Pollutant Load Reductions for Total Maximum Daily Loads for Highways (2013) / Chapter Skim
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Pages 7-35
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7 chapter three RESULTS AND SYNTHESIS The literature review provided key information on state TMDL programs including the types of BMPs being implemented, their effectiveness, design standards, and associated costs. The literature review findings supplemented the information obtained during the interviews and provided a greater level of detail to present a more comprehensive picture of TMDL and BMP implementation strategies.
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8 State DOT No. of TMDLs Where the DOT Is Named as a Stakeholder TMDL Pollutants of Concern Comments Kansas 0 N/A KDOT does not foresee TMDLs being implemented in the near future; it focuses on temporary construction stormwater BMPs only (no retrofits)
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9 One example of an institutional practice is a collaborative approach with the state regulatory agency to TMDL development. As recommended in McGowen et al.
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10 period. The Minnesota DOT (MnDOT)
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11 and responsibilities of each party in inspecting, repairing, and maintaining MS4s, bridges, stormwater management basins and ponds, etc., within their respective jurisdictions. In particular, the IA states that the county and DelDOT shall consider TMDLs and various pollution control strategies as provided in a consent decree.
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12 highway runoff but are less effective at removing nutrients and bacteria. In some cases, the BMPs most likely exported nutrients as a result of fertilizer applications in vegetated BMPs and nitrification in filtration BMPs.
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13 TABLE 4 EXPECTED EFFLUENT CONCENTRATIONS FOR BMP TYPES From Caltrans (2004)
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14 for the water quality design storm because they have no effluent discharge. An example graph for TSS is shown in Figure 2.
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15 Constituent Influent EMC (mg/L) Influent Load (kg)
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16 The total included the runoff entering the system plus the bypass water in order to identify the total load to the receiving waters. As shown, accounting for the bypass reduces the performance (i.e., percent removal)
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17 BMP Type Median (95% Conf. Interval)
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18 one BMP versus another. However, these results should be used cautiously.
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19 • Spill prevention and response plans • Education/awareness for the public and employees. Effectiveness of any of these BMPs depends on a number of factors that have been recognized for over a decade (NVPDC 1996)
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20 urbanized land use back to a more natural landscape. Tree planting is also included in the Maryland Accounting Protocol (MDSHA 2012)
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21 of anti-icing management is a pilot project implemented by NHDOT. The pilot project tests advanced technology to measure the temperature of the road surface and automatically manage the rate of salt application.
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22 different though generally similar level of effort for routine maintenance. Based on the DOT interviews, it is the uncertain financial and manpower estimates associated with the infrequent maintenance and the potential for major overhaul of the BMPs that in part fuels the resistance of implementing the new practices.
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23 here; however, the reader is encouraged to refer to the full reports for additional details. Design Costs There was generally little information available in the literature on design costs.
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24 • Infiltration Trench CC = 44.108 WQV-0.1991 • Sand Filter CC = 389.00 WQV-0.3951 • Bioretention CC = 0.0001 WQV + 9.00022 • Grass Swales CC = 21.779 ln(A) - 42.543 Where CC is the construction cost expressed in dollars per unit of water-quality volume (WQV)
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25 data could not be independently verified; and (2) the cost database is small and only contains between one and five examples of each BMP type.
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26 Life-Cycle Costs As stated earlier, life-cycle costs represent the sum total of design, construction, and O&M. Life-cycle costs are generally not well documented.
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27 From Caltrans (2004)
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28 infiltration basins, sand filters, bioretention areas, and vegetated swales. The life-cycle costs are presented as a series of equations where they are the sum of construction costs and design costs, which include design, permitting, erosion control, and contingency costs.
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29 life. Typical 10-year life-cycle cost estimates include capital costs (construction plus design)
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30 From King and Hagan (2011)
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31 NPDES MS4 permit. Within the Los Angeles River watershed, Caltrans operates and maintains 275.5 road miles and a number of park-and-ride facilities and maintenance stations.
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32 assets comprise only 1% of the watershed. The plan proposes a two-pronged approach including institutional BMPs (vehicle brake pad product replacement, enhancing street sweeping, education and outreach, catch basin cleaning, and downspout retrofits)
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33 considerations for 21 of the most commonly used runoff treatment BMPs available for highway applications. These are broadly grouped into infiltration, dispersion, biofiltration, wet pool, oil control, and phosphorus control BMPs.
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34 phosphorus, see Table 18) , in accordance with the Croton Watershed Phase II Phosphorus TMDL Implementation Plan.
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35 maintains MS4 permit coverage for the SHA roadway storm drain systems in nine Maryland MS4 Phase I counties and in two MS4 Phase II counties. The WIP only applies to these counties.
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