Abstract:
This paper focuses on evaluating natural dispersion runoff infiltration performance by utilizing simulated rainfall-runoff data collected using a field-scale rainfall simulator coupled with a numerical model to study the effects of slope length, angle, and impervious contributory area on natural dispersion applications. A simplified equation was established, termed the LID Design Equation, to analyze natural dispersion performance based on multiple variables that can be determined for site specific conditions, allowing highway engineers to tailor natural dispersion requirements to various locations throughout Washington. Futhermore, the research and resulting evaluation procedure indicate that current evaluation procedures for the use of natural dispersion as a viable stormwater quantity control strategy are not physically accurate.

Authors:
Reister,M., Yonge,D. R.

Keywords:
Low impact, infiltration, highway runoff, stormwater runoff, natural dispersion

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Abstract:
Stormwater injection wells are widely used as stormwater management systems. These wells may act as a low resistance conduit for contaminants transported by stormwater to enter groundwater. This paper summarizes the testing of a natural filtration medium, referred to as a Stormwater Permeable Rapid Infiltration Barrier (SPRIB), that has been proposed as a potential retrofit option for stormwater injection wells in Spokane, Washington, because of its theoretical contaminant attenuation capabilities and its good hydraulic properties. This medium was tested in the laboratory and at a field site using near field-scale columns to determine its useful life span in terms of metal (Cu, Pb, and Zn) removal capacity and maintenance of acceptable infiltration rates. After a series of simulated storm events, the SPRIB demonstrated contaminant concentration reduction rates of total metals greater than 99% and soluble metals from 91% to 98%. Surface clogging of the columns by stormwater particulate matter was shown to be the limiting factor in the useful life span of an unmaintained SPRIB. Based on the observed linear decline in infiltration rates due to sediment loading, the predicted life span of SPRIB is 20 to 22 storms (roughly 6 months in the Spokane area) before infiltration falls below acceptable rates (8 to 12 in/hr). A significantly longer life span is expected if pretreatment for suspended solids or periodic SPRIB maintenance is performed.

Authors:
Yonge,D. R., Roelen,P.

Keywords:
highway runoff, stormwater treatment, dry well, retrofit, research

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External Links: http://www.wsdot.wa.gov/research/reports/fullreports/559.1.pdf http://wsdot.wa.gov/Research/Reports/500/559.1.htm

Abstract:
A 17-month sampling campaign was initiated to investigate the potential for vegetated highway shoulders to retain suspended solids, metals, and total petroleum hydrocarbons. A site along SR 8 in Western Washington was selected and three full-scale test plots constructed for evaluation of contaminant retention capability. The data indicated that TPH and suspended solids were effectively removed. Metal concentration reduction was also effective when consideration was given to inadvertent pretreatment afforded by the highway runoff collection system. Consequently, the vegetated highway shoulder, located along hundreds of miles of highway can afford a cost effective means of contaminant retention.

Authors:
Yonge,D. R.

Keywords:
highway runoff, vegetative filter strips, contaminant retention, metal retention

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Abstract:
Confined spaces BMPs were discussed in regard to hydraulic and pollutant removalperformances. Various filter media having potential for use in filtration vaults were evaluated. Columntests using fifteen types of filter media (aquarium rocks, cedar bedding, charcoal, corn cobs, gardenbark, glass beads, kitty litter, iron oxide coated sand, peat moss, persolite, sand, CH zeolite, XY zeolitesand/steel wool, and WSU compost) were run with a synthetic stormwater runoff influent. Effluentsamples were collected over time and analyzed for cadmium, copper, lead, zinc, nitrate, phosphate, pH,TSS, and TPH. Results indicate that garden bark, peat moss, sand, and WSU compost are the best filtermedia for treating stormwater runoff in vaults. Initially, they have acceptable hydraulic properties topass water through the filters and have good pollutant removal abilities. Over time, however, evidenceof clogging can be seen. Further field testing is recommended to determine actual operation andmaintenance schedules. Design guidelines are included for the recommended filter media.

