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122 from highways. The studies reviewed indicate that snowmelt 3.5. RECEIVING WATERS runoff, especially during the first major snowmelt runoff IMPACT ASSESSMENT events of the year, often have highly elevated pollutant con- centrations. Still, because of the hydrological complexity of This category refers to studies conducted in receiving snowmelt and freeze phenomena, it is difficult to monitor waters, including mixing zones. Thirty-five state transporta- and characterize snowmelt runoff events. One alternative is tion agencies have performed some research on impacts on to collect snow samples from roadsides, melt them, and then receiving waters. This section presents research that seeks to analyze them. This approach, however, is highly subjective address the impacts of beneficial uses on receiving waters. According to Pitt et al. (2002) beneficial uses of receiving and dependent on the age of the snow. It may overrepresent waters can be summarized as actual snowmelt concentrations, since it is likely that not all of the pollutants present in the roadside snow will become Stormwater conveyance, mobilized during melting periods. Based on these difficulties, Biological uses, there is an apparent need for guidance on monitoring roadside Noncontact recreation, and snow as well as snowmelt runoff. Developing models that can Contact recreation. be used to predict the occurrence of a snowmelt runoff event would be helpful in determining when monitoring should take Other beneficial uses include drinking water, domestic ani- place. Also, the performance and feasibility of stormwater mal drinking water, crop irrigation, and fisheries. Urbaniza- BMPs during cold weather need to be evaluated. Another tion often leads to changes in the physical, chemical, and bio- issue faced by cold weather stormwater managers is the man- logical characteristics of receiving waters. These changes agement of removed snow from urban highways. often result in habitat that is significantly different from the habitat to which aquatic life is accustomed (May, 1998). Increased impervious area and degradation of water quality 3.4.10.2. Primary References are traits that accompany urbanization. These traits can have negative impacts on stream morphology, in-stream habitat, Caltrans. Tahoe Highway Runoff Characterization and Sand Trap wetlands, and aquatic biota. Transportation development Effectiveness Studies: 20012002 Monitoring Session. Report contributes to that increase in impervious area, in addition No. CTSW-RT-02-044, Stormwater Division (2002). to contaminants generated from highway construction, main- Cristina, C., Tramonte, J., and J. J. Sansalone. A Granulometry- tenance, and usage. Such contaminants include deicers, met- Based Selection Methodology for Separation of Traffic-Generated als, petroleum-related organic compounds, sediment, and Particles in Urban Highway Snow-melt Runoff. Water, Air and agricultural chemicals (Buckler and Granato, 1999). Soil Pollution, Vol. 136, No. 1-4 (2001) pp. 3353. Since 1879, USGS has played a vital role in monitoring and Hatch, L. K., Reuter, J. E., and C. R. Goldman. Daily Phosphorus assessing surface and ground water. USGS activities, studies, Variation in a Mountain Stream. Water Resources Research, Vol. 35, No. 12 (1999) pp. 37833791. and programs provide support for decision making at all lev- Oberts, G. L., Marsalek, J., and M. Viklander. Review of Water els of government. According to Gail and Pixie (2002), USGS Quality Impacts of Winter Operation of Urban Drainage. Water contributions to receiving waters impact research include Quality Research Journal of Canada, Vol. 35, No. 4 (2002) pp. 781808. Monitoring more than 40 watersheds from 1980 to 1996 Oberts, G. L. The Search for Effective Cold Climate BMPs. Proc., as part of nutrient transport studies in the Mississippi American Water Resource Association Spring Specialty Confer- River Basin, ence, Water Resources in Extreme Environments (2000) pp. Conducting studies in San Francisco Bay for more than 147153. 26 years to assess impacts to aquatic biota in the context Sansalone, J. J., and D. W. Glenn III. Accretion of Pollution in of environmental and meteorological changes, and Roadway Snow Exposed to Urban Traffic and Winter Storm Pioneering studies on the impacts of MTBEs. Maintenance Activities--Part I. ASCE Journal of Environmental Engineering, Vol. 128, No. 2 (2001) pp. 151166. USGS also has pioneered the use of several techniques use- Sansalone, J. J., and S. G. Buchberger. Characterization of Solid ful for assessing receiving waters impact, including ground- and Metal Element Distributions in Urban Highway Stormwater. water age dating, and maintains a large database containing Water Science and Technology, Vol. 36, No. 7-8 (1997) pp. 155160. chemical data from more than 335,000 waterbodies (Gail and Smith, D. W., Facey, R. M., Novotny, V., and D. A. Kuemmel. Pixie, 2002). USGS and the Delaware River Basin Commis- Management of Winter Diffuse Pollution from Urban Areas: sion, funded by the New Jersey DEP, conducted a study to Effect of Drainage and Deicing Operations. Cold Regions Impact investigate the impacts of urbanization of five watersheds in on Civil Works (2000). New Jersey. The objective of the study was to assess the cur- Thorolfsson, S. T. New Strategies in Stormwater-Meltwater Man- rent state of water quality, habitat, and stream morphology; agement in the City of Bergen, Norway. Water Science and Tech- develop and evaluate watershed assessment methods; and nology, Vol. 39, No. 2 (1999) pp. 169176. develop goals and objectives for the watersheds. The study,

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123 summarized in a report by Albert and Limbeck (2000), beyond the realm of stream crossings, it is more appropri- reviewed the effects of urban runoff on stream channel sta- ately addressed in the next section. The discussion here is bility, water quality, aquatic organism habitat, and macro- limited to the potential impacts of roadway runoff at stream invertebrates. The authors observed that percent impervious- crossing on aquatic biota. ness is a good indicator of receiving water impacts and Data and analytical methods are available to predict the impervious area mitigation using BMPs may be pivotal to runoff constituents and concentrations for highway and water- successful watershed management strategies. Percent of con- way scenarios. NCHRP Projects 25-13 and 25-13(02) devel- nected impervious surface is still more precise, when such oped guidelines on how to use these data and methods to information is available. make comprehensive assessments of the impacts of bridge runoff on receiving waters and a guide to assist practitioners in making decisions on the need for, and the extent of, con- 3.5.1.1. Primary References trol of bridge-deck runoff in both new and retrofit applica- tions (Dubois, 2002a and 2002b). These projects integrated Albert, R. C., and R. L. Limbeck. High Flow Management Objec- tives for New Jersey Non-Coastal Waters: A Study of the Dela- known technology applicable to the quality of runoff water, ware, Saddle, Whippany, and Musconetcong Rivers and Flat the background quality of the receiving water, and the water Brook. Delaware River Basin Commission, West Trenton, NJ quality criteria applicable to the receiving water and addressed (2000) 34 pp. reasonable treatments and proper disposal systems if and Buckler, D. R., and G. E. Granato. Assessing Biological Effects when warranted. from Highway-Runoff Constituents. Open-File Report 99-240, The guidebook encompassed consideration of runoff con- U.S. Geological Survey, Washington, DC (1999) 45 pp. stituents (e.g., metals, sediments, and nutrients), types of Gail, E. M., and A. H. Pixie. Monitoring and Assessing Our bridge runoff-management designs, impacts on receiving Nation's Water Quality. Fact Sheet 076-02, U.S. Geological Sur- waters and aquatic biota, and other potential runoff impacts. vey, Washington, DC (August 2002) 6 pp. May, C. W. The Cumulative Effects of Urbanization on Small Stream Also included in the guidebook were a risk assessment for Watersheds in the Puget Sound Lowland Ecoregion. Proc., Water special potential problems, benefit and cost-effectiveness Environment Federation, Watershed Management--Moving from assessments, and other elements of a strong management Theory to Implementation, Denver, CO (May 36, 1998). process to streamline and normalize consideration of runoff Pitt, R., Hoffman, D., Rattner, B., Burton, G. A. Jr., and J. Cairns, concerns within the project development process. Where Jr. Receiving Water Impacts Associated with Urban Runoff. warranted, the process addressed a range of mitigation alter- Handbook of Ecotoxicology, 2nd Edition, CRC-Lewis, Boca natives from on-site control of bridge deck runoff to off-site Raton, FL (2002). watershed-based mitigation and pollution trade-off opportu- nities. Where on-site control is proposed, appropriate new 3.5.2. Stream Crossings bridge design parameters for runoff and opportunities for existing bridge retrofits were considered along with non- Stream crossings are especially vulnerable to pollution structural BMPs. from roads. Contaminants such as sediment have easy access Both the design and construction of stream crossing struc- to the underlying streams at stream crossings at every stage tures can impact receiving waters and roadside ecosystems. A in the lifecycle of a road. study of aquatic communities at three bridge sites in Florida Most of the available studies on roadway impacts on was performed by Birkitt and Dougherty (1984). An analy- stream crossings are related to unpaved roads and forest road sis of aquatic communities including dominance, diversity, impacts and bridge construction and maintenance impacts. and evenness values revealed adverse impacts to aquatic biota Areas of interest cited by Taylor et al. (1999) include at one bridge site; the authors attributed the adverse impacts to bridge design practices. Adverse impacts at the second Short- and long-term impacts of stream crossing instal- bridge site were attributed to construction practices. The lations; third site showed only minimal impacts to aquatic biota. The Data from varying stream sizes, soil types, terrain, and authors recommended locating bridges at sites that require climatological conditions; minimum alteration to river channels or the flood plain, using Development of standard measuring methods and con- design principles and construction methods that strive to tinuous automated sampling technologies; maintain existing hydrological, sedimentary, and illumina- Evaluation of proportions of contaminant contribu- tion characteristics of the river system and result in minimum tions from the stream crossing structure and the road site disturbance. A stream relocation and culvert installation approaches; and project presented by Kober and Kehler (1987) found that Stream crossing impacts of stream ecology. incorporating mitigative measures into the project resulted in cost savings. Furthermore, post-construction biological con- Another potential research area is the effect of scour, sed- ditions in the two streams used in the study were similar to imentation, and turbidity on aquatic biota. Since this topic is or better than preconstruction conditions.

