National Academies Press: OpenBook

Identification of Research Needs Related to Highway Runoff Management (2004)

Chapter: Chapter 2 - Department of Transportation Research Preferences

« Previous: Chapter 1 - Introduction
Page 48
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 48
Page 49
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 49
Page 50
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 50
Page 51
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 51
Page 52
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 52
Page 53
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 53
Page 54
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 54
Page 55
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 55
Page 56
Suggested Citation:"Chapter 2 - Department of Transportation Research Preferences." National Academies of Sciences, Engineering, and Medicine. 2004. Identification of Research Needs Related to Highway Runoff Management. Washington, DC: The National Academies Press. doi: 10.17226/13791.
×
Page 56

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

48 CHAPTER 2 DEPARTMENT OF TRANSPORTATION RESEARCH PREFERENCES All 50 state departments of transportation (DOTs) ranked 45 research priority areas identified by lead DOTs and the research team and added information regarding any further preferences with regard to research needs; see Table 2-1. All items on the ranked list had been identified as a high- priority research area by at least one DOT, and in many cases the phrasing for a particular problem statement origi- nated with a DOT. Each area was weighted in order to identify those with the highest positive and the lowest negative preferences. To develop an overall ranking of research preferences, including the priorities of all 50 state DOTs, and to produce sufficient separation of results (minimization of duplicate rankings or ties), researchers assigned the following weightings to reported rankings: • A weight of 4 for high-priority research, • A weight of 2 for medium-priority research, and • A negative weight (-1) for low-priority research. When multiple practitioners from a state DOT participated in suggesting rankings, researchers used the highest ranking assigned to each category, ensuring each research area the best opportunity at being ranked highly and to fully represent the states most avid research interests and priorities. In other words, if one of the state’s leading stormwater practitioners thought it was a high-priority research area for that state, it was listed as high priority. The number of high-priority research areas a state could include was not limited. It should be noted that even low-ranked research priority areas were still high-priority research areas for a small number of DOTs. In addition, the DOTs indicating interest in research topics had a wide geographic dispersal in all cases, without obvious geographic trends. While northern and mountainous states had interests in deicing agent selection criteria (as might be expected), even states with temperate climates such as Arizona and Hawaii expressed moderate interest. Interest in traction sand removal was the most limited to a particular region of the United States, in this case the northern states, though interest extended as far south as Virginia. States in both arid and moist climates placed a priority on mosquito control. Alaska, Hawaii, and Washington were interested in arid region erosion control as were states with much larger arid areas. Interest in small footprint BMPs was a high prior- ity in relatively low-density states as well as high-density ones. Conversely, opportunities for roadside dispersal were of interest in the most densely populated states as well as the more rural ones. Nevertheless, state DOTs may still be inter- ested in identifying fellow agencies with strong interests in seeing research performed in given areas. State DOTs that placed a high or medium priority on research topics in the survey are identified in Table A-2 in Appendix A. For read- ers’ convenience, a summary table of rankings by combined preference for all research priorities is included as Table A-1. 2.1. TOP-RANKED AREAS OF NEEDED RESEARCH: STORMWATER CONTROL FACILITIES AND PROGRAMS The survey yielded some interesting and perhaps sur- prising results given the panel and GKY’s previous empha- sis on research pertaining to receiving water impacts. DOTs expressed the strongest needs and interests in the area of stormwater control facility cost and performance. Out of a total of 45 research areas, all 6 of the top-ranked priority areas addressed evaluation of stormwater control facil- ities and programs; see Table 2-2. • DOTs ranked research on the operations and maintenance costs of BMPs as their highest interest area—only four states ranked it a low-priority research area. Research on operations and maintenance costs was ranked as a high priority by 75% of the DOTs. Evaluation of construc- tion costs of BMPs was ranked 5th and the need for development of a methodology to quantify BMP bene- fits and costs was ranked 4th. • Some of the other strongest interest areas of the DOTs relate to BMP effectiveness, including evaluation of BMP efficiencies, technical feasibility, and new erosion- control technology, which ranked 2nd, 3rd, and 6th. Among new technology evaluation, development of small footprint BMPs was a particular interest area and was ranked 9th. Each of the research areas discussed above was ranked as a high or medium priority by at least 80% (40 out of 50) of the state DOTs.

