensional mass curves stored on disk files or keyed in directly." "SCSUNIT is a program that uses the SCS (Soil Conservation Service) Unit Hydrograph Method to compute up to 100 runoff hydrographs at a time for small watersheds. Rainfall excess is computed using the SCS Curve Number and infiltration formula. It is then applied to a unit hydrograph (based on basin characteristics, and shape factor) to obtain runoff throughout the storm duration. The program requires physical input data for each basin as well as control data that are applied to all basins for which hydrographs are to be computed. Basin Shape Factors (and their corresponding unit hydrographs) can be selected from a standardized table, or input directly by the user. Standardized non-dimensional rainfall distributions can be input in similar fashion. Therefore, the program keeps input data to a minimum, resulting in ease of use and a reduction in chances for erroneous data transcription. Outputs from the program are varied, providing for flexibility in previewing data before printing and for structured easy-to-use hardcopy. SCSUNIT also includes an output routine that loads summary and hydrograph ordinates to a disk file for use by other programs." "adICPR is an interactive software package designed to route flood h-raphs through single pond systems as well as multiple interconnected ponds, lakes, or reservoirs. The input and edit routines allow for easy construction of complex networks, including both dendritic and looped systems. Factors such as time-variable tailwater conditions, submergence flow reversal and multiple boundary conditions are integrated into the solution algorithm. Pond connections can be made with sharp and broad crested weirs; gates and orifices; circular, elliptical, arch and box culverts; trapezoidal and parabolic channels; risers (i.e., weirs in series with either culverts or channels); and, rating curves. Physical parameters of individual connections are simply keyed in, with complicated hydraulic computations performed internally by adICPR.It o CDM RUNOFF CDM RUNOFF is a modified version of the RUNOFF Block of the USEPA Stormwater Management Model (SWMM) by Camp Dresser & McKee (CDM, 1970 and June 1988). The program simulates the rates of runoff developed from subareas using a kinematic wave approximation. Hydrologic routing techniques are then used to route the overland flows through the pipe, culvert, channel, and lake network as required. Program results can be saved for input to the EXTRAN Block of SWMM to perform hydraulic routing in downstream reaches. RUNOFF was originally developed in 1970 as part of the original USEPA Stormwater Management Model (SWMM). The program has been applied many times since its inception and has gained world-wide acceptance. Over the years, the program has undergone many changes and modifications although the main formulations and calculations remain mostly unchanged from the original codes. Program modifications were performed by CDM to streamline program functions and expand channel/lake routing capabilities for use in stormwater master plan studies. Many of the modifications made to the code are derived from a version of RUNOFF previously developed by CDM (MSSM, 1986). A more complete documentation on the model's background and theory can be found in the USEPA SWMM Userts Manual. The basic overland flow and channel routing calculations remain unchanged in this version of RUNOFF, the program will accept input data sets for the USEPA SWMM RUNOFF program. CDMtsversion of RUNOFF has the following added features: - Compatibility with IBM PCs and other IBM compatible microcomputers; - Runoff hydrograph routing through lakes; - Runoff hydrograph routing through channels with irregular cross sections; - Ability to specify a maximum volume of rainfall which can infiltrate into the soil (total soil storage in inches); - Resizing of pipes and trapezoidal channels to convey peak flows ; - Diversion of surcharged flows to relief pipes/channels; - Input of constant baseflow to pipes, streams, and channels; - On-screen printout of the simulation percentage of completion; and - Summary tables of peak subarea runoff and other modifications to program output. 0 CDM EXTRAN CDM EXTRAN is a modified version of the EXTRAN BLOCK from EWMM 111.0. CDM revisions were used as the basis for the SWMM IV EXTRAN Block, (CDM, 1975 and August 1988). EXTRAN is a hydraulic flow routing model for open channel and/or closed conduit systems. It uses a link-node (conduit-junction) representation of the drainage system in an explicit finite difference solution of the equations of gradually varied, unsteady flow. EXTRAN receives hydrograph input at specific junctions by disk file transfer from a hydrologic model such as RUNOFF or TR20, and/or by manual input. The model performs dynamic routing of stormwater flows through the major storm drainage system to the points of outfall to the receiving water system. The program will simulate branched or looped networks, backwater due to tidal or non-tidal conditions, free-surface flow, pressure flow or surcharge, flow reversals, flow transfer by weirs, orifices and pumping facilities, and storage at on-line or off-line facilities. Types of conduits that can be simulated include circular, rectangular, horseshoe, elliptical, and baskethandle pipes, plus trapezoidal or irregular channel cross-sections. Simulation output takes the form of water surface elevations and discharges at selected system locations. mTR?iN was developed for the City of San Francisco in 1973. At that time it was called the San Francisco Model or the WRE Transport Model. In 1974, EPA acquired this model and incorporated it into the SWPlM package, calling it the Extended Transport Model - EXTRAN - to distinguish it from the TRANSPORT Module developed by the University of Florida as part of the original SWMEl package. Since that time, the model has been refined, particularly in the way the flow routing is performed under surcharged conditions and in large open channel networks. Also, much experience has been gained in the use and misuse of the mode 1. Several enhancements to EXTRAN have been achieved since SWMM 111.0 was released in 1981. These are summarized as follows: - Input and simulation of channels with irregular cross-sections from select HEC-2 data cards; - Variable stage-area junctions; - pump curves; - ~ifferentboundary conditions at each system outfall; - "Hot-start" input and output from binary files; and - On-screen printout of the simulation percentage of completion. In addition, minor changes to several algorithms were performed for program efficiency and accuracy. All changes were structured to allow the model to read input data sets developed from SWMM 111.0. o HSP-F The Hydrologic Simulation Program - FORTRAN (HSP-F) HSP-F is a comprehensive package program designed for continuous simulation of watershed hydrology and receiving water quality. HSPF was developed from the Hydrocomp Simulation Program (HSP) which includes the Agriculture Runoff Management (ARM) model (Donigian and Davis, 1978) and the Non-Point Source (NPS) model (Donigian and Crowford, 1976) for runoff simulation, and incorporates the SERATRA model (Onishi and Wise, 1982) for the sediment transport, pesticide decay, sediment-contaminant partitioning, and risk assessment. The model is fully dynamic and can simulate chemical behavior over an extended period of time, using a constant time step selected by the user. HSPF includes