Authors:
Koob,T. L., Barber,M. E.

Keywords:
highway runoff, pollutant removal, metals, filter media, column studies

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Abstract:
Investigations regarding the introduction of contaminants to the aquatic environment through highway runoff began in the late 1970's. Interest in this area of study has continued to increase, particularly in the area of design, operation, and effectiveness of contaminant mitigation devices. Contaminants of concern in highway runoff include metals, organics, and suspended solids.To determine the effectiveness of these grass strips as a retention mechanism, a full-scale grass strip model was constructed that allowed control of slope and stormwater contaminant feed rate. The model was 1.2 m wide (perpendicular to flow path) and contained a 3 m grass section. A simulated highway stormwater was developed that contained sediment, lead, cadmium, copper, and zinc. The research approach was divided into three main areas: (i) determination of the hydraulic retention time for various slope and flow combination, (ii) estimation of retention times for selected metals, (iii) analysis of the fate of the metal contaminants with regard to spatial location as well as plant uptake. Hydraulic detention time over a range of slope/flow combinations was estimated using a bromide tracer technique.The largest portion of metals were retained within the initial 1 m of the grass strip and 0.4 inches of depth. These analytical findings were supported by visual observations that indicated that the stormwater sediment was retained in the upper 1 m of the grass strip. Overall metal retention was estimated by mass balance and it was determined that 84% of zinc, 93% of lead, and >99% of cadmium and copper applied to the grass strip was retained. Over the duration of nine indivdual storm events, no signifigant metal breakthrough was observed at the test strip outlet or in the first set of monitoring wells placed 0.6m from the stormwater inlet distribution device.

Authors:
Newberry,G. P., Yonge,D. R.

Keywords:
stormwater contaminants, stormwater metal removal, highway runoff, vegetated slopes, grass strips, research

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Abstract:
Washington State has begun a program to dispose of highway runoff in which a priority has been given to the use of infiltration type technologies (e.g. infiltration basins, dry wells, etc.). Heavy metals are the most prevalent priority pollutant in highway runoff. Though traditionally these heavy metals are thought to possess relatively large retardation factors within the subsurface, previous studies have indicated a possibility of their transport being facilitated through complexation with natural organic matter (NOM). If ignored this form of transport may pose serious errors in the prediction of metal(s) breakthough times and mass loadings to underlying groundwaters. In addressing this issue, soil columns were tested under loading conditions similar to actual infiltration BMP's to assess the performance of these facilities in removing heavy metals (Cd, Cu, Pb, Zn) from infiltrating water. Experiments were performed investigating the effects of high and low concentrations of NOM on metals attenuation by field soils. Results show that high concentrations of NOM actually improved soil column performance. The data revealed that metals speciation and background metals present in the soil are important factors to consider, because they can affect expected metals removal rates of soils. The hydraulics of the system played a secondary role to the geochemistry. Results suggest that infiltration can be a viable alternative in disposing of runoff at low metals concentrations. Modifications to guidelines were discussed to improve the long-term performance of infiltrations facilities.

Authors:
Hathhorn,W. E., Yonge,D. R.

Keywords:
infiltration BMPs, highway runoff, heavy metals, facilitated transport, humic substances, research

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Abstract:
Washington State has begun a program to dispose of highway runoff in which a priority has been given to the use of infiltration type technologies (e.g. infiltration basins, dry wells, etc.). Heavy metals are the most prevalent priority pollutant in highway runoff. Though traditionally these heavy metals are thought to possess relatively large retardation factors within the subsurface, previous studies have indicated a possibility of their transport being facilitated through complexation with natural organic matter (NOM). If ignored this form of transport may pose serious errors in the prediction of metal(s) breakthough times and mass loadings to underlying groundwaters. In addressing this issue, soil columns were tested under loading conditions similar to actual infiltration BMP's to assess the performance of these facilities in removing heavy metals (Cd, Cu, Pb, Zn) from infiltrating water. Experiments were performed investigating the effects of high and low concentrations of NOM on metals attenuation by field soils. Results show that high concentrations of NOM actually improved soil column performance. The data revealed that metals speciation and background metals present in the soil are important factors to consider, because they can affect expected metals removal rates of soils. The hydraulics of the system played a secondary role to the geochemistry. Results suggest that infiltration can be a viable alternative in disposing of runoff at low metals concentrations. Modifications to guidelines were discussed to improve the long-term performance of infiltrations facilities.