49 A separately identified category, performance of BMP retrofits/effectiveness (removing constituents of concerns, hydraulic performance, and export of elements to receiving waters), was ranked 15th by state DOT water quality profes- sionals and was still in the top one-third of research priority areas overall. Considerably more research has occurred in this field, though gaps remain. NCHRP 25-20(01), to be completed in January 2005, will involve collecting and eval- uating information on BMP effectiveness and unit treatment process. Other research areas ranked in the top one-half of identi- fied research areas, in order of preference, included • Performance of nonvegetative permanent soil stabiliz- ers for reducing erosion and potential impacts of prod- ucts on stormwater quality; • Applicability and effectiveness of particular low impact development (LID) design methods in linear corridors and for transportation; • Temporary nonvegetative soil stabilization evaluation; Number of State DOTs Ranking Each Research Area Research Areas Pertaining to Evaluation of Stormwater Control Facilities and Programs High Priority (3) Mid-level Priority (2) Low Priority (1) RA N K WEIGHT 4 2 -1 SC O R E 1 Operations and maintenance costs of BMPs 36 10 4 160 2 Construction BMPs efficiencies 37 8 5 159 3 Technical feasibility of BMPs 30 14 6 142 4 Methodology to quantify BMPs benefits and costs 27 17 6 136 5 Construction costs of BMPs 29 12 9 131 6 New erosion control technology evaluation 28 13 9 129 9 Development of small footprint BMPs 22 18 10 114 10 Performance of nonvegetative permanent soil stabilizers for reducing erosion and potential impacts of products on stormwater quality 23 15 11 111 11 Applicability and effectiveness of particular low impact design (LID) methods in linear corridors/for transportation 19 19 9 105 12 Temporary nonvegetative soil stabilization evaluation 23 13 14 104 15 Performance of BMPs retrofits/effectiveness (removing constituents of concerns, hydraulic performance, export of elements to receiving waters) 21 14 15 97 17 Vegetation establishment 20 15 15 95 18 BMPs benefits and constraints in highly urbanized corridors 17 19 12 94 19 Selection of treatment BMPs and documentation of process 18 18 14 94 20 Detention basin design optimization 16 20 14 90 21 Effectiveness of combination of sedimentation, filtration, and chemical addition for stormwater BMPs construction and retrofit projects 17 18 15 89 22 Guidance for seed mixes and effective establishment and maintenance of erosion control vegetation for short-term first growth and long-term establishment 20 13 17 89 29 Soil evaluation process for slope vegetation 13 20 17 75 30 Bypass detention basin design and effectiveness 13 19 17 73 31 LID modeling and design, so that end-of-pipe control systems can be sized accurately 13 18 16 72 34 Design and maintenance of BMPs to reduce mosquito and other vermin populations 15 12 23 61 36 Gross solid removal device design and performance 12 15 23 55 38 Practical and effective ways to improve dissolved metal removal in current systems 9 19 22 52 39 Traction and removal BMPs for snow areas 12 12 26 46 40 Toxicity controls 7 20 22 46 43 Physics and chemistry of BMPs design 5 15 29 21 44 Arid region erosion control 10 5 34 16 45 Viral pathogen indicators and treatment 4 10 34 2 TABLE 2-1 Research areas pertaining to evaluation of stormwater control facilities and programs ranked in priority by state DOTs

