Treatment of Urban Stormwater Runoff by Sedimentation
Total Page:16
File Type:pdf, Size:1020Kb
TREATMENT OF URBAN STORMWATER RUNOFF BY SEDIMENTATION by Kathy Lee Ellis Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Environmental Science and Engineering APPROVED: 1'J. R~nd'a1·1 . Chairman T. J. ~; zZird R. C. Hoehn W. R. Knocke July, 1982 Blacksburg, Virginia ACKNOWLEDGEMENTS The author would like to express her deep gratitude to Dr. Clifford Randall, Dr. Thomas Grizzard, Dr. William Knocke, and Dr. Robert Hoehn for their guidance and assistance in the developrrent, implerrentation, and writing of this project, and for serving as committee members. The author wishes to thank the entire staff at the Occoquan Watershed Monitoring Laboratory for their assistance as well as tolerance throughout the project, Special thanks goes to Kathy Saunders for her help with the computer. Janes Hopper deserves special thanks for the many dreary hours he spent with the author waiting for rain. ii TABLE OF CONTENTS PAGE ACKNOWLEDGEMENTS. ii LIST OF FIGURES........................................... v LIST OF TABLES............................................ viii I . INTRODUCTION. 1 II. LITERATURE REVIEW......................................... 3 The Urban Stonnwater Problem............................ 3 Stonnwater Management................................... 8 Storage Basins.......................................... 9 Sediment-Pollutant Relationships........................ 11 Sedimentation Theory.................................... 13 Sedimentation Efficiency................................ 17 Surrvna ry . 25 III. METHODS ANO MATERIALS..................................... 25 Sampling Site Description............................... 26 Sample Collection....................................... 28 Sample Ana 1ys is . 29 Data Analysis........................................... 33 IV. RESULTS. 35 Sol i ds . 35 Particle Size Distribution ........................ ~..... 54 Nutrients. 55 Heavy Meta 1s............. 64 Organic Matter.......................................... 70 Total and Fecal Coliform Bacteria....................... 72 Dissolved Oxygen........................................ 73 iii TABLE OF CONTENTS (cont.) PAGE Variations Between Columns.............................. 75 V. DISCUSSION................................................ 79 The Efficiency of Stormwater Settlement................. 79 The Use of Settling Data in Basin Design................ 104 VI. CONCLUSIONS............................................... 113 VIII. REFERENCES................................................ 115 APPENDIX.................................................. 120 VITA ................... I.................................. 145 ABSTRACT iv LIST OF FIGURES FIGURE PAGE 1 Ideal Sedimentation Basin ........................... 14 2 Laboratory Settling Column .......................... 19 3. Sedimentation Removal of TSS from Fair Oaks Mall Stormwater - July 4, 1981 Samp 1e .............................................. 36 4 Sedimentation Removal of TSS from Manassas Ma 11 Stormwa ter - July 5, 1981 Sample .............................................. 37 5 Sedimentation Removal of TSS from Fair Oaks Mall Stormwater - June 20, 1981 Sample ............................................... 38 6 Sedimentation Removal of TSS from Fair Oaks Mall Stormwater - October 23, 1981 Sample ............................................... 39 7 Sedimentation Removal of TSS from Manassas Mall Storrrwater - July 26, 1981 Sample............................................... 40 8 Sedimentation Removal of TSS from Manassas Mall Stormwater - August 11, 1981 Samp l e . 41 9 Sedimentation Removal of TSS from Manassas Shopping Center Stormwater - September 15, 1981 Sample............................................... 42 10 Changes in Suspended Solids Concentrations with Settling Time for the Fair Oaks Mall Sample of July 4, 1981 ..... ·................................... 44 11 Changes in Suspended Solids Concentrations with Settling Time for the Manassas Mall Sample of July 5, 1981......................................... 45 12 Changes in Suspended Solids Concentrations with Settling Time for the Fair Oaks Mall Sample of June 20, 1981 ....................................... 46 13 Changes in Suspended Solids Concentration with Settling Time for the Fair Oaks Mall Sample of October 23, 1981 .................................... 47 v LIST OF FIGURES (cont.) FIGURE PAGE 14 Changes in Suspended Solids Concentrations with Settling Time for the Manassas Mall Sample of July 26, 1981 ....................................... 48 15 Changes in Suspended Solids Concentrations with Settling Time for the Manassas Mall Sample of August 11, 1981 ..................................... 