time series-based simulation modules (PERLIND, IMPLND and RCHRES), and utility modules (COPY, PLTGEN, DISPLY, DURANL, and GENER). The simulation (application)modules include mathematics for the behavior of processes which occur in a study watershed. The watershed is divided into three segments which include pervious land, impervious land, and a receiving water system (i.e., a single reach of an open channel or a completely mixed impoundment). The module PERLND simulates the pervious land segment with homogeneous hydrologic and climatic characteristics, including snow accumulation and melt, water movement (overland flow, interflow and groundwater flow), sediment erosion and scouring, and water quality (pesticides, nutrients). The IMPLND module simulates the impervious land segment where little or no infiltration occurs. The IMPLND processes include snow and water movements, solids, and water quality constituents. The module RCHRES simulates the segment of receiving water body, including hydrologic behavior, conservative and non-conservative constituents, temperature, sediments, BOD and DO, nitrogen, phosphorus, carbon, and pH. The utility modules perform "house-keeping" operations, designed to provide the user flexibility in managing simulation inputs and outputs. For example, the COPY module manipulates time series. 7.1.3 WTER QUANTITY MODEL RECOMMJWDATIONS Table 7-1 shows the comparison of the available water quantity models based on the previously identified screening items. Based upon the model screening and CDMfs experience, CDM recommends the use of the RUNOFF and EXTRAN models for future water quantity evaluations. It should also be noted that the methods used in the RUNOFF/EXTRAN package will utilize the following methodologies to ensure consistency with other accepted approaches which may be applied by various engineers during permit reviews : o Runoff excess computations based on the Horton equation with total soil storage constraints which can be related to SCS curve numbers (similar to TR-20 and HEC-1); o DCIA evaluated as a separate flow surface (similar to HEC-1 and SBUH ) ; o Overland flow routing by a kinematic wave with Manning's equation coefficients (similar to HEC-1); o Simple, hydrologic routing in RUNOFF by the storage-indication method (similar to TR-20 and HEC-1); o Simple, channel routing in RUNOFF by a kinematic wave approach (similar to TR-20); TABLE 7-1 WATER QUANTITY MODEL SCREENING MATRIX DIRECTLY BASE 6lOR NON-PDINT CLOSED REGULAR 6 MULTIPLE VARIABLE FLOW MASS. PRINTS MULTIPLE CONNECTED DRY SOURCE CONDUITS IRREGULAR HYDRAULIC STAGE- REVERSALS ENERGY. 6 FLOUS. REPORTS TOTAL MOOEL HYDROGRAPH MULTIPLE IMPERVIOUS PERVIOUS WEATHER POLLUTION 6 CROSS- BOUNDARY AREA 6 INTER- MOMENTUM STAGES, 6 INUNDATED CONTINUOUS NUMBER PACKAGE INFLOWS HYETOGRAPHS AREAS AREAS FLOWS CAPABILITY BRIDGES SECTIONS CONDITIONS JUNCTIONS CONNECTIONS SOLUTIONS VELOCITIES AREA CAPABILITY CDM RUNOFF1 YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES 15 EXTRAN SCS TR-20/ YES YES NO YES YES NO YES YES NO YES NO NO NO NO NO 7 TR-61 USACOE YES YES YES YES YES NO YES YES NO YES NO NO YES NO NO 9 HEC-11 HEC-2 AET SCSUNITI YES YES YES YES YES NO YES YES YES YES YES NO YES NO NO 11 SBUHladICPR HSP-F YES YES YES YES YES YES YESlNO YESlNO NO YES NO NO YES NO YES 10 o HEC-2 irregular cross-section format capability in both RUNOFF and EXTRAN; and o Variable stage-area relationships in both RUNOFF and EXTRAN. 7.2 WATER QUALITY MODELS NON-POINT SOURCE (NPS) WATER QUALITY MODEL To evaluate non-point pollution loading targets and associated management options, it is important that the planning tools (i.e., water quality models) be compatible with the complexity of the water quality problems, important management issues, and the available water quality monitoring database. A non-point pollution management plan is not necessarily more technically defensible just because it relies upon a more complex water quality model, particularly, if the model complexity is inconsistent with the management issues, or there is insufficient water quality monitoring data available to calibratefierify model parameters and to demonstrate its credibility to decision-makers. In fact, the less complex model which is compatible with the available data and the level of accuracy required to compare watershed management options is usually the preferable planning tool. If the instream travel times are long enough to produce significant decay and transformation of non-point pollution loadings before they reach the critical receiving water, we generally recommend the use of non-point pollution loading models which include instream transport. If instream travel times are short, the recommended model need not have instream transport capability. In Lake County, the ultimate model package used for future evaluations should have the capability to route pollutants through lakes since much of the County is comprised of lakes. Further evaluation of data availability and adequacy is required to recommend a master planning water quality model in Lake County; however, CDM has developed a Non-Point Source (NPS) Spreadsheet model which can be used with pollutant loading factors to screen overall trends (annual pollutant loads). For this report, the NPS spreadsheet model was used to evaluate ultimate water quality model recommendations in Lake County (see Section 5). The following paragraphs provide a brief description of the CDM-WS model. NPS SPREADSHEET MODEL The NPS Spreadsheet model simulates annual non-point pollution loadings from local rainfall statistics. The model relies upon Event Mean Concentration (EMC) factors for different land use categories to calculate pollution loadings. Because this model is spreadsheet-based, it can be quickly applied to screen the pollution loading in order to identify and rank water quality problem areas by priority. For future water quality evaluations in Lake County, the Spreadsheet model could be used to screen a series of management options to determine which options warrant further evaluation through the use of a continuous water quality model which includes instream transport capabilities. In this manner, the number of management options can be reduced to a reasonable number for detailed study. 8.0 LEVELS OF SERVICE Stormwater management has become a complex community issue. In the past, ditching and draining to convey stormwater away from development was the accepted practice and allowed access to much of Florida. Over the years, adverse impacts to fisheries, scenic areas, and wildlife habitats have enlightened accepted approaches to manage stormwater. Stormwater management now involves storage, conveyance, recharge, conservation, and treatment aspects along with proper timing, durations, levels of flooding, and nutrient releases for natural areas or wetlands to ensure a comprehensive management approach to what is a local, State, and Federal issue. Lake County is similar in characteristics to other communities regarding stormwater service. Certain County, City, and private stormwater management systems provide a degree of flood protection to homes and streets, and a degree of treatment of the runoff prior to discharge to receiving waters. As with other communities, stormwater systems were constructed in a "piece-meal" manner, (i.e., without evaluating overall system performance) and with little regard to the treatment of stormwater. To properly implement a stormwater management system, a detailed stormwater