• Valid monitoring methods; • Demonstration of the costs and benefits of alternative, offsite, or watershed-based stormwater mitigation; • Best methods for improving stream ecology through water quality BMPs—alternatives to regulating runoff in urban areas; • Vegetation establishment; • BMP benefits and constraints in highly urbanized corridors; • Selection of treatment BMPs and documentation of process; • Detention basin design optimization; • Effectiveness of combination of sedimentation, filtra- tion, and chemical addition for stormwater BMP con- struction and retrofit projects; • Guidance for seed mixes and effective establishment and maintenance of erosion control vegetation for short- term first growth and long-term establishment; • Infiltration guidance to prevent groundwater contami- nation; • Design and maintenance of BMPs to reduce conflicts with endangered and threatened species; • Soil evaluation processes for slope vegetation; • LID modeling and design so that end-of-pipe control systems can be sized accurately; and • Compliance with numeric water-quality standards. Ranked lower in overall priority but still of medium impor- tance to many respondents were “methodologies to deter- mine where flow control of runoff volumes and high-flow durations are appropriate to prevent stream bank erosion in ultra-urban areas.” 2.2. WATERSHED APPROACHES A watershed approach offers the opportunity to plan com- prehensively and offer solutions that promote sustainable and economically productive watersheds. The approach often 50 seeks to ensure the integration of transportation planning and project delivery into statewide watershed recovery efforts and the direction of mitigation dollars toward high-priority watershed recovery efforts in a basin. Of the topics pertaining to a watershed approach, DOTs were interested mostly in a runoff characterization question: what was the contribution of highway runoff to watershed loadings. This was a high-priority research area for more than 50% of all DOTs, and a mid-level priority for another 25%. More than 80% of the DOTs also had a medium- or high-level interest in demonstrating the costs and benefits of alternative, offsite, and watershed-based stormwater mitigation. Methods for improving watershed stream ecology through alternative and perhaps offsite water quality BMPs were of interest to 72% of the DOTs. Also, 70% of the DOTs wanted to see methodologies developed to determine where flow control of runoff volumes and high-flow durations are appropriate to prevent stream bank erosion in ultra-urban areas. Characterizing sites for offsite water quality treatment on a watershed basis is relatively uncommon. A minority of states indicated that they enjoyed some flexibility with miti- gating for stormwater management off site where it would produce greater environmental benefit for the watershed. Although identifying priority investments has the potential to improve environmental outcomes on a watershed basis, the DOTs had a lower interest in how they could improve ecolog- ical productivity elsewhere in the watershed, especially with- out discussion of how they might receive credit (such as mod- ified expectations for onsite BMPs) in exchange for such work. Of watershed-related research questions, the DOTs ranked rel- atively low the ability of watershed or regionally-based enhancements of wet weather storage capacity to improve baseline (high and low flow) hydrology and ecological pro- ductivity downstream and water quality problems due to urbanization and heavy metal concentration in relation to or projected from Total Connected Impervious Area in the watershed. Still, two-thirds ranked the former as a mid- or high-level research priority and more than 60% considered Alternative Mitigation and Stormwater Management Flexibility Number of States Using Number of States Not Using Onsite mitigation 40 10 Offsite (within sub-basin) 26 24 Offsite (within larger watershed) 17 33 Alternative mitigation 12 38 Stormwater banking 7 43 Cross-category trading 3 47 TABLE 2-2 Alternative mitigation and stormwater management flexibility practices in use at state DOTs