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124 Research has shown the presence of heavy metals in bridge and the Auburn University study are available on the TRB runoff. An analysis of runoff from the Skyway Bridge in RIP website. Ontario, Canada, for five heavy metals (zinc, lead, nickel, copper, and cadmium) found EMCs for zinc, copper, and lead to be 0.337 mg/l, 0.136 mg/l, and 0.072 mg/l, respec- 3.5.2.1. Identification of Research Needs tively, in whole water samples. Mean PAH EMCs ranged from 0.015 g/l to 0.5 g/l. Sediment analysis revealed mean con- Receiving waters impacts at stream crossings include centrations of zinc, copper, and lead to be 997 g/g, 314 g/g, impacts that are well beyond the topic of highway runoff, such and 402 g/g. This study by Marsalek et al. (1997) concluded as impacts to stream channel morphology, sonic impacts to that discharging bridge runoff directly into receiving waters aquatic species during pile-driving activities, and impacts to fish passage through culverts. Although further research in without prior treatment could cause significant impacts to these areas may be needed, the focus herein is on highway receiving water bodies. runoff, and the discussion has been limited to impacts caused The preservatives used to treat wood bridges (or compo- directly by stormwater runoff or by runoff generated during nents) often are slowly released into the environment over maintenance activities such as bridge deck cleaning. Other time and could potentially end up in receiving waters. An bridge maintenance activities such as painting, surface treat- evaluation of six bridges--two bridges treated with creosote, ments, substructure repair, joint repair, drainage structures two bridges treated with pentachlorophenol, and another two repair, and pavement repair or repaving also may cause treated with chromated copper arsenate--was performed by impacts to receiving waters depending on storm event tim- Brooks (2000). Study results indicated an absence of PAHs ing, duration, and intensity. With regard to highway runoff, in water near any of the bridges. However, low levels of the potential impacts to receiving waters at stream crossings PAHs were detected in sediment directly underneath the appear to have been assessed by only a limited number of bridges and immediately downstream. An analysis of aquatic studies. NCHRP Project 25-13 is likely the most extensive invertebrate communities did not reveal any adverse effects assessment to date on this topic. and neither did laboratory bioassays conducted on water and The recommended research topics suggest (1) examining sediment. According to the authors, robust invertebrate com- the water quality effects of maintenance practices through munities found in slow-moving streams were not susceptible field studies, (2) developing a bridge deck runoff quality con- to PAH levels that would be expected to impact more sensi- stituents database, (3) applying laboratory bioassays appropri- tive organisms in faster-moving streams. Dilution of con- ate for stormwater discharges and field biosurveys, (4) exam- taminants in the faster-moving streams was found to attenuate ining the potential risks associated with hazardous material contaminant concentrations to levels that were not biologi- spills, and (5) identifying mitigation practices for controlling cally significant. The authors recommended that even though bridge runoff quality. Effects of bridge design and ADT on timber bridges pose little environmental risk, BMPs should runoff quality present another research need. be developed and deployed for all bridge types. A cooperative effort by Auburn University's Biosystems Engineering Department and the U.S. Department of Agri- 3.5.2.2. Primary References culture's Forest Service Southern Research Station and its engineering research work unit in Auburn, Alabama, is under- Birkitt, B. F., and B. J. Dougherty. Effects of Highway Bridges on the way to fill some of the knowledge gaps pertinent to the impacts Aquatic Biota of Three Florida Rivers. In Transportation Research Record 969, TRB, National Research Council, Washington, DC of stream crossings. The objectives of the project include (1984) pp. 17. Brooks, K. M. Assessment of the Environmental Effects Associ- Quantifying and comparing water quality impacts from ated with Wooden Bridges Preserved with Creosote, Pentachlor- different types of stream crossings, ophenol, or Chromated Copper Arsenate. Research Paper FPL Quantifying the amount of sediment produced by road RP587, U.S. Department of Agriculture, Forest Service, Forest approaches at stream crossing sites, and Products Laboratory, Madison, WI (2000) 100 pp. Documenting lifecycle costs of various types of stream Dupuis, T. V. NCHRP Report 474: Assessing the Impacts of Bridge crossings. Deck Runoff Contaminants in Receiving Waters--Volume 1: Final Report, TRB, National Research Council, Washington, DC Another ongoing research effort by the Kentucky Trans- (2002a) 77 pp. Dupuis, T. V. NCHRP Report 474: Assessing the Impacts of Bridge portation Cabinet will evaluate potential receiving water Deck Runoff Contaminants in Receiving Waters--Volume 2: impacts from lead and other heavy metal contaminants gen- Practitioner's Handbook. TRB, National Research Council, erated as a result of pressure washing operations. The study Washington, DC (2002b) 101 pp. also will examine existing paint on the selected bridges to Kober, W. W., and S. E. Kehler. An Analysis of Design Features assess the potential risk to receiving waters. The study will in Mitigating Highway Construction Impacts on Streams. In culminate in the development of alternative practices for Transportation Research Record 1127. TRB, National Research wastewater treatment and disposal. Details of both this study Council, Washington, DC (1987) pp. 5060.