master plan is required and levels of service for the stormwater structures need to be identified. Proper levels of service (LOS) decisions for water quantity (flooding) and water quality protection are essential because they establish the intent of public safety and agency involvement, and set the goals for the County to satisfy. WATER QUANTITY The water quantity LOS decision will drive the size and cost of stormwater facilities and is an essential decision within the SWMP. Figure 8-1 shows examples of various water quantity levels of service within a developed area. For example, Class D provides for flood protection of first-floor elevations, evacuation routes, and arterial roads, while Class C provides CLASS A ROADWAY WIDTH (W) CLASS B CLASS C CLASS D < FIRST FLOOR ELEVATION control of flood waters to less than 0.5 ft over the arterial/evacuation road crams. For urban sub-basins, it is likely that a diminishing return for public expenditures will occur sooner than for new developments due to space constraints and low-lying first-floor and road elevations. The water quantity LOS also requires decisions regarding design storms. This is because stomwater structure design is dependent upon the storm frequency and duration. The following storm events are recommended to be used for stomwater facility design: Storm Storm Frequency ( YR) Duration (HR) Facility Type 2 2 4 Retentionpetention Basins 24 Retentionpetention Basins and Storm Sewers 2 4 Retentionpetention Basins, Canals, Ditches, and Culverts 25 96 Landlocked Areas 50 24 Bridges 24 First Floor Elevation Must be 18" or Above These storm events and facility types are consistent with the County's draft Stormwater Management Ordinance. Recommended rainfall distribution, amounts, and intensities to be used for basin-specific design storm evaluations as part of subsequent permitting and stornrwater program phases were previously presented in Table 3-1. These values are based on an SCS Type 111 distribution (formerly called the Type II-modified) and SJRWMD Technical Publication SJ 88-3. Values for design events not included in this publication were derived by a least squares regression of provided values. 8.2 WATER QUALITY Water quality LOS is generally based on "first flush'' abatement of pollutants for new developments (Figure 8-2). Retrofit LOS is often established separately due to space and financial constraints. In general, water quality retrofits are required if flooding solutions are implemented. For this reason, achievable water quality LOS for retrofit facilities will be case-specific. For subsequent Stormwater Management Program Phases, priorities for pollutant loads should also be considered in the eventual choice for water quality LOS. 8.3 SUMMARY LOS should be established to be consistent throughout the County; however, it is often difficult to apply new development criteria to existing problem areas. The problem area solutions in Section 6.0 attempt to provide new development LOS wherever possible. The historic storm analysis in Section 3.0 indicates that facilities not associated with problems in the County are currently providing at least a 5-year frequency, 24-hour duration water quantity level of service. The Clermont area is currently providing at least a 10-year level of service based on a recent 6-9 inch event. Therefore, existing systems should be retrofit to provide at least a Class D 5-year LOS consistent with the historic storm analysis in Table 3-3. New development LOS is recommended to satisfy the requirements of the County's Draft Stormwater Management Ordinance (Class D, 100-year LOS). Where possible and with reasonable financial constraints, existing systems should be retofit to the Ordinance requirements as well. Participation by the public and the regulatory agencies is critical to the implementation process. The public must decide on the LOS they desire and are willing to fund. In urban areas, trade-offs of flood protection and water quality enhancement for park alterations may need to be considered. The regulatory agencies need to consider alternative solutions and balance net positive effects of the project versus potential negative impacts. 5 m m5 L o0 $ r :3 I C) m CONTRIBUTING AREA 3 3 ? 5 9 2 e; 3: 9 a G 3 3 5' (D (D :4 0 *THE "FIRST-FLUSH" OF RUNOFF 8 :: 2 5 FROM THE CONTRIBUTING AREA 2 2 RECEIVES TREATMENT PRIOR TO 9 a c; .T DISCHARGE TO RECEIVING WATERS DEPENDING ON TREATMENT TYPE. 0 8.4 PRIORITIZATION Priorities are necessary to ensure that acute needs are dealt with as soon and efficiently as possible. This section presents priorities for solutions to problem areas identified to-date, and priorities for basin studies within the Stormwater Master Plan. 9.0 RECOMMENDATIONS Presented below is a summary of the non-structural and structural improvements recommended for Lake County. These recommendations will allow the County to commence the implementation of a Stomter Management Program to protect public safety, protect groundwater recharge, properly manage wetlands, and enhance water quality in Lake County, while allowing the County to meet regulatory agencies1 criteria. on-structural improvements are items which do not require physical improvements, such as regulations or actions required to implement the improvements to the County's stomwater management system. Non-structural improvements include the setting of goals, objectives, and policies (per the State's 95-5, FAC criteria). These include action items, stomwater regulations and ordinances, and maintenance practices. Each of these non-structural improvement categories is discussed below. 9.1.1 GOALS, OBJECTIVES, AND POLICIES In coordination with this report, and per the State's 95-5, FAC requirements, Lake County has developed a set of Stomwater Management goals, objectives, and policies. The County's Stomwater Management goal, as stated in the County's Comprehensive Plan, is: "Lake County shall provide sound stomwater, surface water, and groundwater resource management to prevent flood damage and protect water quality to ensure the safety and well being of the citizens of Lake County. " In order to fulfill this goal, the County identified four objectives and established 37 policies to follow. The four objectives are presented below. OBJECTIVE 1: CORRECT EXISTING DEFICIENCIES. Lake County shall identify and correct existing facility deficiencies on a priority basis. The County shall address known problems such as flooding and degradation of surface and groundwater quality. OBJECTIVE 2: GUIDE FUTURE DEVELOPMENT. Lake County shall manage and coordinate its stormwater review and implementation process to address the needs of future development. OBJECTIVE 3: MAXIMIZE FACILITY USE AND DISCOURAGE INEFFICIENT LAM) -USE. Lake County shall maximize the use of existing stormwater management facilities and available capacity, and promote efficient land utilization through the implementation of appropriate technology. OBJECTIVE 4: PROTECT THE FUNCTIONS OF NATURAL FEATURES. Lake County shall 1) minimize the occurrence of flooding that is a threat to human health or property; 2) identify and prohibit drainage wells; and 3) improve its ability to manage stormwater so as to minimize the degradation of surface water in order to protect the functions of natural features. The 37 policies required to be implemented by the County to satisfy the four objectives are contained in Appendix A (Lake County's Stormwater Sub-Element, Chapter V1-C, of the County's Comprehensive Plan) of this report. 