Piedmont Nc Wet Retention Basins

UNC-WRRI -97- 309 PIEDMONT N.C. WET RETENTION BASINS: PERFORMANCE FACTORS, SEDIMENTATION DYNAMICS, AND SEEPAGE LOSSES by Craig Allan, Randall Forsythe and John Diemer Department of Geography and Earth Sciences University of North Carolina at Charlotte Charlotte, NC 28223 The research on which the report is based was financed in part by the United States Department of the Interior, Geological Survey, through the N.C. Water Resources Research Institute. Contents of the publication do not necessarily reflect the views and policies of the United States Department of the Interior, nor does mention of trade names or commercial products constitute their endorsement by the Unites States Government. WRRI Project No. 70134 USGS Project No. 23 (FY '93 & '94) Agreement No. 14-08-000l-G2034 July 1997 One hundred fifty copies of this report were printed at a cost of $2,088.00 or $13.92 per copy. ACKNOWLEDGMENTS The field and laboratory components of this study were completed with assistance from Carla Asander, Ron Blackwelder, Kristen Blake, David Bristol, Charles Brockrnan, Robert Cox Jr., Debra Hannah, Matt Hansen, Courtney King, Dean London, Brad Newton, Doug Rupple, Anja Schulz, and the 1994 and 1995 ESCI Geoenvironmental Site Characterization classes at UNC Charlotte. Land owners who kindly granted us access to the ponds on their property included Charlotte-Douglas International Airport Authority, Charlotte-Mecklenburg Department of Parks and Recreation, W. Crowder, Davis Lake Homeowners Association, Z. Edwards, IBM, Northside Baptist Church, E. Passaly, Pawtuckett Golf and Country Club, Waverly Lake Swimming and Tennis Club and M. Webber. Chemical analyses were in part performed by the Mecklenburg County Environmental Protection Analytical Facility, Charlotte, North Carolina. Funding for the project was provided by the North Carolina Water Resources Research Institute and the Department of Geography and Earth Sciences, UNC Charlotte. Technical assistance was provided by James Matthews and Ed Menhinick, UNC Charlotte Department of Biology; Jeny Cook, North Carolina Department of Environmental Health and Natural Resources; and Drs. David Moreau and Robert Holman, North Carolina Water Resources Research Institute. The authors appreciate the efforts of four anonymous reviewers whose comments greatly improved an earlier version of this manuscript. ABSTRACT In this study an examination of environmental factors potentially affecting the ability of small ponds to perform as water quality improvement facilities has been undertaken within a 240 square mile (622 square km) region of the North Carolina Piedmont, largely within the urban - suburban region of Charlotte, N.C. The study has involved 10 sequential sets of analyses. The first was a remote sensing and GIs-based analysis of the relationships between watershed attributes and turbidity within ponds during interstorm or dry periods. The second and third were analyses of bulk sedimentation (in 20 basins) and sedimentary facies (in five ponds). The fourth was a study of the physical and chemical limnology of a suite of 20 ponds. The fifth and sixth were investigations of P, N and Zn chemistry of pond sediment. The seventh through tenth involved a multicomponent analysis of pond performance during a full year climatic cycle with additional detailed analyses of a number of storm events. The benefits of small ponds to serve as water quality improvement facilities is likely limited (without dredging) to - 50 years. Approximately 1% of the existing ponds are likely to need remediation or improvement each year, if the current estimate of a net 12% benefit to TSS removal by the ponds is maintained. The efficacy of ponds for pollutant removal is species-dependent. From 20% to 98% of TSS, BOD, COD, total P and some metals such as Pb and Cr are likely to be removed. Ponds have limited efficacy (40%) in removing other components such as C1, TKN and ortho P. Stratification in ponds during summer months produces anoxic, hypolimnionic waters which can dynamically exchange adsorbed constituents within sediment reservoirs with storm pulses of more dilute epilimnionic water. This can result in short periods of downstream TDS levels higher than under nonimpounded conditions. TABLE OF CONTENTS Page Acknowledgment iii Abstract v List of Figures X .. List of Tables xll1 Summary and Conclusions xv Recommendations ixx I. INTRODUCTION I. 1. Need for Research I. 2. Physical Models for Pond Design and Performance I. 2.1. Role of Sediment Loads I.2.2. Sediment Characteristics I. 2.3. Post-Depositional Chemical and Biological Effects I. 2.4. Sedimentation Dynamics in Ponds 11. PURPOSE AND OBJECTIVES 111. PHASE I. EVALUATION OF ENVIRONMENTAL FACTORS IN POND PERFORMANCE AND THE FATES OF ADSORBED/DESORBED CONSTITUENTS IN SEDIMENT 111.1. Regional Remote Sensing and GIs Analysis of Ponds 111.1.1 Methodology 111.1.1.a. Sizing