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125 Marsalek, J., Brownlee, B., Mayer, T., Lawal, S., and G. A. Larkin. (4) studying relationships between seasonal timing and effect Heavy Metals and PAHs in Stormwater Runoff from the Skyway of sediment load; and (5) determining whether knowledge of Bridge, Burlington, Ontario. Water Quality Research Journal of survival responses to turbid flows can be used to develop Canada, Vol. 32, No. 4 (1997) pp. 815827. mixing zones, work windows, treatment systems, and buffers Taylor, S. E., Rummer, R. B., Yoo, K. H., Welch, R. A., and J. D. that will allow fish to perform their necessary life functions Thompson. What We Know and Don't Know About Water Qual- during project construction and operation. ity Impacts at Forest Road Stream Crossings. Journal of Forestry, Vol. 97, No. 8 (1999) pp.1217. 3.5.3.2. Primary Reference 3.5.3. Sedimentation and Turbidity Bash, J., Berman, C., and S. Bolton. Effects of Turbidity and Sus- Increases in flow rates to receiving streams caused by pended Solids on Salmonids. Final Research Report No. T1803- Task 42, Effects of Turbidity on Salmon, Washington State Tran- increased impervious areas, in turn, increase the potential for spiration Commission (2001). streams to scour, particularly near outfalls without sufficient energy dissipation controls. Scour can cause increased down- stream turbidity. Poor erosion controls near surface waters, 3.5.4. Toxicity and Bioassessment particularly during and shortly after grubbing and grading activities, can cause sedimentation and high turbidity in Toxicity testing and bioassessments can be used to char- receiving waters. Methods to reduce erosion and turbidity acterize and assess the cumulative/synergistic impacts of were discussed in section 3.2.6. This section addresses the stormwater pollutants on receiving waters and sediments. impact of sedimentation and turbidity on receiving waters. Bioassessment includes evaluating indicators of receiving Research by Bash et al. (2001) evaluated the effects of sed- water health, such as biomass and species diversity. Toxicity iments and turbidity on salmonids in Washington State. A lit- testing requires evaluation of a test species' survivability in a erature review found that excessive sediment in hatchery water sample or sediment sample. The testing is included fre- water may smother eggs by depriving them of oxygen and by quently in water quality management studies, because it can reducing the ability of juveniles to capture prey. The litera- provide an indication of the potential impact of discharged ture review also suggested that gill injuries increase as angu- contaminants on receiving waters and associated biota. larity and particle size of suspended solids increase. The Regulators are attempting to increase regulatory control of authors concluded that a better understanding of sediment toxic contaminants relative to constituents that have low or size, shape, and composition, as well as a better understand- zero toxicity. Knowing the potential toxicity of highway run- ing of salmonid species and life history stages, cumulative off is important, because if toxicity is high, one can expect and synergistic stressor effects, and overall habitat complex- greater regulatory control and the implementation of treat- ity and availability in a watershed is required. They also rec- ment programs to reduce the toxic pollutants. Alternatively, ommend that for short-term construction projects, operators if runoff is demonstrated to be nontoxic, controls subse- must measure background turbidities on a case-by-case basis quently will be reduced. Potential research questions include to determine if they are exceeding regulations. Turbidity standards developed by several states and provinces in the What is the applicability and limitation of the various region attempt to consider natural variability in turbidity by toxicity testing methods with regard to the assessment requiring the regulated community to measure "background of receiving water impacts? turbidity" upstream of any proposed activity. Although, since How can biomass and species diversity be used to eval- the background turbidity measured in these situations repre- uate the health of receiving waters? sents a measurement at one point in time, regulating turbid- ity levels based on this type of measurement may not protect As mentioned in section 3.2.12, information describing salmonid health. toxicity specific to road runoff in the open literature is scarce. Few toxicity studies have been conducted where the runoff 3.5.3.1. Identification of Research Needs was predominantly or exclusively from roadways or high- ways. One multiyear toxicity study was conducted in the With regard to sediment and turbidity impacts to fish in Santa Clara Valley, California; samples were collected pre- general and salmonids in particular, significant research dominantly from freeway runoff. These samples showed high needs identified by Bash et al. (2001) included (1) develop- incidences of toxicity to C. dubia (freshwater crustacean), ing new exposure metrics that account for sublethal effects but the toxic response was quantitatively different from that (as opposed to direct mortality); (2) examining the effect of seen in samples deriving from other land use categories frequent short-term pulses of suspended sediment; (3) con- (BASMAA, 1996). The cause of toxicity for highway runoff ducting additional research on correlations between particle in the BASMAA study was found to be nonpolar organics size, shape, and composition of sediments to fish sensitivity; and metallo-organics. Two other highway runoff toxicity

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126 studies reached similar conclusions on measuring a higher accurately potential toxicity. There was some toxicity with level of toxicity in highway runoff compared to the other 100% runoff from the San FranciscoOakland Bay Bridge land uses [Pitt et al. (1991) and Marsalek et al. (1999)]. The using the time-variable technique. There was significant tox- high level of toxicity in these runoff samples may have been icity with 100% runoff using the traditional 7-day chronic due, in part, to the presence of deicing chemicals or to higher test (did not reflect runoff event length). concentrations of bioavailable heavy metals. Recently, Caltrans initiated a comprehensive toxicity study In addition to water toxicity testing, some researchers have of runoff from their various facilities, including 24 highway evaluated the toxicity of sediments near urban stormwater sites on a statewide basis (Caltrans, 2002). The goal of this outfalls to assess the effects of these discharges. Rochfort Statewide Toxicity Testing Research Project was to assess et al. (2000) assessed relationships among three separate the toxicity associated with discharges from its storm drain aspects of the benthic environment: sediment chemistry (met- system, determine the cause of the toxicity, and provide some als, PAHs, and nutrients) and particle size, sediment toxicity understanding of the sources of these discharges. In most (ten endpoints with four benthic taxa), and benthic inverte- cases, a single discrete sample was obtained from various brate community structure. Researchers found that while con- facilities and tested for toxicity based on the EPA's standard taminant (metals and PAHs) concentrations were relatively three species test. These single discrete samples were col- high in sediments, biological effects were not evident (i.e., lected at different points of the hydrograph with the majority toxicity of sediments was low, benthic communities appeared being collected at the beginning of the storm events. Storm- unaltered, and neither toxicity endpoints nor benthic com- water was captured by grab samples and shipped to the munity descriptors could be related to sediment contaminant Aquatic Toxicology Laboratory at the University of Califor- levels). nia, Davis. The results obtained for the past two monitoring In a similar investigation, the chemical characteristics of seasons (20002001 and 20012002) are summarized below urban stormwater sediments in the rapidly growing Phoenix (Caltrans, 2002). metropolitan area of Maricopa County, Arizona, were ana- lyzed (Parker et al., 2000). Results showed that the inorganic Pimephales--Of the 98 tests performed, 82 (83.7%) component of the sediments generally reflected geologic indicated significant toxicity for either survival or background values, but some metals concentrations (e.g., growth. Significant reductions in biomass were found cadmium, copper, lead, and zinc) were above background in 52 samples, and significant mortality was found in values, indicating an anthropogenic contribution of these ele- 28 samples, indicating that most often, reductions in ments. Organochlorine compounds and PCBs were ubiqui- biomass were common, and acute toxicity was less tous in the sediment samples, even though many of these common. No pattern in toxicity with respect to date of compounds have been banned from general use for as long sampling was apparent, as significant toxicity was found as three decades. Sediment toxicity results seem to suggest at all dates from October to May. that surficial sediments from stormwater-control basins, city Ceriodaphnia--Of the 98 tests performed, 72 (73.5%) streets, vacant lots, and unpaved parking areas are a significant indicated significant toxicity. These results included all environmental problem, but the temporal and spatial variabil- tests for which acute toxicity occurred and chronic tests ity in the test results makes such a conclusion tentative. were not possible to perform. As with the Pimephales' With respect to bioassays for the evaluation of potential toxicity test results, there appeared to be no pattern with toxic effects of highway runoff, Dubois (2002) noted that the respect to date of sampling, as significant toxicity was toxicity test methods should be modified to account for the found throughout the entire period of sampling. episodic nature of runoff; hence, test organisms for bioassays Selenastrum--Of the 98 tests performed, 46 (46.9%) should be exposed to runoff for a length of time equal to the indicated significant toxicity. The Selenastrum test was storm event length. Limitations of traditional toxicity testing never the sole positive test result for any site at any sam- methods also are discussed by Burton et al. (2000). Such ple date. Again, no patterns were evident in the positive time-variable bioassays were performed in the study for run- results. off from two distinct bridges. The I-85 bridge in North Car- Toxicity Identification Evaluations (TIEs)--Thirty TIEs olina, which crosses a small stream, had a medium-level of were performed on samples in which acute toxicity was ADT--74,000 vehicles at the time of the study. The San observed. The TIEs indicated that no single source of FranciscoOakland Bay Bridge, which crosses the San Fran- toxicity was common among sites. However, nonpolar cisco Bay, had a high ADT of 274,000 vehicles at the time of organic compounds were suggested as the putative source the study. No toxicity was found in time-variable bioassays of toxicity in 5 of the TIEs, metals were suggested as for I-85 runoff. Some toxicity was found in traditional chronic the putative source in 11 TIEs, and surfactants were 7-day bioassays with 100% runoff (did not reflect runoff suggested as the putative cause in 7 cases. In one case, event duration). This demonstrates the importance of using a metabolically active pesticide was implicated. The the time-variable technique (described in this report) to assess remainder had no discernable cause.