the latter as such. Table 2-3 contains a complete list of water- shed research priority areas and rankings. 2.3. RUNOFF CHARACTERIZATION As illustrated in Table 2-4, the highest rankings among state DOT topic areas pertaining to highway runoff charac- terization suggest the DOTs’ interest in research that charac- terizes their responsibilities and where they should devote the most attention: • Contribution of highway runoff to watershed loadings (a high or mid-level priority to 82% the DOTs; ranked 7th), and • Threshold traffic densities below which certain pollu- tants in highway runoff can be considered negligible or irreducible and can be dispersed on roadsides (a high or mid-level priority to 76% of DOTs; ranked 8th). Both of these research questions were characterized as high priorities by more than 50% of the DOTs. To better answer such questions and to address requests of regulatory agencies with relation to the National Pollutant Discharge Elimination System (NPDES) permits and to the total maximum daily 51 load (TMDL) allocations, 70% of the DOTs ranked identifi- cation of valid monitoring methods as a research priority. Ranked lower, but still a priority area to more than 50% of the state DOTs were deicing agent selection criteria. The role of total suspended solids (TSS) and dissolved organic carbon (DOC) in controlling dissolved metal concentration was also an area of interest and ranked 28th. Regulatory pressures are more acute in some areas than in others; water quality prob- lems due to urbanization and heavy metal concentration in relation to or projected from total connected impervious area in the watershed also was ranked relatively low (37th), but this rapid assessment technique is considered promising in areas looking for creative and cost-effective approaches to TMDL allocations and endangered species concerns. Only one-half of the state DOTs indicated that they con- duct stormwater monitoring, perhaps explaining the lower- than-anticipated level of interest in runoff characterization or receiving waters impact assessment. 2.4. IMPACTS TO RECEIVING WATERS Chemical, toxic, and physical impacts on aquatic biota of stormwater discharges—topics at the top of many university researchers’ lists—received only middling interest from DOT Number of State DOTs Ranking Each Research Area Research Areas Pertaining to Watersheds High Priority (3) Mid-level Priority (2) Low Priority (1) RA N K WEIGHT 4 2 -1 SC O R E 8 Contribution of highway runoff to watershed loadings 26 12 11 117 14 Demonstrating the costs and benefits of alternative, offsite, and watershed-based stormwater mitigation 17 21 9 101 16 Best methods for improving stream ecology through water quality BMPs–alternatives to regulating runoff in urban areas 18 18 12 96 24 Methodologies to determine where flow control of runoff volumes and high flow durations are appropriate to prevent stream bank erosion in ultra-urban areas 14 21 12 86 26 Characterization on a watershed basis and the availability and prioritization of sites for constructed wetlands 14 19 14 80 32 The ability of watershed or regionally based enhancements of wet weather storage capacity to improve baseline (high and low flow) hydrology and ecological productivity downstream 13 18 18 70 37 Water quality problems due to urbanization and heavy metal concentration in relation to or projected from total connected impervious area in the watershed 8 21 20 54 TABLE 2-3 Watershed research areas ranked in priority by state DOTs

TABLE 2-4 Research areas pertaining to highway runoff characterization ranked in priority by state DOTs stormwater staff and engineers, in terms of potential for this research to boost performance in achieving water quality goals. Of the 49 responding states, 17 indicated this area was a low priority for them, dragging down the overall rankings. The Environmental Protection Agency’s (EPA’s) adoption of a biological criteria (biocriteria) approach seems to have had less effect on DOT stormwater quality improvement efforts than the standard NPDES program requirements and current or impending 303(d) listings of impaired waters, with associated regulation of potential loadings from highway runoff (U.S. EPA, 1992). Also, in discussion, some of the DOTs questioned the expense of the research and whether or how it ultimately was used. DOTs’ top-ranked research areas pertaining to impacts on receiving waters were ranked between 16th and 25th (none in the top one-third of identified priorities). As indi- cated in Table 2-5, the DOTs’ top interest areas (supported as a mid- or high-level priority by 60–70% of the DOTs) were • Best methods for improving stream ecology through water quality BMPs—alternatives to regulating runoff in urban areas, • Infiltration guidance to prevent groundwater contami- nation, • Methodologies to determine where flow control of run- off volumes and high-flow durations are appropriate to prevent stream bank erosion in ultra-urban areas, and • Design and maintenance of BMPs to reduce conflicts with threatened and endangered species. 52 The DOTs did express an interest in research funding for critical types of receiving systems, namely those already sub- ject to TMDLs or likely to be subject to TMDLs in the future. Of the research priority areas, the following received the fewest high-priority rankings and the most low-priority rankings: • Receiving water temperature changes, • Herbicide runoff characterization, • Physics and chemistry of BMP design, and • Viral pathogen indicators. These areas (like erosion control in arid environments, which also generally received a low ranking) are nevertheless important research areas for a few and are of high regional importance. 2.5. AREAS FOR FURTHER RESEARCH IDENTIFIED BY DEPARTMENTS OF TRANSPORTATION Respondents from the DOTs were asked individually to identify important areas for further research that could lead to an increased ability of the DOTs to improve the quality of stormwater runoff. Their feedback follows in subsequent sections. It is important to note that each bullet represents feedback from a single individual; the DOTs typically did not detail further research needs in exactly the same areas. Con- Number of State DOTs Ranking Each Research Area Research Areas Pertaining to Highway Runoff Characterization High Priority (3) Mid-level Priority (2) Low Priority (1) RA N K WEIGHT 4 2 -1 SC O R E 7 Threshold traffic densities below which certain pollutants in highway runoff can be considered negligible or irreducible and can be dispersed on roadsides 26 15 8 126 8 Contribution of highway runoff to watershed loadings 26 12 11 117 13 Valid monitoring methods 23 12 14 102 28 Role of total suspended solids and dissolved organic carbon in controlling dissolved metal concentration 14 15 11 75 35 Deicing agent selection criteria 14 13 23 59 37 Water quality problems due to urbanization and heavy metal concentration in relation to or projected from total connected impervious area in the watershed 8 21 20 54 42 Herbicide runoff characterization 5 17 27 27 45 Viral pathogen indicators and treatment 4 10 34 2

