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52 TABLE 2-4 Research areas pertaining to highway runoff characterization ranked in priority by state DOTs Number of State DOTs Ranking Research Areas Pertaining to Highway Each Research Area Runoff Characterization SCORE High Mid-level Low RANK Priority Priority Priority (3) (2) (1) WEIGHT 4 2 -1 Threshold traffic densities below which certain pollutants in highway runoff can be considered 7 26 15 8 126 negligible or irreducible and can be dispersed on roadsides Contribution of highway runoff to watershed 8 26 12 11 117 loadings 13 Valid monitoring methods 23 12 14 102 Role of total suspended solids and dissolved 28 organic carbon in controlling dissolved metal 14 15 11 75 concentration 35 Deicing agent selection criteria 14 13 23 59 Water quality problems due to urbanization and heavy metal concentration in relation to or 37 8 21 20 54 projected from total connected impervious area in the watershed 42 Herbicide runoff characterization 5 17 27 27 45 Viral pathogen indicators and treatment 4 10 34 2 stormwater staff and engineers, in terms of potential for this The DOTs did express an interest in research funding for research to boost performance in achieving water quality critical types of receiving systems, namely those already sub- goals. Of the 49 responding states, 17 indicated this area was ject to TMDLs or likely to be subject to TMDLs in the future. a low priority for them, dragging down the overall rankings. Of the research priority areas, the following received The Environmental Protection Agency's (EPA's) adoption the fewest high-priority rankings and the most low-priority of a biological criteria (biocriteria) approach seems to have rankings: had less effect on DOT stormwater quality improvement efforts than the standard NPDES program requirements and · Receiving water temperature changes, current or impending 303(d) listings of impaired waters, with · Herbicide runoff characterization, associated regulation of potential loadings from highway · Physics and chemistry of BMP design, and runoff (U.S. EPA, 1992). Also, in discussion, some of the · Viral pathogen indicators. DOTs questioned the expense of the research and whether or how it ultimately was used. These areas (like erosion control in arid environments, which DOTs' top-ranked research areas pertaining to impacts also generally received a low ranking) are nevertheless on receiving waters were ranked between 16th and 25th important research areas for a few and are of high regional (none in the top one-third of identified priorities). As indi- importance. cated in Table 2-5, the DOTs' top interest areas (supported as a mid- or high-level priority by 6070% of the DOTs) were 2.5. AREAS FOR FURTHER RESEARCH · Best methods for improving stream ecology through IDENTIFIED BY DEPARTMENTS water quality BMPs--alternatives to regulating runoff OF TRANSPORTATION in urban areas, · Infiltration guidance to prevent groundwater contami- Respondents from the DOTs were asked individually to nation, identify important areas for further research that could lead · Methodologies to determine where flow control of run- to an increased ability of the DOTs to improve the quality of off volumes and high-flow durations are appropriate to stormwater runoff. Their feedback follows in subsequent prevent stream bank erosion in ultra-urban areas, and sections. It is important to note that each bullet represents · Design and maintenance of BMPs to reduce conflicts feedback from a single individual; the DOTs typically did not with threatened and endangered species. detail further research needs in exactly the same areas. Con-
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53 TABLE 2-5 Research areas pertaining to receiving water ranked in priority by state DOTs Number of State DOTs Research Areas Pertaining to Ranking Each Research Area SCORE Mid- RANK Receiving Waters High Low level Priority Priority Priority (3) (1) (2) WEIGHT 4 2 -1 Best methods for improving stream ecology 16 through water quality BMPs--alternatives to 18 18 12 96 regulating runoff in urban areas Infiltration guidance to prevent groundwater 23 18 15 16 86 contamination Methodologies to determine where flow control of runoff volumes and high flow 24 14 21 12 86 durations are appropriate to prevent stream bank erosion in ultra-urban areas Design and maintenance of BMPs to reduce 25 conflicts with threatened and endangered 17 15 18 80 species Chemical, toxicity, and physical impacts to 27 16 16 17 79 aquatic biota of stormwater discharges The ability of watershed or regionally based enhancements of wet weather storage 32 13 18 18 70 capacity to improve baselines (high and low flow) hydrology and ecological productivity Compliance with numeric water quality 33 14 15 21 65 standards Deicing agent selection criteria (considering 35 14 13 23 59 effects on receiving waters and biota) 40 Toxicity controls 7 20 22 46 Receiving water temperature change 41 5 19 25 33 reduction solidated rankings for all 50 states on 45 topic areas were dis- Design or Efficiency of Stormwater cussed previously. This section serves as a useful check to Management Measures During Construction see if the wide body of DOTs raised research issues that were not incorporated initially. Individual DOT respondents identified the following top- The DOTs' individual respondents identified the follow- ics as important areas of needed research that could lead to ing general areas pertaining to stormwater as important to an increase in their agency's ability to improve water quality increasing DOT ability to improve water quality: through design or efficiency of stormwater management mea- sures during construction: · BMP performance studies specific to DOT operations · Effectiveness of BMPs to control pollutants in and to individual states; construction-related runoff; · Costbenefit analyses of BMPs and retrofits; · Identification of practical means of controlling turbidity; · Determination of the water quality benefits of