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127 Overall, more than two-thirds of the discrete samples col- 3.5.4.1. Identification of Research Needs lected were found to be toxic. This method of sample collec- tion and toxicity testing may produce misleading results, as As mentioned above in section 3.2.12, the top two research the single sample is not representative of the entire event. needs identified by GKY and Associates in the original More importantly, the relative toxicity of samples from the NCHRP Project 25-20 report were (1) to identify and develop beginning of the event (first flush) compared with the rest of regional aquatic biological indicators to assess impacts of the event will not be known. Toxicity measurement on a highway runoff and (2) to conduct research methods for hydrographic scale is more appropriate as it would provide assessing the toxicity of highway runoff. This recent litera- information describing the variability of toxicity on a time ture review effort supports the claim that there do not appear and flow scale. to be adequate bioassessment methods for assessing impacts An investigation of the relationship of toxicity to flow and of highway runoff on receiving water systems, particularly at time was initiated as part of the Caltrans first flush study dur- the time-scales typical of stormwater-runoff events. Also, ing the 20022003 monitoring season (Caltrans, 2003). Only there are a wide variety of assessment methods currently three storm events were monitored during the 20022003 wet used by the few highway water quality researchers conduct- season. The results indicate the presence of a toxic first flush ing toxicity and bioassessment studies, so it is difficult to at some sites, which maybe useful for BMP selection. How- quantitatively compare existing data or to make any general ever, results are insufficient to make conclusions regarding assessment of the impacts of highway runoff on receiving the cause of toxicity and the influence of site-specific or water biota. In addition, more within-storm toxicity testing storm-specific factors. Caltrans would like to continue the needs to be conducted to ascertain what parts of storm events first flush toxicity study for two more seasons to address are most toxic. A comparison of drainage systems (e.g., veg- hydrographic toxicity of highway runoff for BMP selection, etated versus piped conveyance) with regard to toxicity is but the availability of future funding is unsure. also a potential research gap. Nbe lkov et al. (2002) studied two tributaries of the Vltava River in Prague in an effort to evaluate the ecological risk of pollutants. They analyzed potential impacts of individual pol- 3.5.4.2. Primary References lutants to aquatic organisms with the aid of mathematical sim- BASMAA. Guidance for Monitoring the Effectiveness of Stormwater ulations. For each pollutant they developed an ecological risk Treatment Best Management Practices. Report, EOA, Inc. (1996). description in toxicological units. The researchers found that Burton, G. A., Pitt, R., and S. Clark. The Role of Traditional and heavy metals did not pose an ecological risk in surface water, Novel Toxicity Test Methods in Assessing Stormwater and Sed- but chronic heavy metal loads were found in bottom sedi- iment Contamination. Critical Reviews in Environmental Science ment, which did pose an ecological risk. & Technology, Vol. 30, No. 4 (2000) pp. 413447. Environmental indicators developed by the Center for Caltrans. Storm Water Monitoring & Data Management: 20012002 Watershed Protection (CWP) can indicate the extent of Annual Data Summary Report. Report No. CTSW-RT-02-048 impacts to receiving water and the effectiveness of storm- (2002). water management programs. The Santa Clara Valley Urban Cloak, D., and J. C. Bicknell. Use of Environmental Indicators for Runoff Pollution Prevention Program implemented and tested Assessing Stormwater Program Effectiveness (2001) 11 pp. 20 of the CWP's 26 Environmental Indicators to Assess Danielson, T. J. Wetland Bioassessment Fact Sheets. Report No. EPA 843-F-98-001, U.S. Environmental Protection Agency, Stormwater Programs and Practices (Cloak and Bicknell, Office of Wetlands, Oceans, and Watersheds, Wetlands Division, 2001). The researchers found that the CWP indicators were Washington, DC (1998). useful for tracking and enhancing pollution prevention Dupuis, T. V. NCHRP Report 474: Assessing the Impacts of Bridge efforts and also for holistic evaluations of stream function for Deck Runoff Contaminants in Receiving Waters--Volume 1: the purposes of watershed management and planning. Final Report. TRB, National Research Council, Washington, DC Bioindicators have been used in studies to demonstrate (2002) 77 pp. impacts to the environment. Lemly and King (2000) used the Lemly, A. D., and R. S. King. An Insect-Bacteria Bioindicator for occurrence of bacterial growth on aquatic insects as an indi- Assessing Detrimental Nutrient Enrichment in Wetlands. Wet- cator of nutrient impacts on wetlands. During field investiga- lands, Vol. 20, No. 1 (March 2000) pp. 91100. tions, nitrate and phosphate levels were linked to the growth Marsalek, J., Rochfort, Q., Brownlee, B., Mayer, T., and M. Servos. of filamentous bacteria on insects. The authors concluded Exploratory Study of Urban Runoff Toxicity. Water Science and Technology, Vol. 39, No. 12 (1999) pp. 3339. that the use of the insect bacteria bioindicator is a reliable Nbe lkov, J., St'astn, G., Komnkov, D., and Z. Handov. Eco- metric for evaluating nutrients impacts on wetlands where logical Risks Assessment of Small Urban Streams. Proc., 9th Wetland Bioassessment Protocols were applicable. Biologi- International Conference on Urban Drainage (2002) 10 pp. cal assessment methods can be used to assess wetland con- Parker, J. T. C., Fossum, K. D., and T. L. Ingersoll. Chemical Char- dition, evaluate the performance of wetland protection and acteristics of Urban Stormwater Sediments and Implications for restoration activities, and track water quality conditions in Environmental Management, Maricopa County, Arizona. Envi- wetlands (Danielson, 1998). ronmental Management, Vol. 26, No. 1 (2000) pp. 99115.

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128 Pitt, R. E., Lalor, M., Field, R., and M. Brown. Investigation of ority; in most of these cases, impacts on cold-water fish Source Area Controls for the Treatment of Urban Stormwater species are a driving factor. Toxicants. Water Science and Technology, Vol. 28, No. 3-5 (1991) Bioavailability of metals in sediments is linked directly pp. 271282. to pore-water metal activity, which is influenced by physi- Rochfort, Q., Grapentine, L., Marsalek, J., Brownlee, B., Reynold- cal, chemical, and biological processes. Wood and Shelly son, T., Thompson, S., Milani, D., and C. Logan. Using Benthic (1999) developed a system dynamics model to represent Assessment Techniques to Determine Combined Sewer Overflow and Stormwater Impacts in the Aquatic Ecosystem. Water Quality these processes and the major influences affecting pore water Research Journal of Canada, Vol. 35, No. 3 (2000) pp. 365397. metal activity in a treatment wetland receiving stormwater influent. The model structure and behavior were tested and validated using several system dynamics validation tech- 3.5.5. Modeling of Water Quality Impacts niques. The model was run using metal specific parameter values typical of metals commonly found in stormwater run- Modeling has become an important part of stormwater off. Simulation results demonstrated that chemical processes management. Nonetheless, modeling development efforts of acid volatile sulfide and organic carbon in binding metal have focused mostly on surface runoff models, and little in reduced sediments are the greatest influences in control- attention has been devoted to developing sophisticated ling metal bioavailability. As represented in the model, the groundwater models. James and Ulan (1997) present dis- effect of bioturbation was negligible. The amount of organic cussions about the utilization of shallow ground routing carbon in the sediment plays the most substantial role in con- routines in SWMM4.3 and HSPF to model infiltration trolling metal bioavailability in the long run. BMPs. Beckers and Frind (2000) developed a model adapted Using 5 years' of highway runoff characterization data, to simulate situations where groundwater recharge may be including 500 storms at nine locations in Washington State, impacted significantly by heterogeneity above the water table. Horner and Mar (1983) developed a model that relates high- The model accepts precipitation and evapo-transpiration as way segment length to cumulative pollutant loadings. The direct inputs. model incorporates the effects of high traffic density and the Hvitved-Jacobsen et al. (1996) simulated oxygen deple- mitigative effects of draining highways through roadside tion from 35 years of rain events using a modified oxygen sag swales. The model can perform three levels of analysis rang- theory. Balmforth et al. (2002) discuss the Leeds Urban Pol- ing from detailed analysis to a simple screening method. lution Management Study, which modeled an area with more than 500,000 people and 130 inadequate combined sewer overflow (CSO) systems. The model was used to gen- erate BOD, ammonia, and suspended solids loads, which 3.5.5.1. Identification of Research Needs then were compared to water quality standards to determine the contribution of individual discharges to the failure of The area of water quality modeling shares a few of the standards. The researchers observed that modeling and data research gaps identified under the BMP Modeling section (sec- collection costs can be reduced through careful management tion 3.2.10) of this effort. These research gaps include the and through the application of the bespoke model. Also, a availability of data for accurate and representative parameter detailed model allows simulation of vital processes such as estimation, the ability to