solidated rankings for all 50 states on 45 topic areas were dis- cussed previously. This section serves as a useful check to see if the wide body of DOTs raised research issues that were not incorporated initially. The DOTs’ individual respondents identified the follow- ing general areas pertaining to stormwater as important to increasing DOT ability to improve water quality: • BMP performance studies specific to DOT operations and to individual states; • Cost–benefit analyses of BMPs and retrofits; • Determination of the water quality benefits of employ- ing source control measures; • Determination of the effectiveness of treatments and if and when they become feasible economically; and • Effectiveness of BMPs, selection criteria, and construc- tion and maintenance costs. These areas, listed separately by state DOTs in the respon- dents’ own words, do not differ significantly from the pre- listed priority areas on which DOT rankings were requested, though the source control area was not listed as such in the initial ranked list. The remaining topics were high-priority research areas as indicated by DOTs in the ranked portion of the survey. Other recurring research needs were easy guides for the best stormwater control measures (by region) and a synthesis of nationwide best practices (structural and nonstructural). 53 Design or Efficiency of Stormwater Management Measures During Construction Individual DOT respondents identified the following top- ics as important areas of needed research that could lead to an increase in their agency’s ability to improve water quality through design or efficiency of stormwater management mea- sures during construction: • Effectiveness of BMPs to control pollutants in construction-related runoff; • Identification of practical means of controlling turbidity; • Quantification of the effectiveness of using mulches or erosion control mixes versus using a silt fence; • Evaluation of productivity and cost-effectiveness of BMP installation; • Performance data on erosion control BMPs; • What to do with the information after you get the data; a decision tree for possible data—how much is enough? • BMP selection guidance based on construction site conditions; • An easy-to-use guide for measures that are best to use, by region; • Protocols (approval processes and specifications) used by other DOTs for use of polymers for erosion and sed- iment control; • The status of all state DOT stormwater management pro- grams; and • A synthesis of best practices. TABLE 2-5 Research areas pertaining to receiving water ranked in priority by state DOTs Number of State DOTs Ranking Each Research Area Research Areas Pertaining to Receiving Waters High Priority (3) Mid- level Priority (2) Low Priority (1) R A N K WEIGHT 4 2 -1 SC O R E 16 Best methods for improving stream ecology through water quality BMPs—alternatives to regulating runoff in urban areas 18 18 12 96 23 Infiltration guidance to prevent groundwater contamination 18 15 16 86 24 Methodologies to determine where flow control of runoff volumes and high flow durations are appropriate to prevent stream bank erosion in ultra-urban areas 14 21 12 86 25 Design and maintenance of BMPs to reduce conflicts with threatened and endangered species 17 15 18 80 27 Chemical, toxicity, and physical impacts to aquatic biota of stormwater discharges 16 16 17 79 32 The ability of watershed or regionally based enhancements of wet weather storage capacity to improve baselines (high and low flow) hydrology and ecological productivity 13 18 18 70 33 Compliance with numeric water quality standards 14 15 21 65 35 Deicing agent selection criteria (considering effects on receiving waters and biota) 14 13 23 59 40 Toxicity controls 7 20 22 46 41 Receiving water temperature change reduction 5 19 25 33