Ponds 111.1.1 .b. Soil Erodability Factors and Slope Characteristics 111.1.1.c. Land Use Data 111.1.1.d. Ages of Ponds 111.1.1. e . Turbidity Indices 111.1.2. Results of Remote Sensing and GIs Analysis of Ponds 111.1.2 .a. Data Characteristics III.1.2.b. Turbidities versus Basin Characteristics vii 111.2. Field Study of 20 Ponds 111.2.1. Methods of Analysis for the 20 Ponds 111.2.1 .a. Selection Criteria 111.2.1 .b . Profiling and Coring 111.2.1. c . Core Description 111.2.1 .d. Smear Slide Preparation 111.2.1. e . Grain Size Analysis 111.2.1 .f. Water and Organic Analysis 111.2.2. Results 111.3. Depositional Facies Analysis of 5 Ponds 111.3.1 Methodology III.3.1.a. Profiling 111.3.1 .b. Logs and Cross Sections 111.3.2. Results III.3.2.a. Facies 111.3.2. b . Histories of Sedimentation in the Ponds 111.3.2 .c. Summary of Depositional Processes in Ponds II1.4. Field Collection of Pond Limnological Data 111.4.1 . Methodology 111.4.2. Results ' 111.5. Sediment Chemical Analyses 111.5.1 . Methodology 111.5.2. Results 111.6. Sediment Adsorption - Desorption Analyses 111.6.1. Theory 111.6.1 .a. Dilution Analysis 111.6.1.b. Adsorption Analysis 111.6.2. Methods 111.6.3. Results 111.6.3.a. Ammonium 111.6.3.b. Phosphorus 111.6.3 .c. Zinc IV. PHASE II. INVESTIGATION OF POND SEDIMENTATION AND SEEPAGE LOSSES FOR PARK ROAD PARK POND IV. 1. Determination of Sedimentology and Sedimentation Rates IV. 1.1. Methodology IV. 1.2. Results IV.2. Park Road Park Pond Monitoring and Annual TSS, TDS and Water Budgets IV .2.1. Methodology IV.2.1. a. Water Budget Analysis IV.2.1 .b. TSS and TDS Budget Analysis IV.2.2. Results IV.3. Settleability of Urban Runoff Pollutants IV. 3.1 Methodology IV.3.2 Results IV.4. Analysis of Pond Exchange with Ground Waters IV.4.1. Methods for Exchange Analysis IV .4.l. a. Direct Seepage Measurements IV.4.1. b. Indirect Estimates of Exchange Potential IV.4.2 Results IV.4.2.a. Results of the Seepage Analysis IV.4.2. b. Observations of Hydraulic Head IV .4.2. c . Calculations of Hydraulic Conductivity IV.4.2. d. Calculation of Potential Exchange with Ground Waters V. LITERATURE CITED Appendix 1. Tables of watershed parameters for the 250 pond regional study and the physical and sediment characteristics for each of the 20 ponds surveyed in the field. Appendix 2. Bathymetric and isopach maps for 20 pond survey. Appendix 3. Table of water and organic contents from 20 pond survey. Appendix 4. Core logs for 20 pond survey. Appendix 5. Locations and logs for cores from the 5 pond survey. Appendix 6. Chemical data: water, sediment, and adsorption/desorption results. Appendix 7. Core logs and cross-sections for Park Road Park Pond. LIST OF FIGURES Location map of study area with the history of pond construction in the Derita 7.5 rnin. quadrangle. Estimates of sediment loads in N.C. Piedmont surface waters. Concentrations of metals in sediments of variable sizes. Concentrations of metals in sediments with increasing depth of burial. Meteorological conditions prior to 1983 and 1990 image acquisition. 1983 versus 1990 turbidity indices for each pond. Correlation of 1983 and 1990 turbidity indices. Frequency plot of the SAIDA ratios for ponds in this study. Areas were derived from USGS 1:24,000 scale topographic maps. Graph of turbidity indices for 1983 and 1990 as a function of the SAIDA ratio for each basin. Graph showing the absence of a significant correlation of turbidities seen in the interstorm 1983 data set with a landcover-controlled variation in sediment loads. Graph of % acreage in the drainage basin area for a given pond that is formed of lands with slopes less than 8%. Basins with an abundance of low sloping land surfaces might be expected to have low sediment erosion rates and thus low turbidities. Graphs show the relationships between maximum age of ponds and calculated turbidity indices. (a) Pontoon boat for profiling and coring. (b) Correlation of radar two way travel times with depths to the sediment/paleosoil horizon. Lithologic cross-section of Hospital Pond, transect 1. Lithologic cross-section of Hospital Pond, transect 2. Lithologic cross-section of Hospital Pond, transect 3. Lithologic cross-section of Statesville B pond. Lithologic cross-section of Airport #2 pond, transect 4. Lithologic cross-section of Waverly Lake. Lithologic cross-section of Webber Farm pond, transect 5. Detention pond water quality parameters. Bottom sediment chemical concentrations. Schematic diagram of sediment-water interactions. Ammonium adsorption isotherms. Phosphorus adsorption isotherms. Zinc adsorption isotherms. Ammonium dilution analyses. Phosphorus dilution analyses. Zinc dilution analyses. Park Road Park Pond (a) instrument sites, (b) bathymetry, and (c) isopach maps. Park Road Park Pond transect A-A' Park Road Park Pond transect B-B' Park Road Park Pond transect C-C' Park Road Park Pond transect D-D' Cumulative sediment deposition rates.

Load more