employ- · Quantification of the effectiveness of using mulches or ing source control measures; erosion control mixes versus using a silt fence; · Determination of the effectiveness of treatments and if · Evaluation of productivity and cost-effectiveness of and when they become feasible economically; and BMP installation; · Effectiveness of BMPs, selection criteria, and construc- · Performance data on erosion control BMPs; tion and maintenance costs. · What to do with the information after you get the data; a decision tree for possible data--how much is enough? These areas, listed separately by state DOTs in the respon- · BMP selection guidance based on construction site dents' own words, do not differ significantly from the pre- conditions; listed priority areas on which DOT rankings were requested, · An easy-to-use guide for measures that are best to use, though the source control area was not listed as such in the by region; initial ranked list. The remaining topics were high-priority · Protocols (approval processes and specifications) used research areas as indicated by DOTs in the ranked portion by other DOTs for use of polymers for erosion and sed- of the survey. Other recurring research needs were easy iment control; guides for the best stormwater control measures (by region) · The status of all state DOT stormwater management pro- and a synthesis of nationwide best practices (structural and grams; and nonstructural). · A synthesis of best practices.
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54 Retrofitting Existing Stormwater Management Post-Construction Maintenance Aspects Measures of Stormwater Management Measures DOT individual respondents also identified the following The most important research topics in the area of post- topics as the most important areas of needed research that construction maintenance aspects of stormwater management could lead to an increase in their agency's ability to improve measures that could increase the DOTs' ability to improve water quality in retrofitting and site selection for retrofitting: water quality were listed as · An easy-to-use guide for measures that are best to use, · An easy-to-use guide for measures that are best to use, by region; · A synthesis of best practices; by region; · · A synthesis of best practices; Models or data, or both, that will help distribute limited funding for retrofits that will achieve the greatest over- · An estimation of the need for the additional mainte- all environmental impacts; nance personnel who are required to maintain properly · Research on improved flood control downstream of the existing BMPs; stormwater ponds; · Technology improvements, for example, the need for · Retrofits in space-limited, ultra-urban areas; vactor trucks to be able to clean greater than 80% of · Requirements for below-ground storage of water; and sediment and debris from catch basins, structures, and · Watershed assessment and prioritization techniques that manholes; incorporate roadway and water resource characteristics. · Testing methodologies for maintenance of stormwater BMPs and specifications for effective use, for example, vacuum sweeper testing methodology and specifications to improve water quality; Maintenance of Stormwater Control Measures · Mulches and erosion-control mixes; during Construction · Data on maintenance requirements and frequency for DOT individual respondents identified the following top- BMPs based on location and land use type; · Design for lifetime maintenance of the project; ics as the most important areas of research that could lead to · Long-term effectiveness of devices; an increase in their agency's ability to improve water quality in the area of maintenance of stormwater control measures · Lifecycle cost analysis of devices; and during construction: · Deicing effects on threatened and endangered species, amphibians, and other sensitive species. · Evaluation of BMP installation cost-effectiveness (effi- cacy of vactron escavator was mentioned as a particular interest area); Retrofitting and Site Selection · Determination of BMPs installation production rate; on a Watershed Basis · Tools to justify costs of action versus no action, for example, match hydraulic need versus time of concen- Just under one-third of the DOTs have retrofitted existing tration, and storage needs versus human safety; stormwater facilities for stormwater quality control. DOT · Selection of BMPs based on construction site conditions; individual respondents identified the following topics as the · A synthesis study on the contract administration of storm- most important areas of needed research that could lead to an water requirements in construction; increase in their agency's ability to improve water quality in · Use of best available technology with a focus on the retrofitting and site selection for retrofitting: treatment train; · Development of guidance for fertilizer utilization in seeding and turf establishment near sensitive water bod- · An easy-to-use guide for measures that are best to use, ies (nutrient runoff prevention); by region; · An easy-to-use guide for measures that are best to use, · A synthesis of best practices; by region; · Models or data, or both, that will help distribute limited · A synthesis of best practices and a compilation of applied funding for retrofits that will achieve the greatest over- knowledge; all environmental impacts; · Effluent management strategies for concrete truck wash- · Research on improved flood control downstream of ing; and stormwater ponds; · Sharing of ways to monitor impacts to environmental · Retrofits in space-limited, ultra-urban areas; controls after runoff events. · Requirements for below-ground storage of water; and