Retrofitting Existing Stormwater Management Measures DOT individual respondents also identified the following topics as the most important areas of needed research that could lead to an increase in their agency’s ability to improve water quality in retrofitting and site selection for retrofitting: • An easy-to-use guide for measures that are best to use, 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- all environmental impacts; • Research on improved flood control downstream of stormwater ponds; • Retrofits in space-limited, ultra-urban areas; • Requirements for below-ground storage of water; and • Watershed assessment and prioritization techniques that incorporate roadway and water resource characteristics. Maintenance of Stormwater Control Measures during Construction DOT individual respondents identified the following top- ics as the most important areas of research that could lead to an increase in their agency’s ability to improve water quality in the area of maintenance of stormwater control measures during construction: • Evaluation of BMP installation cost-effectiveness (effi- cacy of vactron escavator was mentioned as a particular interest area); • Determination of BMPs installation production rate; • Tools to justify costs of action versus no action, for example, match hydraulic need versus time of concen- tration, and storage needs versus human safety; • Selection of BMPs based on construction site conditions; • A synthesis study on the contract administration of storm- water requirements in construction; • Use of best available technology with a focus on the treatment train; • Development of guidance for fertilizer utilization in seeding and turf establishment near sensitive water bod- ies (nutrient runoff prevention); • An easy-to-use guide for measures that are best to use, by region; • A synthesis of best practices and a compilation of applied knowledge; • Effluent management strategies for concrete truck wash- ing; and • Sharing of ways to monitor impacts to environmental controls after runoff events. 54 Post-Construction Maintenance Aspects of Stormwater Management Measures The most important research topics in the area of post- construction maintenance aspects of stormwater management measures that could increase the DOTs’ ability to improve water quality were listed as • An easy-to-use guide for measures that are best to use, by region; • A synthesis of best practices; • An estimation of the need for the additional mainte- nance personnel who are required to maintain properly the existing BMPs; • Technology improvements, for example, the need for vactor trucks to be able to clean greater than 80% of sediment and debris from catch basins, structures, and manholes; • Testing methodologies for maintenance of stormwater BMPs and specifications for effective use, for example, vacuum sweeper testing methodology and specifications to improve water quality; • Mulches and erosion-control mixes; • Data on maintenance requirements and frequency for BMPs based on location and land use type; • Design for lifetime maintenance of the project; • Long-term effectiveness of devices; • Lifecycle cost analysis of devices; and • Deicing effects on threatened and endangered species, amphibians, and other sensitive species. Retrofitting and Site Selection on a Watershed Basis Just under one-third of the DOTs have retrofitted existing stormwater facilities for stormwater quality control. DOT individual respondents identified the following topics as the most important areas of needed research that could lead to an increase in their agency’s ability to improve water quality in retrofitting and site selection for retrofitting: • An easy-to-use guide for measures that are best to use, 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- all environmental impacts; • Research on improved flood control downstream of stormwater ponds; • Retrofits in space-limited, ultra-urban areas; • Requirements for below-ground storage of water; and