accurately measure and analyze unit first flush. Temperature is a significant water quality pa- processes, model calibration, and the need for an expert sys- rameter for cold-water aquatic habitats. tem for model evaluation and selection. Other potential knowl- Haq and James (2002) present a thermal enrichment model edge gaps pertinent to water quality modeling include guid- for Portage Creek, a cold-water habitat for fish located in ance on modeling temperature change impacts from pavement Portage, Michigan. Using 11/2 years' of continuous tempera- runoff, further development and enhancement of stochastic ture data, they created a model to simulate the heat budget for water quality models, evaluation of the limitations imposed pavement runoff. The researchers concluded that pavement by snow on water quality modeling methodologies, and the runoff impacts stream temperature. development of solutions for more accurate simulation of the Temperature change associated with runoff from paved effects of snow in water quality models. areas has been documented, as has the effect of detention basins on receiving water temperature conditions. However, temperature often is overlooked as a physical characteristic 3.5.5.2. Primary References of receiving waters. It is possible to model temperature effects of urban runoff, but when temperature is related to chemical Balmforth, D., Barker, C., and P. Myerscough. Integrated Model- or biological processes in receiving waters a number of issues ing of CSO Impacts in Large Urban Areas. Global Solutions for are unresolved; available models are often site-specific or lim- Urban Drainage, Proc., 9th International Conference on Urban ited in scope (e.g., addressing only summer season issues). Drainage (2002) 15 pp. Nevertheless half of state DOTs ranked this as a low-priority Beckers, J., and E. O. Frind. Simulating Groundwater Flow and research area. Only 10% of the DOTs ranked it as a high pri- Runoff for the Oro Moraine Aquifer System: Part I--Model For-

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129 mulation and Conceptual Analysis. Journal of Hydrology, Vol. A number of research projects have investigated the impact 229, No. 3 (2000) pp. 265280. of CSOs on receiving waters. Many more monitoring proj- Haq, R., and W. James. Thermal Enrichment of Stream Tempera- ects are still in progress. Kaunelis and Johnson (2000) dis- ture by Urban Stormwater. Proc., 9th International Conference cuss an ongoing evaluation of nine facilities built by the on Urban Drainage (2002) 11 pp. Rouge River National Wet Weather Demonstration Project Horner, R. R., and B. W. Mar. Guide for Assessing Water-Quality Impacts of Highway Operations and Maintenance. In Trans- to store and treat CSO effluent in metropolitan Detroit. The portation Research Record 948, TRB, National Research Coun- results of this effort will determine if more capital investment cil, Washington, DC (1983) pp. 3140. is needed to mitigate CSO impacts. An investigation by Hvitved-Jacobsen, T., Portielje, R., and J. Schaarup-Jensen. Sto- Hvitved-Jacobsen and Harremoes (1981) found that CSO chastic Reliability Methods in Modelling Effects of Urban Pol- impacts on dissolved oxygen occur in two phases. The imme- lution Runoff. Proc., 7th International Conference on Urban diate phase is oxygen depletion attributed to the soluble frac- Storm Drainage (1996) pp. 14911496. tion of organic matter in the discharge. The delayed phase is James, W., and J. A. Ulan. Towards a Shallow Groundwater Rou- potentially more serious and attributed to "adsorption of sol- tine for Modeling Infiltration BMPs in Urban Stormwater Mod- uble, colloidal and fine particulate fractions." Widera and els. Advances in Modeling the Management of Stormwater Podraza (1996) describe chemical analyses as "spot checks" Impacts, Vol 6 (February 1997). Wood, T. S., and M. L. Shelley. A Dynamic Model of Bioavail- that show water quality at a definite time while stream biota ability of Metals in Constructed Wetland Sediments. Ecological analyses reveal long-term effects. Engineering, Vol. 12, No. 3-4 (1999) pp. 231252. Several studies provide insight into CSO effluent composi- tion. The Rouge River National Wet Weather Demonstration Project monitored CSOs for 2 years. Kaunelis and Johnson (2000) summarized the methodology and the results of this 3.5.6. Water Quality Impacts of study. Monitored pollutants included carbonaceous biological Combined Sewer Overflows oxygen demand (CBOD), TSS, ammonia, and total phospho- rus. EMCs for four basins were as follows: CBOD, 4.543.2 CSOs are drainage systems that discharge excess untreated mg/l; TSS, 2482.7 mg/l; ammonia, 0.144.47 mg/l; and total sewage and stormwater directly into marine waters, lakes, phosphorus, 0.581.26 mg/l. The study concluded that the rivers, and other water bodies when the system capacity is reached. In most cases CSOs are legacy systems built in the impacts of CSOs can be isolated from other sources of pol- past and left unchanged as a result of cost constraints. In the lution to quantify the effectiveness of CSO mitigation mea- old days, CSO systems were not considered as a major source sures. Two years' of monitoring data and/or 10 overflow of pollutants; it was assumed that by the time sewage systems events can provide adequate data to support CSO-related overflowed, the majority of the contaminants would have been decision making. Data from a 5-year study of the Cumberland flushed already. Also, the increased volume of the receiving River in Nashville, Tennessee, showed that dissolved oxygen water body was assumed to provide adequate dilution. These depletion was not an issue with the CSO system. This study assumptions are hard to verify (Villeneuve and Lavallee, 1985). by Thackston and Murr (1999) also ruled out the CSO sys- Since the advent of wastewater treatment plants in the tem as the source of the fecal coliform bacteria problem in 1950s, CSO impacts to stormwater have been subject to the river. Data from the study saved $106,000,000 in planned increasing scrutiny. In some municipalities, interceptor pipes redundant improvements to the drainage system. have been built to convey all wastewater, including dis- Seidl et al. (1996) presented a discussion on monitoring data charges from CSOs, to wastewater treatment plants. How- collected as input to run the model Prose and monitored six ever, in many older cities, CSOs still remain an issue. Accord- rainfall events and parameters including conductivity, tur- ing to Seidl et al. (1996), the main impacts of CSOs include bidity, TSS, COD, ammonia, DOC, BOD5, and bacteria. bacteria loads and increased consumption of oxygen due to Researchers found similar ratios between the parameters under organic matter. The water quality impacts of CSOs need to various conditions and concluded that high DOC may origi- be better understood in order to facilitate development of nate from urban surface deposits or resuspension of sewer appropriate regulations for the protection of receiving waters. deposits. They observed a decrease of DOC for the big rainfall According to Kaunelis and Johnson (2000), areas of interest events; they attributed the decrease to dilution. Fluctuations in and research questions concerning CSOs include bacterial levels made observed bacteria biomass level results less conclusive and harder to correlate to other parameters. Is CSO discharge sufficiently clean to meet water qual- A number of studies focus on creating new CSO pollutant ity standards? models or modifying existing models. Hvitved-Jacobsen and What impacts should be measured? Schaarup-Jensen (1990) discussed the application of a dis- How can CSO impacts be isolated and measured inde- solved oxygen stream simulation model. O'Connor et al. pendently of other impacts to receiving waters? (1993) presented a discussion of the use of EPA's SWMM to How much data is needed to support CSO decision model pollutants in a CSO abatement study of Newton Creek making? in New York. Villeneuve and Lavallee (1985) presented

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130 methodologies to characterize CSO wastewater and to define tion evaluates the impacts of deicing agents on stormwater lateral and longitudinal diffusion of wastewater. The paper runoff. Potential research questions include also discussed mitigation of intermittent CSO discharges. Michelbach et al. (1999) presented a method for estimating How do deicing agents impact receiving waters, and nutrient loads to Lake Constance in Europe from CSOs. The what are the least toxic alternatives? authors developed new functions to calculate nutrient loads What factors influence or compound receiving waters from average nutrient concentrations, annual overflow rate, impacts, and how can these factors be minimized? and solids transport in sewers. A comprehensive study performed by Michigan DOT investigated the environmental and economic impacts of de- 3.5.6.1. Identification of Research Needs icing agents. The study includes an analysis of various deicing materials: sodium chloride, calcium magnesium acetate CSO systems are widely variable, and water quality impacts (CMA), Motech, calcium chloride, and proprietary products depend on a host of site-specific parameters. Measurement of such as CMS-B, CG-90 Surface Saver, and Verglimit. Deicers impacts is based mostly on computer simulations. There is a containing chloride salts were found to have similar impacts, need for better monitoring of CSO effluent quality in relation which in turn appear different from impacts from deicers to meteorological factors. What prevailing conditions or fac- containing CMA. The Michigan DOT study and pre-existing tors increase or decrease CSO impacts? What methods can be used to mitigate impacts (structural and nonstructural)? research concur that only in rare situations can road salts cause significant direct impacts. Results from the model developed for the Michigan DOT study suggest that chloride 3.5.6.2. Primary References concentrations in the Great Lakes will not