@article{babcock_mclaughlin_2013, title={Erosion control effectiveness of straw, hydromulch, and polyacrylamide in a rainfall simulator}, volume={68}, DOI={10.2489/jswc.68.3.221}, abstractNote={Temporary ground covers are used on construction sites to help establish vegetation and reduce erosion on disturbed areas. This study was an evaluation of straw, with or without polyacrylamide (PAM), and wood fiber hydromulch, with or without PAM, for reducing erosion and improving runoff water quality. Soil was packed to a depth of 0.06 m (0.2 ft) into 1 by 2 m (3.3 by 6.6 ft) boxes, which were placed under a rainfall simulator at a slope of 18°. Straw was applied by hand to boxes at a single rate of 2,240 kg ha−1 (2,000 lb ac−1) with no PAM (control), with dry granular PAM at either 37 or 74 kg ha−1 (33 or 66 lb ac−1), or with dissolved PAM at 37 kg ha−1. A wood fiber hydromulch was applied using a commercial hydroseeder at either 1,970 or 2,940 kg ha−1 (1,760 or 2,620 lb ac−1) with or without 37 kg PAM ha−1 (33 lb ac−1) mixed in the tank with the mulch. The rainfall simulator was run for 40 minutes at a rate of 37 mm h−1 (1.5 in hr−1) followed the next day by 8 minutes at the same intensity, for a total of 29.6 mm (1.2 in) of rainfall. The runoff water was collected and analyzed for turbidity and total suspended solids (TSS), and the time to runoff initiation was recorded. Turbidity was highest for the straw alone treatment at 1,500 and 1,040 nephelometric turbidity units (NTU) for first and second events, respectively. The lowest turbidity was in the hydromulch plus PAM treatments, ranging from 62 to 151 NTU. Adding the granular PAM at 37 kg ha−1 (33 lb ac−1) to straw reduced turbidity but increased sediment loss, while the dissolved PAM and the higher rate of dry PAM did not have the latter effect. This was apparently due to the slow dissolution of the dry PAM for the first several minutes of the intense rainfall. Applying PAM with straw provided benefits in reducing turbidity, but the dry application could exacerbate erosion if heavy rain occurs soon after application. The best results were usually obtained with hydromulch plus PAM, but adding PAM to a less expensive straw ground cover produced similar or better results than the hydromulch application without PAM.}, number={3}, journal={Journal of Soil & Water Conservation}, author={Babcock, D. L. and McLaughlin, R. A.}, year={2013}, pages={221–227} }
 @article{babcock_mclaughlin_2011, title={Runoff water quality and vegetative establishment for groundcovers on steep slopes}, volume={66}, ISSN={["1941-3300"]}, DOI={10.2489/jswc.66.2.132}, abstractNote={Construction sites can be a major source of sediment, a common pollutant in surface waters, because steep slopes are often bare during active construction. The use of mulch and polymers has been found to reduce erosion rates and improve runoff water quality on construction sites. Different erosion control methods on steep slopes (2:1) consisting of straw, straw plus 37 kg ha−1 (33 lb ac−1) linear anionic polyacrylamide (straw + PAM), and excelsior blankets were evaluated based on runoff water quality, vegetative establishment, or both at six construction sites. Plots (3 to 9 m [10 to 30 ft] wide by 9 m [29.5 ft] long) were established on cut slopes. Runoff was collected at four of six sites by installing plastic barriers to direct a portion of runoff into containers, later analyzed for turbidity and total suspended solids (TSS) in the laboratory. Large differences in water quality were often not statistically significant for individual storms due to high variability. However, when data were averaged across all storm events, the straw + PAM treatment reduced mean runoff turbidity at three of four sites and mean TSS at two of the four sites compared to straw alone. Maximum reductions in turbidity and TSS were 81% and 56%, respectively. Runoff from the excelsior plots had significantly lower turbidity and TSS than straw plots in one of three sites. Compared to straw + PAM, excelsior had significantly higher turbidity at two of three sites and higher TSS at one of three sites. All differences among treatments for individual storm events occurred within the first three events. Vegetative cover was determined in the field, and aboveground vegetation was harvested to determine biomass production. Neither vegetative cover nor biomass were affected by treatment, and average cover was 60% or less for five of the six sites. Rainfall patterns were largely responsible for vegetative growth, with heavier rainfall soon after seeding tending to reduce cover.}, number={2}, journal={JOURNAL OF SOIL AND WATER CONSERVATION}, author={Babcock, D. L. and McLaughlin, R. A.}, year={2011}, pages={132–141} }
 @article{bhardwaj_mclaughlin_babcock_2008, title={Energy dissipation and chemical treatment to improve stilling basin performance}, volume={51}, DOI={10.13031/2013.25321}, abstractNote={Surface water pumped from construction sites frequently contains high levels of turbidity and suspended sediment, which are not effectively removed using gravity-based systems. This study assessed the effects of modifying a permanent pool stilling basin with energy dissipaters and with the addition of polyacrylamide (PAM) on turbidity and suspended sediments. Turbidity was generated by injecting soil into flowing water at a fixed rate for 30 min in a source basin. Turbid water from this basin was pumped from the surface to the stilling basin with physical and chemical treatments. Three energy dissipater treatments were tested: bottom inlet level spreader (BILS; silt fence fabric installed with 40 mm opening from the basin bottom), coir baffles (900 g m-2 coir fabric with 0.45 open space fraction (OSF), and Pyramat baffles (synthetic fabric with 0.10 OSF). The tests were run either with or without PAM dosing by passing the flow over a solid PAM block at the stilling basin inlet. The physical treatments (i.e., energy dissipation) did not significantly affect the turbidity and total suspended solids (TSS) of the water exiting the basin, which were reduced by up to 29% and 36%, respectively. The chemical treatment was much more effective regardless of the physical treatment, either in combination or alone, reducing turbidity and TSS up to 88% and 84%, respectively. The baffle materials collected much more suspended sediment when PAM was added, with twice as much sticking to the coir than the Pyramat, although overall the latter may be more effective in settling the flocs. The patterns of turbidity and TSS within the basin suggest that only one porous baffle is adequate for PAM-treated water, and that the reduction observed near the outlet was likely floc interception by the sloped wall of the basin outlet. This study provides a relatively simple, inexpensive approach to improving the function of stilling basins for treating turbid water.}, number={5}, journal={Transactions of the ASABE}, author={Bhardwaj, A. K. and McLaughlin, R. A. and Babcock, D. L.}, year={2008}, pages={1645–1652} }