9.1.2 STORMWATER MANAGEPENT REGULATIONS AND ORDINANCES Lake County is currently in the process of adopting a Stormwater Ordinance. The draft ordinance provides the mechanism for the County to enforce its stormwater management objectives in order to fulfill the stormwater goal. As presented in Section 4.0, the draft Stormwater Management Ordinance will be the most comprehensive stormwater ordinance in Lake County, when compared with other municipal ordinances within Lake County. The County's proposed ordinance defines required levels of service for stormater facilities, provides design criteria to be followed in implementing stormwater improvements, and requires the identification of a suitable entity to perform maintenance on the stomter facilities. Appendix C presents a copy of the County's draft Stomter Management Ordinance. Based on these merits, it is recommended that the County adopt its draft Stomter Management Ordinance. Local cities and towns within the County are encouraged to adopt similar ordinances. As presented in Section 4.0, the cities and towns within Lake County do not have as stringent stormwater management regulations as those currently being proposed by Lake County. 9.1.3 MAINTENANCE PRACTICES Proper operation and maintenance of stormwater management facilities is essential to the facilities providing the design levels of service. These practices are also usually specific to a given county or city. For this reason, operation and maintenance practices were evaluated based on interviews with County and various City staff regarding regular practices. Currently, County facilities are maintained on an as-needed basis as time and manpower allow. Likewise, the cities in the County perform maintenance on an as-needed basis. The problem with this approach is that silt, debris, and some harmful vegetation can accumulate to the point where a problem that could have been avoided occurs during a large storm. Thus, it is recommended that a regular maintenance schedule should be established and budgeted for each year by the County. Once implemented on a regular basis, this maintenance program would not only improve the consistency of level of service, but would also demonstrate to the citizens that their tax dollars are working for them. Table 9-1 outlines recommended frequencies for maintenance by facility type. Based upon these recommended maintenance practices, a cost estimate to provide this level of maintenance was performed. Table 9-2 presents the results of the cost estimate evaluation. As shown in Table 9-2, approximately $1,775,000 of annual expenditures are estimated to be required. TABLE 9-1 RECOMMENDED MAIN!ElWNCE FREQUENCIES BY FACILITY TYPE FACILITY TYPE MAINTENANCE FREQUENCIES 1. Storm Sewers and Culverts Annual inspections and silt/debris removal at least every two years. 2. Retentionpetention Ponds Annual structure inspection. Silt removal every four years. Mow grass two or three times annually. 3. Bridges Annual inspection for structural stability and erosion. 4. Canals, Ditches, and Swales Annual inspection for erosion and mowing two or three times annually. Removal of silt and sediments at least every five years. TABLE 9-2 ANNUAL MAINTENANCE COSTS Okl awaha MI thlacoochee Uetlva St. Johns Ktss lmmee COUNTY Rlver Basln Rlver Basln Rlver Basln elver Basln Rlver Basln TOTAL nalntenance Type ($1 ($1 ($1 ($1 ($1 Swale nalntenance (sedlment removal every 5 yearsl Culvert natntenance removal every 5 yearsl Culvert Repl acement (replace every 30 years) (3 3-man crews) Equlpment Repl acement (see below) BASIN TOTAL ($1 I COUNTY TOTAL ($1 EQUIPMENT REPLACEMENT COSTS 1 Ammortlzed Equ 1pmen t Number Unlt Cost Cost Costs ($1 ($1 ($1 Gradall 2 165.000 330.000 53.700 Front End Loader 2 80.000 160.000 26.000 Backhoe (on tracks) 2 165.000 330.000 53.700 Backhoe (on tlres) 4 80.000 320.000 52.100 Tandem Trucks 10 60.000 600.000 97.600 Flat-Bed Trucks 4 50.000 200.000 32,600 Drag1 lne 1 200.000 200.000 32.600 Vacuum Truck 2 150,000 300.000 48.800 2.440.000 397,100 I I I (1) Assumes replacement of equipment every 10 years; average Interest rate of 101. 9.2 STRUCTURAL IMPROVEMDJTS Structural improvements are physical improvements to the County's stomwater management system, along with the associated evaluations, field information, and investigations required to implement the improvements. 9.2.1 PROBLEM AREA IMPROVEMENTS Table 9-3 presents a summary of the problem areas identified in Section 6.0. The summary includes a probable cost for the recommended improvements and a preliminary categorizing (as serious or nuisance based on the definitions in Section 6.0) and ranking of the problem areas. The preliminary categorizing of the problem areas is defined as: o High Priority (Serious) - potential to endanger life and/or potable water supplies; o Medium Priority (Serious) - potential to endanger property and/or environmentally vital areas; and o Low Priority (Nuisance) - potential to cause minor damage to property, inconvenience, or unsightliness. Of the 19 problem areas, 11 have been identified as high priority, 8 as medium priority, and none as low priority. The projects are listed in a preliminary ranking based on available information regarding severity of the problem and the need for immediate solutions. The phased CIP should consider land acquisition first, especially around Wolf-Branch sink and the drainwells not associated with heatpumps. As shown in Table 9-3, the total cost to implement the structural improvements is projected to be $1,696,000. As stated previously in Section 6.0, prior to implementing these improvements it is recommended that detailed hydrologic and hydraulic evaluations should be performed. TABLE 9-3 PROBLEM AREA SUMMARY Preliminary Recommended Capital (1 Improvement Problem Area Ranking Priority Cost($) LC1 - Astor Area ' 4 M Sub-Basin Study (2) LC2 - Lake Yale Dike / 18 M Erosion Protection 16,000 LC3 - Wolf Branch Road / 3 H Widen We i r 31,000 LC4 - Wolf Branch Sink ' 1 H Sub-Basin Study (2) LC5 - Shocklee Heights Sink / 2 H Sub-Basin Study (2) GR1 - Groveland High School 5 M Swales & Detention 256,000 GR2 - Gadson Avenue d 11 H Install Headwalls 9,000 GR3 - Baldwin Avenue 8 H 30" RCP & Detention 49,000 GR4 - Sampey Road 19 M Erosion Protection 10,000 GR5 - Mount Pleasant Road / 10 H Sub-Basin Study (2) GR6 - Park Street J 9 H 3'x4' CBC 25,000 GR7 - Mascotte Park 1 17 M Install Headwalls 23,000 MA1 - Laurel Street 1 7 H Detention Pond 227,000 MA2 - Oaks Street 1 13 M 24" RCP & Detention 288,000 MI1 - Chester Street / 16 M Exfiltration Trench 88,000 MI2 - Washington Street 14 M Closed Storm Sewer & 176,000 Detention UM1 - Seminole Street / 12 M Closed Storm Sewer & 335,000 Detention UM2 - Lakeside Avenue ./' 15 M Flumes & Swales 133,000 LL1 - Oak Grove Subdivision 6 M Larger Pumping System 30,000 & Sub-Basin Study (2) TOTAL $$,696,000(~) Priorities were assigned as the following: High Priority (H) - potential to endanger life due to depth of inundated and/or facility failure (e.g., evacuation route or arterial road); Medium Priority (M) - potential to endanger property and/or environmentally vital areas; and Low Priority (L) - potential to cause limited damage to property, inconvenience, or unsightliness. (2) Included in Future Basin Study Recommendations (Section 9.2.3). (3) The total costs identifiable at this time. 9.2.2 UNKNOWN PROBLEM AREA IMPROVEMENTS Identification of unknown problem areas is difficult to ascertain at this planning level. Potential