• Watershed assessment and prioritization techniques that incorporate roadway and water resource characteristics. Watershed Approaches State DOTs listed the following areas as needing more research with regard to alternative mitigation (offsite loca- tion of stormwater mitigation measures) and prioritization on a watershed scale: • A standard method for establishing critical needs within a watershed to prioritize areas for BMP implementation; • The need to establish equivalency and to quantify based on ecosystem or habitat, determining when a threshold is met to select an alternative site; • Mitigation to decrease areas of flooding; • An easy-to-use guide for measures that are best to use, by region; • A synthesis of best practices and a compilation of applied knowledge; and • Use of water quality banking or water quality trading by state DOTs. DOTs also listed watershed-related research priorities under related categories, such as retrofit prioritization. Runoff Characterization DOTs suggested further research on the contribution of runoff to water quality degradation and development of a policy regarding Manning’s “N” for various pipe types and sizes (also listed under the Guidelines and Protocols section in this chapter). Receiving Waters Impact Assessment When asked to identify research needs in their own words, pertaining to impacts on receiving waters, DOT respondents suggested the following: • Atmospheric deposition, • Ambient conditions of receiving waters, • Strategies or models for design and location of BMPs and stormwater retrofits to have the maximum impact on receiving waters, • The BMP standard for abating temperature of water dis- charged to cold water streams, • The contribution of bridge runoff to water quality degradation, • Effectiveness of catch basin hoods, • Effects and effectiveness of underground BMPs, 55 • The use of sound scientific methodology (more than just laboratory data) to determine the effectiveness of underground innovative BMPs in capturing stormwater contaminants, • Bacteria and mosquito survivability and propagation within underground BMPs (especially innovative devices), and • Metals fractionation within underground BMPs (due to anoxic conditions). Guidelines and Protocols Used by State DOTs Many state DOTs have developed design guidelines for BMP selection and development of stormwater management plans. In a few cases, state environmental protection agencies have taken the lead in developing guidelines; guidelines are even outlined in state law. State DOT hydraulic engineers and NPDES staff identified the following as the most impor- tant remaining research areas pertaining to design guidelines: • Design considerations, coordination, and BMP selec- tion and decision support to meet NPDES Phase II requirements; development of standards for protecting different levels of environmental sensitivity; • Documented BMP efficiency and effectiveness informa- tion (including access to BMP research and test results; • Short-term and long-term cost information on BMP performance; • Better tools to model performance in relation to TMDLs; • Maintenance facility BMP design guidance; • Temporary water management design; • Contractual methods to improve BMP implementation, including incorporating BMPs as line items into the contract; • More information on and understanding of techniques for maintaining BMPs; • Policy regarding Manning’s “N” for various pipe types and sizes; • An EMS that ties together many existing standard oper- ating procedures in an operation and maintenance area into one EMS; and • A standard, approved post-construction BMPs inspec- tion and enforcement program for erosion control measures. In a few cases, the research team also was referred to fac- ulty from universities cooperating with the DOTs to perform research. The university researchers indicated the following as unaddressed needs: • Methods and technologies to promote the re-use of stormwater; • Public health-related measures;

• Performance of various proprietary devices under spec- ified criteria—decision support system, data on pollu- tant removal efficiencies of various green/LID/ESBCM technologies, infiltration rates and water quality in exfil- tration devices, and in situ removal of pollutants using replacement media; • Effectiveness of plants in ponds; • Green roofs, injection wells water quality, storm surges along coastal areas as they affect the pollution removal characteristics of ponds, and updated rainfall data; • Phosphorus reduction; • Weir performance; • Effects on receiving waters, in particular, algae blooms related to stormwater discharges; • New technologies and improvements on existing designs for the removal of pollutants to assist in reaching nec- essary pollutant removal levels for TMDLs (sediment, nutrient, and metals reductions) and to respond to the space limitations in ultra-urban environments, including development of biological in situ methods that will treat discharge to TMDL-impaired waters; and • Modeling pollution plumes in a 3-D environment. 56 CONCLUSION The survey yielded some interesting and perhaps surpris- ing results given the panel and GKY’s previous emphasis on research pertaining to receiving water impacts. Although there is arguably a logical progression of activity that often starts with fundamental research, progresses through applied research, addresses technology transfer, and then is applied through proof in practice, DOTs indicated less interest in pri- oritizing continued research on impacts to receiving waters and understanding fundamental physical, chemical, and bio- logical or ecological processes operating in receiving sys- tems and more interest in the immediate questions on BMP costs and effectiveness. The research areas recommended in the executive summary of this report reflect this direction. The survey also pointed out the importance of improving the transfer of available research to practicing transportation staff. For example, BMPs for confined areas and construction- type BMP information were listed as priorities for research. These two areas have received a large degree of research atten- tion already. Therefore, the survey results highlight the need to improve information sharing and dissemination.

Next: Chapter 3 - Review of Published Literature and Potential Research Needs »
Identification of Research Needs Related to Highway Runoff Management Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB's National Cooperative Highway Research Program (NCHRP) Report 521: Identification of Research Needs Related to Highway Runoff Management summarizes significant stormwater management practices and research efforts, and it identifies the most pressing gaps and needs in the current state of knowledge in over more than 30 subject areas. The report includes full research project statements for the topics considered to be of highest priority.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!