Authors:
Hathhorn,W. E., Yonge,D. R.

Keywords:
infiltration BMPs, highway runoff, heavy metals, facilitated transport, humic substances

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Abstract:
The Washington State Department of Transportation designs, operates, and maintains stormwater detention basins for flood control. Initiatives by the Washington State Department of Ecology have prioritized the consideration of stormwater quality as well as quantity for stormwater treatment. Modification of existing stormwater detention basins could afford an efficient mechanism for addressing water quality by enhancing contaminant removal.A scale model of a typical basin was constructed to investigate contaminant removal capabilities of existing detention basins. A simulated highway stormwater runoff was fonnulated and applied in scale model detention basin testing over a range of flow rates. Four coagulants were evaluated for their ability to enhance removal of sediment and metals.Coagulant addition resulted in significant increases in metal removal over the range of stormwater flow rates studied. The greatest improvement was observed at the higher flow rates. Enhanced metals removal resulted from increased removal of small particles and their sorbed metals. Further improvement in contaminant removal was observed following the addition of an influent baffle, resulting in improved basin hydraulic characteristics which increased solids detention and minimized short circuiting.

Authors:
Price,F., Yonge,D. R.

Keywords:
stormwater, sediment removal, contaminaint removal, highway runoff

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Abstract:
The Washington State Department of Transportation (WSDOT) designs, operates, and maintains stormwater detention basins. These basins are used to control storm water runoff from highways, thereby controlling flows in down gradient areas. Historically, storm water basin design has been based solely on hydraulic considerations. Recent initiatives by the Washington State Department of Ecology have indicated that storm water quality has become a high priority. Consequently, future design must consider water quality as well as flood control. To have control of the variables associated with removal efficiencies (flow rate, contaminant type, contaminant concentrations, particle size distribution, and basin configuration) a scale model of a typical detention basin was constructed. Experiments to determine removal efficiencies for suspended solids with diameters <75 micrometers were conducted and the results were compared with the Type 1 sedimentation theory for an ideal basin. Preliminary investigations into the removal efficiencies for Pb, Zn, Cd, and Cu were performed at one flow rate and optimized piping configuration. The removal of suspended solids range from 65-80%. Type 1 sedimentation theory for an ideal basin yielded good predictions of sediment removal. This implies that Type 1 sedimentation theory could be used to estimate sediment removal in full scale systems under similar conditions. Care should be taken when predictions are required at high-surface overflow rates or highway runoff that contains a significant fraction of small particles. The removal of metals ranges from 28-40% indicating that removal of smaller particles is necessary to achieve better removal efficiencies for metals.

Authors:
Yonge,D. R., Cole,W. H.

Keywords:
stormwater, sediment removal, contaminaint removal, highway runoff

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Abstract:
This report present the final form of the Washington State Highway runoff pollutant loading model, incorporating data from the five years of study. It also features a probabilistic analysis of concentration and loading data designed to express the chance of exceeding specific values in a given case. Other topics include further assessment of the toxicity of highway runoff and its causes and mitigation.

Authors:
Little,M. L., Horner,R. R., Mar,B. W.