water quantity problem areas can only be identified through detailed hydrologic and hydraulic investigations, which are performed during basin studies. However, at this planning level, a conceptual analysis can be performed to estimate the cost of potential retrofit improvements which would provide for the treatment of stormwater in areas where no treatment currently exists. The retrofit improvements would reduce existing pollutant loads to receiving waters in Lake County. The retrofit improvements would provide treatment of the directly connected impervious areas (DCIAs) in Lake County. Since the majority of pollutants is carried in the first inch of runoff from the DCIA, the treatment of this volume would provide for a cost-effective treatment facility in urbanized areas, which is where a majority of the areas are located. For this conceptual analysis, the retrofit treatment facilities were sized based upon the DCIA within each of the 18 hydrologic sub-basins and the type of treatment (i.e., retention or wet detention) which could be provided within each sub-basin based on available soils and groundwater information. Table 9-4 presents the conceptual cost estimate to provide retrofit treatment of the DCIA in Lake County. It should be noted that no treatment facilities were planned for areas in the Ocala National Forest except for the area contributary to the Shocklee Heights sink area. It is recommended that these conceptual retrofit facilities be better defined by performing detailed basin studies as part of the County's overall Stormwater Management Program. 9.2.3 ADDITIONAL STORMWATER PROGRAM NEEDS AS stated in the County's Comprehensive Plan, Lake County needs to perform a Stormwater Master Plan by 1993. This Master Plan is recommended to be performed on a basin-by-basin basis, that is, a basin study for each of the five major hydrologic basins. The basin studies would have sufficient field information to assure that the results of the studies can be implemented. Field information includes topograhical data for the basin LC1.9 TABLE 9-4 220-66-LAKE 05/09/91 CONCEPTUAL PROBABLE COSTS FOR RETROFIT TREATMENT FACILITIES and field surveying information for major structures. The basin studies are recommended to be of sufficient detail to allow the study to be submitted to the Water Management Districts for conceptual permitting approval. This would include water quantity evaluations and water quality analysis, with the recommended computer models, and comprehensive alternatives evaluations which are consistent with the County's goals, objectives, and policies. Table 9-5 presents the estimated costs to acquire the topographical and field surveying information, and to perform the basin studies for each basin. The total estimated cost to acquire the necessary data and perform the five basin studies is $5,032,000. 9.3 PRIORITIZATION Areas within the County can be prioritized to ensure that proper solutions for the problems are determined, that sound guidance is provided for newly developing areas, that environmentally sensitive areas are protected, and that public facilities are strategically placed. Priorities for the future Stormwater Management Basin Studies were established by an equal weighting of the following considerations: 1. Number and severity of water quantity problem areas in the basin; 2. Number and severity of water quality problem areas in the basin; 3. Predominance of recharge areas; 4. Predominance of wetland areas; and 5. Potential for high growth in the planning period. Table 9-6 lists the five basins in the County and their respective rank. The Oklawaha River basin ranked high in all aspects and is recommended to be studied first. The Withlacoochee River basin, especially the Lady Lake sub-basin, is the next critical basin for study due to high growth pressures. Table 9-7 provides a preliminary list of annual and capital costs per basin. The phasing of specific problem solutions were provided TABLE 9-5 LAKE COUNTY STORMWATER MASTER PLAN BASIN STUDIES COST ESTIMATE Estimated Probable Basin Cost* Oklawaha River $ 2,416,000 Wekiva River 728,000 St. Johns River 975,000 Withlacoochee River 805,000 Kissimmee River 208,000 TOTAL ESTIMATED COST $ 5,132,000 ------.------..----- * Cost includes topographical contour maps at 2-foot intervals for areas not currently covered in Lake County, field surveys for major open channel cross sections, and structure data (i.e., size, type, inverts, lengths, etc.), and engineering evaluations. TABLE 9-6 PRIORITIES FOR STORMWATER MASTER PLANNING BY BASIN Water Water Quantity Quality Recharge Wetlands Growth Overall Problem Problem Area Area Change Basin Rank Rank Rank Rank Rank Rank Oklawaha River 1 1 1 1 1 1 Wi thlacoochee 2 2 2 3 2 2 Wekiva River 3 4 3 2 3 3 St. Johns River 4 3 4 4 4 5 Kissimmee River 5 5 5 5 5 4 TABLE 9-7 STORMUATER MANAGEMENT PROGRAM PROBABLE COST SUMMARY I I Okl awaha Ulthl acoochee Uekiva St. Johns Kissimmee River Basin Rlver Basin River Basin River Basin River Basin TOTALS .($I ($1 ($1 ($1 ($1 ($1 ANNUAL MAINTENANCE 885.000 307.000 CAPITAL EXPENDITURES Problem Area Improvements Future Studles and Field and Aerlal Surveys Retrofit Improvements TOTAL CAPITAL EXPENDITURES in Table 9-3. It is recommended that public information workshops be conducted to finalize the priority phasing schedule of problem area improvements and future basin studies. 9.4 ADDITIONAL PROGRAM NEEDS As Lake County progresses with subsequent phases of its Stormwater Management Program, the County needs to evaluate its ability to fund and adminster the program. As shown in Table 9-7, approximately $1,800,000 per year will be required to provide adequate annual maintenance, and approximately $116,400,000 could be expended to implement identified capital improvements. To implement this program, efficient administration of the program and alternative funding sources will be required. Thus, it is recommended that the County conduct a stormwater administration and financing study to determine the most efficient methods to administer the program and pursue the creation of an alternative funding source such as a stormwater utility. APPENDIX A Lake County Stormwater Sub-~lement CHAPTER VI PUBLIC FACILITIES ELEMENT 9J-5.011 (2) F.A.C. Lake County, Florida Stormwater Sub-Element Chapter VI-C GOALS, OBJECTIVES, AND POLICIES. This section establishes the Stormwater Sub-Element Goals, Objectives, and Policies for implementation pursuant to Section 95-5.011 (2), Florida Administrative Code. GOAL 6C: STORMWATER. SURFACE WATER. AND GROUNDWATER MANAGEMENT. ULKE COUNTY SHALL PROVIDE SOUND STORMWATER, SURFACE WATER, AND GROUNDWATER RESOURCE MANAGEMENT TO PREVENT FLOOD DAMAGE AND PROTECT WATER QUALITY TO ENSURE THE SAFETY AND WELL BEING OF THE CITIZENS OF LAKE COUNTY. OBJECTIVE 6C-1: CORRECT EXISTING DEFICIENCIES. Lake County shall identify and correct existing facility deficiencies on a priority basis. The County shall address known problems such as flooding and degradation of surface and groundwater quality. Policy 6C-1.1: BlFminate Existina Deficiencies. By 1993, Lake County shall develop specific plans to correct existing stormwater problems in the following priority areas: 1. Wolf Branch Road -2. Shocklee Heights Sink 3. Astor Area 4. Lake Yale Dike based upon the Lake County Stormwater Management Needs Assessment completed in 1990. Policy 6C-1.U: Purchase Wolf Branch Sink. Lake County shall coordinate with the Oklawaha Basin Recreation and Water Conservation and Control Authority in