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Weber and Wilson (1976) monitored the TSS concentrations in grab samples of runoff taken above and below several dams constructed of various materials, placed in waterways draining a highway construction site in Pennsylvania. Sediment loads trapped upstream of dams were estimated volumetrically and the contents were graded. Rock dams were observed to trap the bedload but that data was too variable to determine any reductions in TSS concentrations in the runoff. Reed (1978) reported approximately 5% reductions for both turbidity and suspended sediment load based on grab samples taken above and below rock berms on highway construction sites in Pennsylvania. Filtering efficiencies of approximately 30% for 5-cm rock berm and 90% for pea gravel at a 10% slope were reported by Kouwen (1990) using a monodispersed sediment. Filtration efficiencies increased for the 5-cm rock berm as the slope decreased. Flow rates of 2.3 L/s and 5.1 L/s were reported respectively for pea gravel and 5-cm rock at a head of approximately 150 mm. 2.6 Summary Temporary sediment controls remove solids by both sedimentation and filtration. The efficiency of these controls is affected by the particle size distribution of the construction runoff, characteristics of the control material, and the level of maintenance. Silt fences are one of the most commonly employed temporary controls. The fences are supported geotextile fabrics which are commonly characterized by their permitivity and apparent opening size, even though these parameters may not be appropriate for estimating sediment removal or hydraulic performance in the field. Previous research on the sediment reduction of silt fences has shown high removal in laboratory settings. However, in many of the studies, the solids used to create a sediment slurry had much larger diameters than the particles generally encountered in storm water runoff. Sediment removal effectiveness in the field have not been well documented. Even where high solids removal has been reported, the silt fences were not effective in reducing turbidity. 16
Much less research has been directed at characterizing the performance of rock berms. They appear to be much less effective than silt fences in reducing suspended solids loads. 17
Page 1: CRWR Online Report 95-6 AN EVALUATI
Page 5: ACKNOWLEDGMENTS This research was s
Page 8 and 9: 4.2.3 TSS Reduction Efficiency of S
Page 11 and 12: LIST OF TABLES Table Title Page 2.1
Page 13 and 14: and reduce construction duration (G
Page 15 and 16: 2. LITERATURE REVIEW 2.1 Introducti
Page 17 and 18: are characterized by lower permeabi
Page 19 and 20: size and is the estimated largest p
Page 21 and 22: corrected to a viscosity at 20 o C
Page 23 and 24: Influent samples from each of the t
Page 25: emaining 10% ranged from 15 to 50
Page 29 and 30: Figure 3.1 Location of Inventoried
Page 31 and 32: Table 3.2 Costs of Temporary Contro
Page 33 and 34: The inventory data indicate that si
Page 35 and 36: nature of construction activities r
Page 37 and 38: the discharge was 1542 mg/L, with a
Page 39 and 40: emained in suspension and were able
Page 41 and 42: Effluent Sampling Location Rock Ber
Page 43 and 44: 5. LABORATORY TESTS OF SILT FENCES
Page 45 and 46: along with runoff from the flume. T
Page 47 and 48: Table 5.3 Grain sizes, Gradation, R
Page 49 and 50: phenomenon is similar to sediment-l
Page 51 and 52: w A S h 1 Silt Fence Figure 5.4 Vol
Page 53 and 54: Many of the tests ended after 48 ho
Page 55 and 56: observation demonstrates that field
Page 57 and 58: The permeameter initially was set u
Page 59 and 60: Flow per Area, cm/s 40 30 20 10 0 y
Page 61 and 62: 6. CONCLUSIONS AND RECOMMENDATIONS
Page 63 and 64: topping. Knowledge of the performan
Page 65 and 66: Das, B. M., 1985, “Principles of
Page 67: Soil Conservation Service (SCS), 19
Page 71 and 72: Sample Descriptions Samples T1-T30
Page 73 and 74: Samples T109-T122 Although samples
Page 75 and 76: individual analyses of samples T1-T
Page 77 and 78:
2 6 7 4 1 Fort McGrude Bannister Ln
Page 79 and 80:
N T6 W W W W W W W W W W W T7 T5 T8
Page 81 and 82:
LEGEND: -W- -NW- T18 Water Boundary
Page 83 and 84:
T34 T38 NW NW NW NW T39 NW NW NW NW
Page 85 and 86:
T49 T50 T53 T54 T58 W T55 W W W W T
Page 87 and 88:
T75 W W W LEGEND: -W- -NW- T18 Wate
Page 89 and 90:
N T105 T106 T107 T108 T97 T98 T101
Page 91 and 92:
T117 N LEGEND: T118 -W- -NW- T18 Wa
Page 93:
APPENDIX B - RESULTS OF SAMPLE ANAL
Page 96 and 97:
SAMPLE DATE TIME DESCRIPTOR SITE TS
Page 98 and 99:
T64 4/7/93 10:55AM UPSTREAM C 6 NIA
Page 100 and 101:
Table B2. Results of Particle Size
Page 102 and 103:
Table B4. Silt Fence Turbidity Redu
Page 105 and 106:
Total Suspended Solids The analysis
Page 107 and 108:
APPENDIX D - CATALOG OF FLUME TESTS
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Test number: 1 Influent Samples : D
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Test number: 11 Influent Samples :
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
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Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
132
Page 141 and 142:
Amoco woven d = #20 sieve d = 8.50E
Page 143 and 144:
70 60 Flow per Area, cm/s 50 40 30
Page 145 and 146:
APPENDIX F - BASE EFFICIENCY TEST 1
Page 147 and 148:
Date = 9/17/94 Influent Samples: St
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