Keywords:
analysis, Assessment, data, highway, highway runoff, ITS, mitigation, model, pollutant loading, runoff, stormwater, Toxicity, Washington, Washington state

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Abstract:
Statewide sampling of highway runoff continued through 1980-81, and the resulting data has been aggregated with that from previous years to further investigate pollutant loadings. Results have validated the solids loading model previously proposed by Asplund (1980) for Western Washington Highways and tentatively extended the model to Eastern Washington. Loading of there pollutants can be predicted from total suspended solids loading using ratios derived from the data. These ratios may be taken as constants at any Washington State location for some pollutants or as linear functions of traffic or other contaminants. Comparison of runoff from a sulfur-extended asphalt pavement with runoff elsewhere indicates higher sulfate loads in the former case. A limited sampling program along an uncurbed highway section observed higher pollutant concentrations from these sections to curbed areas. Sampling of solids adhering to the undercarriage of automobiles produced widely varying results but suggested that vehicles traveling on rural or unpaved roads accumulate significant amounts of solids that can be released on highways. The final year of field sampling will concentrate on improving the loading models, especially for Eastern Washington application, and continuing the sulfur extended asphalt study with a functional control site experiencing the same conditions.

Authors:
Tai Wik,David Chui, Mar,B. W., Horner,R. R.

Keywords:
analysis, asphalt, asphalt pavement, Concentrations, condition, control, data, extended asphalt, highway, highway runoff, Highways, loads, model, models, pavement, pollutant loading, Pollutants, program, runoff, rural, sampling, statistical analysis, sulfur, suspended solids, traffic, Washington, Washington state

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Abstract:
The impacts of storm water runoff from Washington State freeways on aquatic ecosystems were investigated through a series of bioassays utilizing algae, zooplankton and fish.Algae and zooplankton were adversely affected by the soluble fraction of the runoff, while suspended solids caused high mortalities of rainbowtrout fry . In addition,. BOD 5 values similar to those reported in the storm water literature were measured; however, there were indications that results were influenced by toxicity to microbial populations.

Authors:
Portele,G., Mar,B. W., Horner,R. R., Welch,Eugene

Keywords:
Algae, Biochemical Oxygen, Biomass, control, Demand, fish, freeway, heavy metals, highway, highway runoff, impact, impacts, Interim, metals, population, runoff, stormwater, suspended solids, Toxicity, transport, Washington, Washington state, Water Pollutants, Washington State Monitoring, zooplankton

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Abstract:
A highway storm water runoff pollutant loading. model has been developed based on results from con3posire sampling of approximately 600 storms at nine locations in the State of Washington over five years. The model expresses total suspended solids (TSS) loading in proportion to the product of highway segment length, average runoff coefficient, and vehicles traveling during storm periods. It was dem-onstrated that loadings of contaminants such as chemical oxygen demand, nutrients and trace metals could be estimated from TSS loadings using ratios derived from the data, The model described was developed and validated for assessing total loadings over a time span encompassing a number of storms (monthly or annually). To predict pollutant concentrations and loadings in runoff from a given storm, cumulative distributions were plotted and analyzed to determine the probability of exceeding specific concentration and loading values in a given case. Bioassay studies using highway runoff indicated toxicity to aquatic life when elevated metals deposition from high traffic volumes (in excess of 10,000 -20,000 vehicles per day) or high metals concentrations in rainfall caused runoff concentrations to exceed lethal levels. Draining highway runoff through grass channels 60 meters in length greatly reduced TSS and metals concentrations and the consequent toxic effects. The major product of this research is a guide to assessing and mitigating the impacts of highway runoff to receiving waters.

Authors:
Mar,B. W., Horner,R. R., Spyridakis,D. E., Welch,E. B.

Keywords:
Assessment, Channel, Chemical, Concentrations, data, demand, deposition, developed, highway, highway runoff, impact, impacts, Loadings, Highway runoff, metals, mitigation, model, models, pollutant loading, Pollutants, quality, rainfall, research, runoff, sampling, span, stormwater, suspended solids, Toxicity, traffic, traffic volumes, volume, Washington, Washington state, water quality

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Abstract:
This report summarizes findings detailed in Report Nos. 4 and 5 plus the work of Zawlocki on trace organics in highway runoff. Several hundred compounds tentatively, identified by GC-MS were grouped into nine categories, which were not mutually exclusive. Major components of-these 'categories were petroleum products used by vehicles and incompletely combusted hydrocarbons. The concentrations of these trace organics groups were low compared to criteria proposed for protection of aquatic life.