Lake County for the purchase of the Wolf Branch Sink and surrounding land. Policy 6C-1.2: com~letionof Stormwater Manaaernent Master Plan. Lake County shall complete a Stomwater Management Master Plan by 1993. The County, in coordination with the appropriate Federal and State and Local agencies, shall seek additional opportunities for funding joint projects to facilitate the County-wide Stormwater Management Master Plan. Policy 6C-1.3: Stormwater Manaaement Ordinance. By 1991, Lake County shall finalize, adopt, and implement the Lake County Stormwater Management Ordinance to establish a sound permitting, construction certification, and enforcement program. The County VI-C-1 December 21, 1990 Lake County Stormwater Sub-Element shall continue to pursue delegation of responsibility from the regulatory agencies. Where necessary, the Ordinance shall be as. compatible as possible with the regulatory agencies' regulations. Policy 6C-1.4: Fundina for Stomwater Manaaement. By 1991, Lake County shall-initiate a stormwater utility or other permanent funding mechanism for funding stormwater improvements. These new funding sources shall be utilized to develop and implement the Stormwater Management Master Plan. Policy 6C-1.5% Contour Interval Ma~~inq.By 1993, a complete detailed County-wide mapping at one (1) foot contour intervals shall be obtained from the SJRWMD and the SWFWMD. The Federal Insurance Rate Map (FIRM) shall continue to be used as the basis for development review. Policy 6C-1.6% Priorities for Stormwater Master Planning. Lake County shall set the following basin priorities for detailed master planning: 1) Oklawaha River, 2) Withlacoochee River, 3) Wekiva River, 4) St. Johns River, 5) Kissimmee River. By 1994, Lake County shall develop corrective measures for minimizing or eliminating identified public threats through targeting the portion of the basin evaluated to be of greatest concern. Policy 6C-1.7: Five Year Schedule of Facilitv Improvements. Within five years after the completion of the Stormwater Management Master Plan, Lake County shall correct or minimize the corresponding set of deficiencies that are identified as priorities in terms of the public's health and safety. Beginning in 1992, Lake County's Environmental Services Department shall, as part of the annual update of the five year Capital Improvements Program, prepare a list of prioritized stormwater improvements. Lake County shall prioritize and correct the deficiencies identified in the Stormwater Management Master Plan through the Capital Improvements Program, with consideration given to the following criteria. A. The first priority should be given to those deficiencies that threaten health, safety and welfare. This policy shall be interpreted to include drainage wells identified in the Stormwater Management Master Plan that are known to be a public threat to the aquifer or public drinking well water supply. B. The second priority should be given to those improvements that are necessary to bring the existing substandard systems and subsystems up to the adopted LOS appropriate for each basin with respect to flooding or pollution abatement deficiencies, as reflected by the stated goal or improving current levels of service. C. The third priority should be given to those improvements that represent opportunities to participate on "joint projects" (with other public or private entities) that will result in the more efficient construction or replacement of improvements over time. VI-C-2 December 21, 1990 Lake County Stormwater Sub-Element Policy 6C-1.8: Coordination with Adjacent Jurisdictions. Lake County shall cooperate and consult with the 14 municipalities and adjoining counties, in the completion of the Stormwater Management Master Plan and the subsequent identified improvements. Lake County shall encourage the municipalities to enact stormwater management programs which are consistent with State, Regional, and County requirements for new development. OBJECTIVE 6C-2: GUIDE FUTURE DEVELOPMENT. Lake County shall manage and coordinate its stormwater review and implementation process to address the needs of future development. Policy 6C-2.1: Im~actAssessment Durina Develomnent Review. By 1992, Lake County shall require, as part of the development review process, an impact assessment that addresses the effects of new development on existing storinwater management systems. This review process shall consider how the stormwater management systems will operate at build-out. Policy 6C-2-22 8.By 1996, Lake County shall reevaluate the effectiveness of surface water management criteria for swales, open channels, and culverts for their applicability and effectiveness. Policy 6C-2.3: Review of Land Develo~mentReaulations. Lake County's Land Development Regulations shall incorporate Stormwater Management Design Standards as contained within the Lake County Stormwater Management Ordinance. These design standards shall include, at a minimum, the following criteria: A. In new developments, Lake County shall require a retentioddetention system that limits peak discharge of a developed site to the peak discharge from the site in an undeveloped condition for a specified design stonn. B. Stormwater collected in any development must be managed in a manner that will not cause personal or property damage to upstream and/or downstream property owners; C. Any segment of a stormwater system which is to be dedicated and made a part of the County's Stormwater System shall be designed to accommodate upstream flows through the system; D. Each phase of any development shall exist as an independent unit capable of having its surface water management needs met by the stormwater system design; and E. Wet detention areas shall be designed as limnic systems and measures shall be provided to protect the publics health, safety, and welfare. Where no fencing is present the space shall count as part of the open space requirements. VI-C-3 December 21, 1990 Lake County Stormwater Sub-Element Policy 6C-2.4: Storwater Convevance Riahts-of-Wav. Lake County shall pursue, if necessary, the acquisition of stormwater rights- of-way andlor easements necessary for the operation and maintenance of the County's stormwater system. Policy 6C-2..5: Desicm of Stormwater Manaaement Svstems. Lake County shall require that all stormwater management devices constructed be designed to County standards. Policy 6C-2.6: provide Stormwater Services. Lake County shall provide adequate stormwater services to maintain the adopted level of service standards based upon, but not limited to, the following considerations: A. The protection and maintenance.of the public's health, safety, and welfare; B. The protection and maintenance of the property; C. The protection of existing public investment; D. The protection of water quality; E. The reduction of operating and maintenance costs; and, F. The achievement and satisfaction of Regional, State and Federal regulations. Policy 6C-2.7: provide Effective Stormwater Treatment. Lake County shall require that plans for expansion, modifications, and replacement of existing development, excluding phased development, meet the adopted level of service, where such stormwater treatment is currently inadequate. Policy 6C-2.8: Cost Effective Stormwater Manaaement. Stormwater management systems shall employ the most cost-effective pollutant control techniques available that are consistent with sound environmental management and which provide the greatest efficiency in