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55 · Watershed assessment and prioritization techniques that · The use of sound scientific methodology (more than incorporate roadway and water resource characteristics. just laboratory data) to determine the effectiveness of underground innovative BMPs in capturing stormwater contaminants, Watershed Approaches · Bacteria and mosquito survivability and propagation within underground BMPs (especially innovative State DOTs listed the following areas as needing more devices), and research with regard to alternative mitigation (offsite loca- · Metals fractionation within underground BMPs (due to tion of stormwater mitigation measures) and prioritization on anoxic conditions). a watershed scale: · A standard method for establishing critical needs within Guidelines and Protocols Used by State DOTs a watershed to prioritize areas for BMP implementation; · The need to establish equivalency and to quantify based Many state DOTs have developed design guidelines for on ecosystem or habitat, determining when a threshold BMP selection and development of stormwater management is met to select an alternative site; plans. In a few cases, state environmental protection agencies · Mitigation to decrease areas of flooding; have taken the lead in developing guidelines; guidelines are · An easy-to-use guide for measures that are best to use, even outlined in state law. State DOT hydraulic engineers by region; and NPDES staff identified the following as the most impor- · A synthesis of best practices and a compilation of applied tant remaining research areas pertaining to design guidelines: knowledge; and · Use of water quality banking or water quality trading by · Design considerations, coordination, and BMP selec- state DOTs. tion and decision support to meet NPDES Phase II requirements; development of standards for protecting DOTs also listed watershed-related research priorities different levels of environmental sensitivity; under related categories, such as retrofit prioritization. · Documented BMP efficiency and effectiveness informa- tion (including access to BMP research and test results; · Short-term and long-term cost information on BMP Runoff Characterization performance; · Better tools to model performance in relation to TMDLs; DOTs suggested further research on the contribution of · Maintenance facility BMP design guidance; runoff to water quality degradation and development of a · Temporary water management design; policy regarding Manning's "N" for various pipe types and · Contractual methods to improve BMP implementation, sizes (also listed under the Guidelines and Protocols section including incorporating BMPs as line items into the in this chapter). contract; · More information on and understanding of techniques for maintaining BMPs; Receiving Waters Impact Assessment · Policy regarding Manning's "N" for various pipe types and sizes; When asked to identify research needs in their own words, · An EMS that ties together many existing standard oper- pertaining to impacts on receiving waters, DOT respondents ating procedures in an operation and maintenance area suggested the following: into one EMS; and · A standard, approved post-construction BMPs inspec- · Atmospheric deposition, tion and enforcement program for erosion control · Ambient conditions of receiving waters, measures. · Strategies or models for design and location of BMPs and stormwater retrofits to have the maximum impact In a few cases, the research team also was referred to fac- on receiving waters, ulty from universities cooperating with the DOTs to perform · The BMP standard for abating temperature of water dis- research. The university researchers indicated the following charged to cold water streams, as unaddressed needs: · The contribution of bridge runoff to water quality degradation, · Methods and technologies to promote the re-use of · Effectiveness of catch basin hoods, stormwater; · Effects and effectiveness of underground BMPs, · Public health-related measures;
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56 · Performance of various proprietary devices under spec- CONCLUSION ified criteria--decision support system, data on pollu- tant removal efficiencies of various green/LID/ESBCM The survey yielded some interesting and perhaps surpris- technologies, infiltration rates and water quality in exfil- ing results given the panel and GKY's previous emphasis on tration devices, and in situ removal of pollutants using research pertaining to receiving water impacts. Although replacement media; there is arguably a logical progression of activity that often · Effectiveness of plants in ponds; starts with fundamental research, progresses through applied · Green roofs, injection wells water quality, storm surges research, addresses technology transfer, and then is applied along coastal areas as they affect the pollution removal through proof in practice, DOTs indicated less interest in pri- characteristics of ponds, and updated rainfall data; oritizing continued research on impacts to receiving waters · Phosphorus reduction; and understanding fundamental physical, chemical, and bio- · Weir performance; logical or ecological processes operating in receiving sys- · Effects on receiving waters, in particular, algae blooms tems and more interest in the immediate questions on BMP related to stormwater discharges; costs and effectiveness. The research areas recommended in · New technologies and improvements on existing designs the executive summary of this report reflect this direction. for the removal of pollutants to assist in reaching nec- The survey also pointed out the importance of improving essary pollutant removal levels for TMDLs (sediment, the transfer of available research to practicing transportation nutrient, and metals reductions) and to respond to the staff. For example, BMPs for confined areas and construction- space limitations in ultra-urban environments, including type BMP information were listed as priorities for research. development of biological in situ methods that will treat These two areas have received a large degree of research atten- discharge to TMDL-impaired waters; and tion already. Therefore, the survey results highlight the need · Modeling pollution plumes in a 3-D environment. to improve information sharing and dissemination.