Authors:
Mar,B. W., Ferguson,J. F., Welch,E. B.

Keywords:
Concentrations, construction, criteria, group, highway, highway runoff, Highways, hydrocarbons, Leachate, Organics, petroleum, protection, quality, runoff, Water Pollutants, Washington State Monitoring, water quality, Woodwaste fills

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Abstract:
Trace organics were surveyed using gas chrornotography coupled to mass spectrometry for highway runoff samples from two Seattle sites . The characterization of the organics exhibited concentrations of aliphatic, aromatic and complex oxygenated compounds. Vehicles, including.exhaust emissions, were concluded to be the source of many of the organics.

Authors:
Zawlocki,K. R., Ferguson,J. F., Mar,B. W.

Keywords:
Concentrations, emissions, highway, highway runoff, Interim, Organics, runoff, seattle, survey, Washington, Water Pollutants, Washington State Monitoring

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Abstract:
A composite sampling device was developed that can be installed at less than ten percent of the cost of automatic sampling systems currently used in Federal highway runoff studics. This dcvi ce was operated for one year, along-side an automatic sampler at the 1-5 side, to demonstrate that the two systems provide statistically identical storm composites.

Authors:
Clark,David L., Mar,B. W.

Keywords:
cost, developed, highway, highway runoff, Interim, runoff, sampling, System, systems, Water Pollutants, Washington State Monitoring

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Abstract:
A total of 241 storm events were sampled at ten sites during the first full year of statewide monitoring of highway runoff. Analyses of these data indicates that more than half of the observed solids in this runoff is traced to sanding operations. The total solids loading at each side-was correlated with traffic during the storm. The ratio of other pollutants to solids was linear when there was sufficient traffic-generated pollutants to saturate the available solids.

Authors:
Asplund,Randy L., Ferguson,John F., Mar,B. W.

Keywords:
data, highway, highway runoff, models, monitoring, Pollutants, runoff, traffic, Washington, Washington state, Water Pollutants, Washington State Monitoring

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Abstract:
This report covers the initial 15 months of effort to review the literature, select a prototype site, compare the performance of several automatic sampling devices, and install a prototype sampling site on 1-5 north of Seattle .

Authors:
Horner,R. R., Burges,S. J., Ferguson,J. F., Mar,B. W., Welch,E. B.

Keywords:
highway, highway runoff, Interim, monitoring, performance, review, runoff, sampling, seattle, Water Pollutants, Washington State Monitoring

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Abstract:
Criteria for selecting statewide monitoring sites for highway runoff were established t o provide representative combinations of climate, traffic highway, land use, geographic and topographic characteristics , Using thesecriteria , a minimum of six sites - were recommended for use to this research.

Authors:
Aye,Robert C.

Keywords:
criteria, highway, highway runoff, land use, land-use, monitoring, research, runoff, traffic, Water Pollutants, Washington State Monitoring

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Abstract:
A study was conducted on the character and significance of highway runoff waters for the Washington Department of Highways and the Federal Highway Administration. This preliminary appraisal of runoff quality consisted of a literature review and critique plus a limited amount of field sampling on SR 520. Although a large amount of information is present in the literature concerning urban run off, there is very little strictly related to highways and their rights-of- way. Highway runoff is similar t o urban area runoff but may be higher in heavy metals and oil. A significant fraction of the heavy m e t an l s, oil and nutrients are adsorbed to the dust and dirt fractions and then may be removed by sedimentation. Runoff from the lake bridges should have a very insignificant effect on Lake Washington in comparison with the urban run off to the Lake. Recommendations are made for mitigating runoff effects and for conducting an intensive study of highway run off water quality and its significance.

Authors:
Sylvester,Robert O., DeWalle,Foppe B.

Keywords:
bridge, bridges, environment, heavy metals, highway, highway runoff, Highways, ITS, metals, quality, review, runoff, sampling, sedimentation, Study, urban, vehicle emissions, Washington, water quality

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