stormwater runoff pollutant removal. A continuing maintenance program shall be approved by the County. Policy 6C-2.9: Non-Structural Solutions to Stormwater Problems. Lake County shall require that non-structural improvements be utilized to solve existing and future stormwater problems where it is economically and/or physically possible to utilize these approaches. Where structural approaches must be utilized, the County shall ensure that environmental damage is minimized. Non- structural solutions may include the use of conservation areas and maintaining floodplain protection (capacity) through the provision of compensating storage. VI-C-4 December 21, 1990 Lake County Stormwater Sub-Element Policy 6C-2.10: Desim Storms Level of'service Standards. Lake County hereby adopts the following minimum twenty-four (24) hour level of service standards for design storms: Facility...... Type Design Storm Bridges 50 Year Principal Arterial Bridges 100 Year Canals, ditches, roadside swales, or culverts 25 Year for stormwater external to the development Canals, ditches, roadside swales, or culverts 10 Year for stormwater internal to the development Crossdrains 25 Year Storm sewers 10 Year Major DetentiodRetention structures1 For the Probable Maximum Precipitation as required by SJRWMD Minor DetentiodRetention structures1 25 Year First floor elevation must be 18" or above the 100 year Flood Elevation -0------.------..-----.------.-----...---.-.--m--..-----...-.-.- Major/Minor DetentiodRetention Structures are based on Hazard Classification for Dams and Impoundments as defined by the SJRWMD. -.-.----.----.----..------.-----..-.----.-.---...----.--.---m Policy 6C-2.11: Desiun Storm Level of Service Standard for Landlocked Areas. Landlocked areas shall maintain a twenty-five (25) year ninety-six (96) hour design storm level of service standard . Policy 6C-2.12: Stormwater Manaaement for Roadwav Construction. Lake County, in coordination with the Florida Department of Transportation, shall require appropriate or suitable stormwater management systems for the construction or reconstruction of all arterial and collector roadways within the County. Policy 6C-2.13: Consideration for Natural Hvdro~eriod. Lake County shall consider the natural hydroperiod of receiving waters when stormwater management systems are designed. Policy 6C-2.14: Accepted Stormwater Run-Off Computer Models. By February 1992, the Lake County Land Development Regulations shall include provisions for the acceptance of computer models which VI-C-5 December 21, 1990 Lake County Stormwater Sub-Element calculate stormwater run-off. These models shall be limited to those accepted by regulatory agencies. OBJECTIVE 6C-3: MAXIMIZE FACILITY USE AND DISCOURAGE INEFFICIENT LAND USE. Lake County shall maximize the use of existing stormwater management facilities and available capacity, and promote efficient land utilization through the implementation of appropriate technology. Policy 6C-3.1: Utilize New Technoloaies. Lake County shall utilize new technologies and operational procedures as they become feasible. Policy 6C-3.2: Innovative Stormwater Manaaement. The County shall actively participate in the development of innovative stormwater management programs which protect and conserve the County's water resources. Policy 6C-3.3: Alternative Stormwater Systems. Lake County shall continue to investigate alternative stormwater management systems for providing efficient stormwater management service. Policy 6C-3.4: Efficient Land Use Desiunations. Lake County shall designate land uses on its Future Land Use Map which incorporate stormwater management without promoting inefficient ' land utilization. Policy 6C-3.5: Stormwater Manaaement Performance Standards. By February 1992, the Lake County Land Development Regulations shall include the performance standards that are contained within the Lake County Stormwater Management Ordinance which require new developments to utilize stormwater management systems which are designed to maintain predevelopment levels of stormwater discharge for the design storm specified by the Lake County Pollution Control Board or other appropriate governmental agencies, and which consider stormwater management systems on adjacent development to promote efficient land use. Policy 6C-3.6: Adeuuate Flood Protection. Lake County Land Development Regulations shall include provisions that require stormwater management systems within all development to be designed and installed to provide adequate flood protection for all primary structures and to protect the structural integrity of all roadways. Policy 6C-3.7: Provide for Stormwater Run-Off. Lake County Land Development Regulations shall require that all new stormwater management systems provide for the safe handling of all stormwater run-off that flows into, across, and is discharged from the site without creating any additional flooding to adjacent property owners. VI-C-6 December 21, 1990 Lake County Stormwater Sub-Element Policy 6C-3.8: Desicrn Standards. Lake County shall utilize the design standards contained within the Lake County Stormwater Management Ordinance for construction and maintenance requirements of all stormwater retentioddetention systems and ensure compliance with these requirements to prevent degradation of the receiving surface water bodies. OBJECTIVE 6C-4t PROTECT THE FUNCTIONS OF NATURAL PEATURES: Lake County shall 1) minimize the occurrence of flooding that is a threat to human health or property; 2) identify and prohibit drainage wells 3) improve its ability to manage stormwater so as to minimize the degradation of surface water in order to protect the functions of natural features. Policy 6C-4-11 Protection of Natural Features throuah the Land Jkveloment Recrulations and the Stormwater Manaaement Ordinance. By 1992, Lake County shall ensure that the stormwater management regulations, contained in the Land Development Regulations, continue to protect natural features by approving only those developments that are consistent with the Lake County Stormwater Management Ordinance. Policy 6C-4.2: Flood Hazard Area Restrictions. Lake County shall not approve the construction of any proposed road, street, or facility within a designated flood hazard area, unless mitigation measures, as set forth within the Land Development Regulations, are installed by the developer to overcome an identified flood hazard. All mitigation measures installed by the developer must be certified acceptable by the County prior to development. The Lake County Stormwater Management Ordinance shall contain provisions for the use of compensating storage to compensate for the loss of floodwater storage capacity. Policy 6C-4.3: Best Manaaement Practices. Lake County shall require that Best Management Practices for agriculture, construction and silviculture be employed to protect the function of stormwater management and to minimize contributions of poor quality stormwater run-off to receiving water bodies. Policy 6C-4.4: Location of RetentiodDetention Areas. Lake County shall require that retentioddetention areas be designed and located so as to not adversely reduce the existing flood storage of the flood plain. Policy 6C-4.5: Diversion of the First-Flush of Stormwater. The Lake County Land Development Regulations shall include the provisions that are contained within the Lake County Stormwater Management Ordinance which require the diversion of the first flush of stormwater to separate detention or retention facilities for new or redesigned stormwater management systems which use isolated wetlands. Provisions shall also be included within the Land Development Regulations which address the use.of wet detention facilities where it can be demonstrated that such VI-C-7 December 21. 