reach toxic levels even in the worst-case scenario; however, chlorides can Hvitved-Jacobsen, T., and K. Schaarup-Jensen. Analysis of CSO cause density stratification in smaller water bodies and CMA Impacts on the Dissolved Oxygen Concentration of Receiving decomposition can lead to depletion of dissolved oxygen lev- Streams. Proc., 5th International Conference on Urban Storm els. The authors suggest diversion of runoff to less sensitive Drainage (June 1990) pp. 517522. areas to attenuate impacts on receiving waters (Public Sector Hvitved-Jacobsen, T., and P. Harremoes. Impact of Combined Sewer Overflow on Dissolved Oxygen in Receiving Streams. Proc., 2nd Consultants, 1993). International Conference on Urban Storm Drainage (June 1981) Other research has been done to investigate the impacts of pp. 226235. deicing agents in correlation to external variables such as Kaunelis, V. P., and C. R. Johnson. Evaluation of In-Stream meteorological and climatological factors. In a study near Impacts of CSO Control Facilities. Proc., Watershed 2000 Con- Jamesville, New York, Champagne (1977) found that pre- ference, Vancouver, BC (2000) 20 pp. cipitation and temperature have an effect on the release of Michelbach S., Weib, G., and H. Brombach. Nutrient Impact from salts into receiving waters. Researchers also found that road CSOs on Lake Constance. Proc., 8th International Conference salts can infiltrate into soils and can impact chloride levels in on Urban Storm Drainage (August 1999) pp. 474481. O'Connor, A., Schuepfer, Z., and L. Kloman. Hydraulic and Pollu- the receiving water long after road salt application. tant Modelling of CSOs Using SWMM's EXTRAN Block. Research on modeling and simulation of the impacts of Proc., 1993 Stormwater and Water Quality Management Model- road salts has been performed in a number of studies. Halm ing Conference (February 1993) pp. 189204. (1997) discussed the development of a finite difference model Seidl, M., Belhomme, G., Servais, P., Mouchel, J. M., and G. De- and its application to airport deicing activities. Lewis (1999) mortier. Biodegradable Organic Carbon and Heterotrophic Bac- conducted an evaluation of the environmental effects of the teria in Combined Sewer during Rain Events. Proc., 7th Interna- deicer magnesium chloride, widely used by Colorado DOT tional Conference on Urban Storm Drainage (1996) pp. 229234. during winter highway maintenance activities. The literature Thackston, E. L., and A. Murr, A. CSO Control Project Modifica- review preceding the investigation indicated that magnesium tions Based on Water Quality Studies. ASCE Journal of Envi- ronmental Engineering, Vol. 125, No. 10 (1999) pp. 979987. chloride deicers are unlikely to produce adverse environ- Villeneuve, J. P., and P. Lavallee. Measured CSO Contribution to mental effects. However, magnesium chloride may contain River Quality Deterioration and Methodologic Approach for other chemicals such as rust inhibitors, which may consist of Negative Influence Evaluation (August 1985) pp. 379422. organic compounds that increase the oxygen demand. These Widera, J., and P.C. Podraza. The Impact of a Combined Sewer Over- chemicals have not been studied adequately. Results of the flow on the Ecology of Benthic Protozoa and Macro-invertebrates Lewis study found that no significant increases in BOD could in a Small Urban Stream. Proc., 7th International Conference on be detected as a result of the addition of 0.3% deicer solution. Urban Storm Drainage (September 1996) pp. 18471852. Biotoxicity testing was conducted on boreal toad tadpoles, juvenile rainbow trout, Ceriodaphnia (aquatic invertebrate), 3.5.7. Deicing Agent Impacts and Selenastrum (algae). Tadpoles and juvenile rainbow trout showed no mortality over 96-hour intervals at deicer con- Deicing agents were discussed briefly under the context of centrations of 0.1%, which is close to the expected median Highway Runoff Characterization and Assessment. This sec- deicer concentration within short distances from the road-

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131 way. Ceriodaphnia had a 48-hour threshold of mortality at that the deicing activities did not adversely impact the three 0.1%, and Selenastrum showed significant suppression of fish food organisms that were quantified. Streambed substrate division rate for algal cells at deicer concentrations slightly analyses indicated that the traction sand used in deicing activ- in excess of 0.1%. The overall conclusion of the study is that ities had no measurable negative impact on known spawning application of magnesium chloride deicer having a chemical locations. The physical, chemical, and biological parameters composition and application rate similar to those typically evaluated in this study indicate that deicing activities along SR used by Colorado DOT is highly unlikely to cause or con- 97 had no measurable negative impact on Peshastin Creek. tribute toward environmental damage at distances greater than 20 yards from the roadway. Even very close to the road- way, the potential of magnesium chloride deicer to cause environmental damage is probably much smaller than that of 3.5.7.1. Identification of Research Needs other factors related to road use and maintenance, including With regard to the receiving water impacts associated with pollution of highway surfaces by vehicles and use of salt and deicing agents, it appears there is a need for a database con- sand mixtures to promote traction in winter. Magnesium taining an evaluation of the human health and receiving chloride deicer may offer net environmental benefits if its use water impacts along with toxicity test results for all existing leads to a reduction in the quantity of salt and sand applied deicing agents to aid in the selection of deicing agents. Other to roadways. potential research needs include the evaluation of the persis- A study on the effects of runoff from Chautauqua Lake tence and implications of various deicing agents in roadside Bridge, in western New York, on sunfish further illustrates soils, evaluation of the factors that influence or compound this toxicity (Adams-Kszos et al., 1990). NaCl appeared to receiving water impacts, and the development of strategies to be the major contributor to the toxicity of runoff from the minimize impacts. Recommendations suggested by Fischel Chautauqua Lake Bridge in laboratory bioassays. However, (2001) include the development and implementation of deic- concentrations of zinc and cadmium present in the 50% win- ing strategies that reduce the amount of chemicals required ter runoff were in the range reported to be toxic to fish and and the development of decision support systems based on may have been additive or synergistic with the NaCl toxicity weather conditions to optimize deicing operations. Minimiz- in the laboratory bioassays. Because runoff from the Chau- ing the amount of deicing chemicals used in deicing opera- tauqua Lake Bridge is diluted greatly when it enters the lake, tions results in a corresponding reduction of the impacts to it is unlikely that bridge runoff will be toxic. However, if receiving waters. runoff comparable to that entering Chautauqua Lake during the winter were to enter a much smaller body of water, the metals and NaCl would probably cause significant harm to freshwater organisms. 3.5.7.2. Primary References The effects of the highway deicing activities on the Peshastin Creek watershed in Washington were studied Adams-Kszos, L., Winter, J. D., and T. A. Storch. Toxicity of Chau- over a 6-month period from December 1999 to May 2000. tauqua Lake Bridge Runoff to Young-of-the-Year Sunfish (Lep- omis macrochirus). Bulletin of Environmental Contamination Steelhead (Oncorhynchus tshawytscha), Chinook salmon and Toxicology, Vol. 45, No. 6 (1990) pp. 923930. (Oncorhynchus mykiss), and bull trout (Salvelinus confluen- Champagne, D. M. Impact of Highway Deicing Salts on Rural tus), three threatened/endangered species, inhabit the stream, Stream Water Quality. In Transportation Research Record 647, and therefore a study of the effects of deicing activities was TRB, National Research Council, Washington, DC (1977) pp. warranted. Five reaches along Peshastin Creek and its tribu- 4752. taries were selected for the collection of weekly grab samples Fischel, M. Evaluation of Selected Deicers Based on a Review of and three of these reaches were outfitted with continuous the Literature. Final Report No. CDOT-DTD-R-2001-15, Col- monitoring equipment. Water quality tests, Microtox toxi- orado Department of Transportation Research Board (October city tests, benthic macro invertebrate enumeration, and stream- 2001) 117 pp. bed substrate sieve analyses were used to evaluate the influ- Halm, M. J. A Finite Difference Model to Predict Stream Water ence of deicing activities (application of traction sand and Quality Impacts as a Result of Airport Deicing Activities. Proc., IceBAN, a liquid deicer) on Peshastin Creek. Chloride exhib- Water Environment Federation 70th Annual Conference and ited signs of preferential elution and was found to be signif- Exposition (October 1822, 1997) pp. 319330. Lewis, W. M. Jr. Studies of Environmental Effects of Magnesium icantly higher in concentration in areas adjacent to the US Chloride Deicer in Colorado. Final Report No. CDOT-DTD-R- Highway 97. The maximum recorded chloride concentration 99-10, Colorado Department of Transportation Research Board, in Peshastin Creek was 3.3 mg/L and 2.7 mg/L at reach 2 and U.S. Department of Transportation, Federal Highway Adminis- reach 4, respectively. The nonimpacted reaches of Peshastin tration (1999) 101 pp. yielded an average chloride concentration of 0.62 mg/L. Public Sector Consultants, Inc. The Use of Selected Deicing Mate- Heavy metals concentrations (soluble and total) were much rials on Michigan Roads: Environmental and Economic Impacts. lower than EPA's recommended limits. The benthic macro Michigan Department of Transportation, Lansing (December invertebrate study, although qualitative in nature, suggested 1993).