49 16 Changes in Suspended Solids Concentrations with Settling Time for the Manassas Shopping Center of September 15, 1981 ............................... 50 17 The Effect of Initial TSS Concentrations on Removal Rates ....................................... 52 18 Percent Reduction of TSS with Settling Time in Samples with Low Initial Concentrations of 15, 35, and 38 mg/L (July 4, July 5, and June 20) ........... 87 19 Percent Reduction of TSS with Settling Time in Samples with Initial TSS Concentrations of 100, 155, and 215 mg/L (October 23, July 26, and August 11) .... 88 20 Percent Reduction of TSS with Settling Time in Sample with an Initial TSS Concentration of 721 mg/l (September 15) ...................................... 89 21 Percent Reduction of TSS with Settling Time in Cambi ned Results .................................... 90 22 Percent.Reduction of Suspended Phosohorus with Settling Time in Samples with Initial TSS Con- centrations of 15, 35, and 38 mg/1 (July 4, July 5, and June 20) ........................................ 91 23 Percent Reduction of Suspended Phosphorus with Settling Time in Samples with Initial TSS Con- centrations of 100, 155, and 215 mg/l (October 23, July 26, and August 11) ............................. 92 24 Percent Reduction of Suspended Phosphorus with Settling Time in the Sample with an Initial Con- centration of 721 mg/l (September 15) ............... 93 25 Percent Reduction of Suspended Phosphorus in Combined Results .................................... 94 vi LIST OF FIGURES {cont.) FIGURE PAGE 26 Percent Reduction of Suspended Lead with Settling Time in Samples with Initial TSS Concentrations of 100, 155, and 215 mg/L (Octoner 23, July 26, and August 11) ......•....•...... 95 27 Percent Reduction of Suspended Lead with Settling Time ~in the Samples with Initial TSS Concentration of 721 mg/L (September 15) .......... 96 28 Percent Reduction of Suspended Lead with Settling Time in Combined Results ..................... 97 29 Percent Reduction of Total Kjeldahl Nitrogen with Time in Samples with Initial TSS Concen- trations of 15, 35, and 38 mg/L (July 4, July 5, and June 20) .................................. 98 30 Percent Reduction of Total Kjeldahl Nitrogen with Settling Time in Samples with Initial TSS Concentrations of 100, 155, and 218 mg/L (October 23, July 26, and August 11) ...•.............. 99 31 Percent Reduction of Total Kjeldahl Nitrogen with Settling Time in the Sample with an Initial TSS Concentration of 721 mg/L (September 15) .......... 100 32 Percent Reduction of Total Kjeldahl Nitrogen with Settling Time in Combined Results •............... 101 33 Various Specific Gravity Values and the Corresponding Overflow Rate ......................................... 112 Vii LIST OF TABLES TABLE PAGE I Comparison of General Water Qualities (8) ........... 4 II Nutrients Grouped According to Absorption Partition Coefficients (30) ...........•............. 12 III Conversion of Settling Velocities to Over- f 1ow Rates . 17 IV Average Sedminentation Removed Values from Combined Sewer Overflow as Cited by the EPA (42) from the City of New York Environmental Portection Administration (43) ...................... 20 v Sampling Site and Dates of Collection ............... 27 VI Sample Volumes and Time Taken ....................... 30 VII Instrument Detection Limits for Heavy Metal Analysis....................................... 32 VIII Parameters Derived from the Manipulation of Laboratory Data .................................. 34 IX Changes in Percent Volatile Suspended Solids during Sedimentation ................................ 53 x Percent Reduction for Nutrient Concentrations ....... 56 XI Changes in the Percentage of Soluble and Suspended Phosphorus after 48 Hours of Settlement .......................................... 63 XII Percent Reductions for Lead and Zinc Concentrati ans ...................................... 66 XII I Dissolved Oxygen Concentration Changes with Time and Depth ................................. 74 XIV Statistics Derived from Data for Column Comparison........................................... 75 xv Percent Reduction Values Averaged Together from the Seven Stormwater Samples Analyzed .......... 83 XVI Comparison of Percent Reduction Values from the Current Project with those from the Literature ...... 85 viii LIST OF TABLES (cont.) TABLE PAGE XVII Total Initial Surface Area of Suspneded Particles and the Percent of the Total in each Size Range. 105 XVIII Relationship Between the Percent Reduction of Total Surface Area and Hater Quality Parameters ..... 108 XIX Relationship Between Reductions in Pollutant Concentration and Surface Area Reductions in Particle-Size Ranges of Suspended Solids ........... 109 ix I . INTRODUCTION