1990 Lake County Stormwater Sub-Element facilities provide for treatment of stormwater at the adopted level of service. Policy 6C-4.6: Drainaae and Injection Wells. Consistent with Policy 7-2.11 within the Conservation Element, Lake County shall prohibit the use of drainage and injection wells for the purposes of stormwater management. Existing drainage and injection wells situated within the County shall be filled and/or capped by the owner of the well and/or the County. These drainage and injection wells shall be phased out as soon as practical, in conformance with the Stormwater Management Master Plan. Policy 6C-4.7: Desianation of Outstandina Lake Countv Waters Proaram. In furtherance of policies within the Conservation Element, Lake County Land Development Regulations shall include provisions, by 1993, for the establishment of an Outstanding Lake County Waters Program which will identify those water bodies which possess exceptional water quality. The Lake County Stormwater Management Master Plan shall include measures to protect those lakes included in the Outstanding Lake County Waters Program. Through the establishment of the Outstanding Lake County Waters Program, lakes, for which stormwater is determined to be a major water quality problem, shall be identified and corrective measures shall be undertaken as part of the Stormwater Management Master Plan. VI-C-8 December 21, 1990 APPENDIX B APPENDIX B STORMWATER FACILITY INVENTORY BY SUB-BASIN FACILITY MAINTENANCE BAS IN SUB-BASIN DESCRIPTION ENTITY Okl awaha River Lake Weir ------Lake Yale F04005 SIX~'CBC County F01005 36" RCP County F01020 48" CMP City FOlOlO 54" CMPA County F01015 36" RCP City Lake Griffin GO1050 48" RCP FDOT GO1055 5'x5' CBC FDOT GO1060 48" RCP FDOT GO7005 4'x4' CBC FDOT GO7010 4'x4' CBC FDOT GO9005 2-48'' RCP County 601005 4'X6' CBC County GO5005 36" RCP FDOT 605010 42" RCP FDOT 60 50 15 42" RCP County 605020 48" RCP F0 0 T GO5025 36" RCP FDOT 605030 42" RCP FDOT Lake Eustis HI1005 36" RCP County H09005 36" CMP FDOT H04005 36" RCP City H04010 48" RCP City H04015 8'xS' CBC County H01005 36" RCP County HOlOlO 4'x2' CBC F0 0 T H01015 10ax3' CBC FDOT H01020 36" RCP County H01025 36" RCP County H05005 2-48" RCP County H05010 48" RCP County Golden Triangle I01005 36" CIP County I01010 36" CIP County I010 15 3'x3' CBC County I01020 36" CMP County I01025 36" CMP County I01030 36" CMP County I01035 36" CMP County I02005 36" CMP County I05005 36" CMP FDOT I05010 3-36" RCP F0 0 T ------,------APPENDIX B (continued) STORMWATER FACILITY INVENTORY BY SUB-BASI N FACILITY MAINTENANCE BAS IN SUB-BASIN ID DESCRIPTION ENTITY Okl awaha River Golden Triangle I04005 2-8'x8' CBC FOOT (Continued) (Continued I04010 36" CMP County I09005 48" RCP County I09010 7Ix3' CBC County I09015 3-36" RCP County I09020 48" RCP County Lake Apopka 501015 8'x4' CBC County 501020 36" CMPA County 507005 4Ix3' CBC FOOT 507010 8'x4' CBC FDOT 509005 7'x4' CBC County 512005 6'x3' CBC County 512010 5'x2' CBC County 501005 8Ix6' CBC County 501010 2-36" RCP County Lake Harris K24005 2-36" RCP County K17005 42" RCP County KO1010 42" CMP County KO1065 2-48" RCP County KO1070 36" RCP County KO1075 36" CIP County KO1080 36" RCP County KO1085 48" RCP County KO1090 36" RCP County KO1095 42" RCP FOOT KO1050 8Ix8' CBC FOOT KO4005 4'x4' CBC County KO40 10 46" RCP City KO1055 36" RCP City KO1060 36" CMP FOOT KO1005 36" CMP County KO9005 36" RCP County KO1020 48" CMP County K10005 6'x4' CBC County KlOOlO 6Ix4' CBC County K11005 36" CMP County KllOlO 1O1x4* CBC County K10015 48" CMP County K11020 36" CIP County K11025 6'x4' CBC FOOT K11030 4'x4' CBC FOOT K14005 36" CMP County K16005 2-48" CMP County K20005 48" CMP County _------o------...... ------APPENDIX B (continued) STORMWATER FACILITY INVENTORY BY SUB-BASIN FACILITY MAINTENANCE BASIN SUB-BASIN DESCRIPTION ENTITY Pal at1akaha 4-48" CMP County 2-36" RCP FOOT 5'x3' CBC FOOT 36" RCP County 60" CMP County 2-36" CMP County 4Ix4' CBC FOOT 3'x3' CBC County 2-6'x3' CBC County 9'x5' CBC County 9'x3' CBC County 24" RCP County 2-6Ix4' CBC County 36" DIP County 3-60'' CMP County 2-48" RCP County 2-48" RCP County 48" CMP County 48" CMP LCWA 48" CMP LCWA 48" CMP LCWA 48" CMP LCWA Wekiva River 81 ackwater Creek 2-36" RCP County 36" RCP County 36" RCP County 48" RCP County 45" RCP County 48" RCP County 48" RCP County 36" RCP County 48" RCP County 2-42" RCP County 36" RCP County 2-36" RCP County 36" RCP County 36" CMP County 36" RCP County 48" CMP County Wekiva River ------...... APPENDIX B (continued 1 STORMWATER FACILITY INVENTORY BY SUB-BASIN FACILITY MAINTENANCE BASIN SUB-BASIN DESCRIPTION ENTITY St. Johns River A1 exand er Springs A10005 2-48'' CMP County A04005 42" RCP County A08005 42" RCP County A08010 36" RCP County A12005 2-36" RCP County A1 20 10 42" RCP County A12015 48" CMP County A12020 36" RCP County AlOOlO 48" CMP FDOT A10015 48" CMP FDOT A15005 2-42" CMP County A01005 36" RCP County With1 acoochee Lady Lake --- River Loggy Pond Swamp NO3005 36" CMP I County NO7005 2-60" CMP County N10005 42" CMPA , County NlOOlO 36" CMP County N11005 7-60" CMP County NllOlO 36'' CMP County N12005 3-48'' CMP 1 County N12010 4-48" CMP County N13005 48" CMP County N15005 2-3O8'x48" ECP County N17005 36" CIP County NO6005 36" DIP I County NO6010 36" RCP / County SE Fruitland Park - - - Grovel and-Mascotte P10005 3-48'' RCP County PO9005 36" RCP County 012005 2-36" CMP County PO7005 36" CMP County PO8005 3-48" CMP 1 County PlOOlO 48" RCP , County P10015 2-60'' RCP County P12010 2-54" RCP FOOT P12015 2-48'' RCP County PI3005 2-48" CMPA County P13010 4-48" RCP FOOT P14005 48" RCP ------I FOOT APPENDIX B (continued) STORMWATER FACILITY INVENTORY BY SUB-BASIN - FACILITY MAINTENANCE BAS IN SUB-BASIN ID OESCRIPTION ENTITY With1 acoochee Lake Okahumpka 903005 118x7.5' CMPA County River 903010 60" RCP County (Continued 1 903015 42" RCP County 903020 g8X3* CBC County 901005 2-36" RCP FDOT Reed Hammock Pond ------ Kissimmee River Trout Lake ------I I I APPENDIX B LAND USE BY SUB-BASIN LAND USE PERCENTAGES BY CDM TYPE BASIN SUB-BASIN ------1 2 3 4 5 6 7 8 9 10 Oklawaha River Lake Weir 17351511 5 4 3 0 3 7 Lake Yale 1536 3 5 3 1201324 Lake Griffin 1229 6 4 4 2 3 01526 Lake Eustis 923 5 4 8 1401036 Golden Triangle 722 7 410 150 736 Lake Apopka 1049 8 3 2 0 3 0 916 Lake Harris 735 5 3 4 1301626 Palatlakaha 643 8 2 102 02414 Wekiva River Blackwater Creek 23 30 11 5 3 0 1 0 19 7 Wekiva River 13392110 4 0 109 3 St. Johns River AlexanderSprings 48 8 4 1 1 1 1 0 26 9 Withlacoochee River ~adyLake 17351511 6 4 4 0 2 6 Loggy pond Swamp 42219 0 0 0 0 054 1 SEFruitlandPark 11 26 7 6 9 2 8 0 21 10 Groveland-Mascotte 10 42 9 2 1 0 1 0 27 7 Lake Okahumpka 10 24 6 5 10 2 8 0 25 10 ReedHammockPond 8 41 8 2 1 0 2 0 31 6 Kissimmee River Trout Lake 552 5 0 0 0 102116 APPENDIX B SOILS BY SUB-BASIN SUB-BASIN 8 BY SOIL TYPE BASIN SUB-BASIN AREA (AC ----A BCD Oklawaha Lake Weir Lake Yale Lake Griffin Lake Eustis Golden Triangle Lake Apopka Lake Harris Palatlakaha Wekiva Blackwater Creek Wekiva River St. Johns River Alexander Springs Withlacoochee Lady Lake Loggy Pond Swamp SE Fruitland Park Groveland-Mascotte Lake Okahumpka Reed Hammock Pond Kissimmee Trout Lake APPENDIX C (Provided to Lake County under separate cover)