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132 3.5.8. Groundwater Quality Analysis while the highest levels for nitrate nitrogen and phosphorus and Impacts were observed near the swales and the exfiltration pipe. Con- taminant concentrations were monitored from 1984 through Increase in impervious area due to urbanization interferes 1986. The results of this Florida DOT study showed an atten- with groundwater recharge. Developed areas that allow some uation of inorganic contaminants; yet, the researchers con- form of infiltration are likely to inject contaminants carried in cluded that organic compounds in the retention pond sedi- surface runoff into groundwater. New sources of groundwater ments may eventually impact groundwater quality. recharge that have resulted from urbanization include domes- Sela (1994) presented graphical methods that were applied tic septic tanks, industrial waste injection wells, agricultural to identify areas of high groundwater sensitivity in a 14-mile- and residential irrigation, and infiltration BMPs (Pitt et al., long highway widening project in New Jersey. This infor- 1994). All of these new sources of groundwater recharge have mation could find potential applications in BMP siting and the potential to cause negative groundwater impacts. After design. development, if most runoff is infiltrated, it is likely that over- Little research has been done on DOT impacts to ground- all infiltration volumes will be higher than before redevelop- water. The most notable DOT groundwater impacts histori- ment, as the water loss from evapotranspiration is reduced. cally have arisen from maintenance yard contamination to Therefore, the potential for increased loadings as well as wells, in which case the DOT has sometimes bought wells, increased concentrations is created. homes, or even larger developments. In Pennsylvania DOT's Widespread adoption and acceptance of infiltration BMPs case, such expensive impacts ultimately led to the agency's as stormwater runoff treatment and control methods have development of ISO14001-certified environmental manage- spawned questions as to whether contaminants are treated adequately before runoff mixes with groundwater. Natural ment systems in maintenance districts. In cases of special organic matter (NOM) present in stormwater reacts with heavy danger where spills contaminate water recharge areas, DOTs metals to form complexes that have shorter transport times. To have been known to develop agreements and "double ditch" investigate the implications of this phenomenon on ground- a facility separating water that came underneath the road from water impacts, Hathhorn and Yonge (1995) performed a two- water that was coming off the highway to prevent any type phase study to investigate heavy metalNOM transport of highway spills from affecting the groundwater and endan- mechanics. They found that dissolved organic matter gered species. enhanced the transport of lead through NOM-metal com- There have been numerous studies on MTBE. MTBE is an plexation. To minimize groundwater impacts, they recom- oxygenate used to increase oxygen levels in gas, thereby mended that in siting an infiltration facility, the organic con- enhancing combustion and decreasing carbon monoxide emis- tent of the soil and the background metal content should be sions (Delzer et al., 1996). In a study to investigate the extent determined. Also, the distance to groundwater should be of MTBE contamination, USGS collected 592 stormwater increased from 3 feet to approximately 10 feet. samples in 16 cities and metropolitan areas from 1991 through A study by Barraud et al. (1999) investigated the potential 1995. The results of this study as summarized by Delzer et al. impacts to groundwater from two soakaway (i.e., underground (1996) detected MTBE in 7% of the samples analyzed. Another injection control) facilities receiving urban runoff. One facil- study presented by Squillace et al. (1996) found MTBE to be ity was 2 years old and one facility was more than 30 years detected most frequently in shallow groundwater; MTBE was old. Groundwater was monitored during storm events 1 m detected in 27% of the 210 shallow groundwater wells sam- and 1.5 m down-gradient from the newer and older facilities, pled in eight areas versus 1% of 412 deep groundwater wells respectively. Soil quality also was measured. The results for sampled in nine areas. A significant number of shallow wells the newer facility indicated that metal and hydrocarbon con- in urban areas were contaminated as compared to shallow centrations were high near the injection surface but decreased wells in agricultural areas. The majority of the studies on rapidly a few decimeters down. However, the older facility MTBE encountered in this effort appear to be centered on indicated that heavy metals and mineral oils can contaminate groundwater. However, the Metropolitan Water District of the soil over a radius of at least 1 meter around the infiltra- Southern California surveyed six reservoirs, which serve as tion facility. Impacts to groundwater were low, but there sources of drinking water in Southern California, to deter- were measurable increases in copper, lead, and zinc concen- mine the level of MTBE impacts. This study by Dale et al. trations as compared to background groundwater concentra- (2000) found that motorized watercraft can be a significant tions. The authors noted that since the data were highly vari- source of MTBE. able and few data points were monitored, it was difficult to Infiltration systems usually are not designed with any draw any definite conclusion from the study. concern for pollution retention. However, it is sometimes In a study to assess impacts of an exfiltration pipe, a proposed that polluted stormwater should pass through a detention pond, a retention pond, and two swales in Florida, humic layer at the soil surface to effectively screen off any Schiffer (1989) found the concentrations of chromium, cop- present well-absorbable or degradable pollutants, whereas per, and lead in groundwater to be below detection limits. clean stormwater should be allowed to infiltrate directly into Groundwater near the ponds had the highest TKN levels, the underground. The implications of such procedures have

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133 not yet been investigated thoroughly, and it is rarely realized Do other oxygenates behave in a similar manner? that they may lead to an unacceptable contamination of sur- How do factors such as land use relate to MTBE occur- face soils. rence? In order to investigate the potential impacts to soil and What are the proportions of contributions from storm- groundwater that have received runoff water from highly water recharge and precipitation to MTBE in ground- trafficked roads for several decades, a field study of a surface water? infiltration system and a subsurface infiltration system was conducted (Mikkelsen et al., 1996). The results of the inves- In summary, the fate and transport of stormwater con- tigation found that the infiltration systems served as effective stituents from BMPs as the constituents move through the pollutant traps for copper, zinc, cadmium, lead, PAHs, and soil mantle and ultimately move through groundwater must adsorbed organically bound halogens, and the potential for be determined. Past guidance for siting infiltration BMPs has groundwater contamination caused by leaching of heavy met- focused on minimum depth to groundwater; however, the fil- als was of low concern. The authors noted that soluble con- tering and sorption capacity of the soils the water passes stituents such as many pesticides and deicing salts may pass through are more important considerations. directly through infiltration systems with little or no retention in the soil matrix and should be investigated further. Differ- ences between the ability of surface and subsurface infiltra- 3.5.8.2. Primary References tion systems to retain pollutants were not found to be signif- icant, but it was indicated that retention capacity was largely Barraud, S., Gautier, A., Bardin, J. P., and V. Riou. The Impact of a function of neutral to weakly alkaline pH conditions, and a Intentional Stormwater Infiltration on Soil and Groundwater. similar observation may not occur in other types of geology. Water Science and Technology, Vol. 39, No. 2 (1999) pp. 185192. Dale, M. S., Koch, B., Losee, R. F., Crofts, E. W., and M. K. Davis. MTBE in Southern California Water. Journal of the American 3.5.8.1. Identification of Research Needs Water Works Association, Vol. 92, No. 8 (2000) pp. 4251. Delzer, C., Zogorski, J. S., Lopes, T. J., and L. R. Bosshart. Occur- Based on the review of literature pertaining to potential rence of the Gasoline Oxygenate MTBE and BTEX Compounds in Urban Stormwater in the United States, 19911995. Water- impacts to groundwater caused by infiltration of stormwater Resource Investigations Report 96-4145 (1996). runoff, there appears to be a need for more research. The Hathhorn, W. E., and D. R. Yonge. The Assessment of Groundwater methods used to assess impacts are difficult to implement, Pollution Potential Resulting from Stormwater Infiltration BMPs. and the results are difficult to assess. State DOTs need a pro- Technical Report WA-RD-389.2, Washington Department of cedure to estimate the potential extent and magnitude of Transportation (August 1995) 181 pp. groundwater quality degradation from transportation BMPs, Mikkelsen, P. S., Haefliger, M., Ochs, M., Jacobsen, P., Tjell, J. C., particularly those that rely on infiltration at their primary and M. Boller. Pollution of Soil and Groundwater from Infiltra- treatment mechanism. This guidance would include proce- tion of Highly Contaminated Stormwater, A Case Study. Proc., dures for identifying and evaluating current and potential 7th International Conference on Urban Storm Drainage (Sep- uses of groundwater and water quality requirements that tember 1996) pp. 707712. could be affected by transportation BMPs. The direction of Pitt, R., Clark, S., and K. Parmer. Protection of Groundwater from flow movement in groundwater aquifers needs to be identi- Intentional and Non-Intentional Stormwater Infiltration. U.S. EPA Report No.EPA/600/SR-94/051 and No.PB94-165354AS, fied. Any pollutant plumes in aquifers must be evaluated, U.S. Environmental Protection Agency Storm and Combined including direction of flow and concentrations. Treated storm- Sewer Program, Cincinnati, OH (May 1994) 187 pp. water quality from transportation BMPs that could infiltrate Schiffer, D. M. Impacts of Stormwater Management Practices on groundwater should be identified in terms of flows, con- Groundwater. Florida Department of Transportation Final Report stituents, and concentrations. The role of geology in pollu- FL/DOT/SMO/90-378 (1989) 79 pp. tant retention appears to be a research gap that needs to be Sela, E. Mitigation of Non-Point Source Pollution Impacts on filled. The distance between BMP invert and the maximum Groundwater Aquifers: A Case Study. Proc., ASCE 1st Annual groundwater elevation must be determined, as must the rate Conference on Water Policy, New York, NY (1994) pp. 246249. of flow downward to the groundwater. Squillace, P. J., Zogorski, J. S., Wilber, W. G., and C. V. Price. A With regard to the persistence of MTBE in groundwater, Preliminary Assessment of the Occurrence and Possible Sources potential research questions and areas of interest outlined by of MTBE in Groundwater of the United States, 199394. Open Delzer et al. (1996) include the following: File Report No. 95-456, U.S. Geological Survey, Washington, DC (1996). How persistent is MTBE in streams, what is the rate of degradation, and what are the potential impacts on 3.5.9. Wetland Impacts aquatic life? What proportions of MTBE are contributions from pre- Wetlands provide numerous benefits that include flood cipitation versus runoff contributions? and erosion control and water quality improvement. Wet-

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134 lands are home to one-third of all federally listed endan- Department of Interior (U.S. Department of the Interior, gered species. Unfortunately, the number of wetlands has 1988 and 1994). Wetland impacts resulting from federal pro- been reduced drastically because of urbanization. Twenty- grams such as agricultural programs; water development and two states have lost approximately one-half of their wet- management programs; infrastructure; local development and lands, while California, Iowa, and Ohio have lost about housing programs; and federal programs to promote resource 90%. The bulk of wetland losses have occurred as a result of use, extraction, and development are presented in the context agricultural conversion, natural erosion, and urbanization-- of regional variability of impacts. The regions studied in the not as a result of highway construction. According to a study report include the Mississippi Delta Region; the Prairie Pot- by Apogee Research Inc. (1997), between 310,000 and hole Region; southeastern Alaska; the Central Valley in Cal- 570,000 acres of wetlands have been lost as a result of ifornia; the Everglades in Florida; Maryland's Eastern Shore; FAHP construction activities between 1955 and 1980. Coastal Michigan; Northern Michigan; the Pocosins in North Replacement costs of such wetlands start between $153 mil- Carolina; New Jersey; the Puerto Rican Mangroves; the Texas lion and $6 billion. A review of the literature pertinent to Coast; and riparian areas in Idaho, Nevada, and New Mexico. wetland impacts reveals that much research has been done The literature has established that highway runoff can have on this subject. However, the discussion herein is limited to a negative impact on wetlands; however, the provision of wetland impacts caused specifically by highway stormwater some form of detention as pretreatment prior to the wetland runoff. The most pertinent research questions with regard to has been shown to significantly alleviate impacts. An evalu- highway runoff are ation by Schiffer (1989) of the effects of highway runoff on two wetlands in central Florida showed that the concentra- To what highway runoff pollutants are natural wetlands tion of automobile-related contaminants and sediment can be most sensitive? reduced by detaining runoff before it is released into wet- Can constructed or mitigated wetlands successfully be lands. Spatial variations of pollutants within the freshwater used to treat highway runoff without impacting local marsh indicated that for most contaminants, concentrations biota? decrease with increasing distance from the inlet. Color, total organic carbon, and chromium concentrations behaved in the The impacts of highway construction and operation on wet- opposite manner. The behavior of chromium may be due to lands have been the subject of a number of studies. Harris the fact that chromium remains dissolved longer than some et al. (1984) discuss a wetland monitoring program devel- of the other metals and could also be linked to atmospheric oped by the Arkansas Highway and Transportation Depart- deposition. The study concluded that detention structures ment to document impacts to a wetland during the construc- larger than the 12-by-25 trash retainer used at the fresh- tion of US-67 in White County Arkansas. Yu et al. (1998) water marsh may provide significant sorption and settling of evaluate two mitigated wetlands constructed by Virginia contaminants, thereby minimizing impacts to wetlands. DOT. Highway runoff provided the primary source of water Mitigated wetlands formed as a result of highway con- for both wetlands. The researchers found that the habitat and struction projects or for economic incentives or wildlife habi- biota remained healthy and diverse for both wetlands. tat creation can provide significant water quality benefits. A Highway operation and maintenance practices that may study (Yu et al., 1998) examined the feasibility of using mit- potentially impact groundwater are likely to impact nearby igated wetlands as stormwater BMPs. Two mitigated wet- wetlands, too. A hydrogeologic investigation (Panno et al., lands were evaluated and monitored during storm events. 1999) indicated the migration of contaminants into two Wetland vegetation density and wildlife diversity were used wetlands via groundwater. The investigation consisted of a as metrics of highway runoff impacts. Peak flow reduction 15-month-long hydrogeologic evaluation of a fen-wetland for both sites was observed to be in excess of 40%. Removal complex in northeastern Illinois. The origin of the high con- rates for TSS, COD, total phosphorous, orthophosphate, and centrations of Na+ and Cl- ions in groundwater plumes zinc were as high as 90%, 65%, 70%, 70%, and 50%, respec- were linked to a private septic tank and road salt operations. tively. Vegetation and wildlife at the two sites were observed Observed impacts to fen vegetation included succession by to be healthy and diverse. According to Knight et al. (1998), salt-loving plant species. Large concentrations of sulphate in the Greens Bayou Wetland Mitigation Bank, implemented the second wetland were linked to oxidation of pyrite within in cooperation with Texas DOT, also was intended to pro- underlying soils. There were no discernable impacts on fen vide stormwater quality mitigation benefits. Approximately vegetation from the high sulphate concentrations. The study 220 acres of wetlands are included in the project. An intricate demonstrated how easily septic systems and deicing opera- train of treatment was included as part of the design to pro- tions could negatively impact wetland vegetation. vide multiple benefits such as highway runoff water quality A comprehensive synthesis of federal programs that impact improvement, flood flow retention, and the creation of wild- wetlands is presented in a two-volume report by the U.S. life habitat. This project will provide treatment for a signifi-

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135 cant portion of the additional flows resulting from the expan- 3.5.9.2. Primary References sion of Beltway 8. Larson and Neill (1987) examined three main biophysical Harris, J. L., Burnside, F. L., Richardson, B. L., and W. K. Welch. Methods for Analysis of Highway Construction Impacts on A elements of wetlands (hydrology, soils, and vegetation) in Wetland Ecosystem--A Multidisciplinary Approach. In Trans- relation to artificial wetlands constructed in fulfillment of mit- portation Research Record 969, TRB, National Research Coun- igation requirements. The importance of each of these ele- cil, Washington, DC (1984) pp. 817. ments to basic wetlands function was evaluated, and the data Hunt, P. G., Stone, K. C., Humenik, F. J., Matheny, T. A., and requirements for assessing the significance of each of the ele- M. H. Johnson. In-Stream Wetland Mitigation of Nitrogen Con- ments were defined. Hunt et al. (1999) discussed the use of an tamination in a USA Coastal Plain Stream. Journal of Environ- in-stream wetland for nitrogen removal in a contaminated mental Quality, Vol. 28 (1999) pp. 249256. Knight, R. L., Adams R., O'Brien, C., and E. R. Davis. Beltway 8 stream. The authors concluded that in-stream wetlands are Wetland Water Quality Project: Constructed Wetlands for Storm- good landscape features that can be used to mitigate excess water Polishing and Wetland Mitigation Banking. In Transporta- nitrogen and are a good complement to other BMPs. tion Research Record 1626, TRB, National Research Council, Washington, DC (1998) pp. 1120. Larson, J. S., and C. Neill. Mitigating Freshwater Wetland Alter- ations in the Glaciated Northeastern United States: An Assess- 3.5.9.1. Identification of Research Needs ment of the Science Base. The Environmental Institute, Vol. 87, No. 1, University of Massachusetts, Amherst (1987) 143 pp. Based on the review of literature, the potential highway Panno, S. V., Nuzzo, V. A., Cartwright, K., Hensel, B. R., and I. G. runoff impacts on natural and mitigated wetlands appear to Krapac. Impact of Urban Development on the Chemical Compo- be well documented. The tendency for many highway runoff sition of Groundwater in a Fen-Wetland Complex. Wetlands, pollutants to accumulate in wetland sediments and vegetation Vol. 19, No. 1 (1999) pp. 236245. Schiffer, D. M. Effects of Highway Runoff on the Quality of Water raises some concern with regard to long-term impacts on wet- and Bed Sediments of Two Wetlands in Central Florida. Water- land biota. Current regulatory requirements for monitoring Resources Investigations Report 88-4200 (1989) 63 pp. and assessing impacts to existing wetlands ensure that water U.S. Department of the Interior. The Impact of Federal Programs on quality and sediment quality, as well as toxicity data, are and Wetlands, Volume 2. A Report to Congress by the Secretary of will continue to become available for analysis. However, as the Interior (March 1994) 333 pp. discussed in section 3.5.4, there is a general lack of applicable U.S. Department of the Interior. The Impact of Federal Programs on bioindicators for evaluating impacts associated with the Wetlands, Volume 1: The Lower Mississippi Alluvial Plain and the Prairie Pothole Region. A Report to Congress by the Secre- episodic nature of stormwater runoff. A potential research tary of the Interior (October 1988) 114 pp. need may be to develop indicators for assessing impacts to Yu, S. L., Earles, T. A., and G. M. Fitch. Aspects of Functional wetlands from highway runoff by conducting a detailed analy- Analysis of Mitigated Wetlands Receiving Highway Runoff. In sis of currently available data on wetlands receiving runoff Transportation Research Record 1626, TRB, National Research from highway facilities. Council, Washington, DC (1998) pp. 2130.