Opportunities for U.S. Geological Survey Urban-Stormwater Investigations--National Pollution Discharge Elimination System Municipal Permitting Regulations, In Reply Refer To June 14, 1991 Mail-Stop 415 OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 91.08 Subject: PROGRAMS AND PLANS--Opportunities for U.S. Geological Survey Urban-Stormwater Investigations--National Pollution Discharge Elimination System Municipal Permitting Regulations, November 16, 1990 The U.S. Environmental Protection Agency (EPA) recently published a two-part municipal permitting regulation (Federal Register, November 16, 1990) which offers opportunities for U.S. Geological Survey (USGS) urban-stormwater investigations both locally and nationally. Attachment 1 is a map of cities (population > 100,000) subject to these regulations. [Note: Attachments 1-6 are being mailed under separate cover to offices that might actually become involved in these investigations.] USGS OPPORTUNITIES USGS districts may choose to develop urban hydrology cooperative projects with local governments to characterize the quality of water in storm sewers. Cities with a population greater than 100,000 (1990 census) are required to comply with the regulations by May 1993; those with populations greater than 250,000 must comply by November 1992. Attachments 2 and 3 summarize requirements for Part I and Part II of a city's National Pollution Discharge Elimination System (NPDES) permit application. Item III in Part II, Characterization Data, lists and describes in more detail the following four work elements that could involve USGS expertise: 1. For each city, data collection is required for 3 or more storm events at 5 to 10 gaging stations, including discharge data and water samples to analyze for about 140 chemical constituents. Data are to be collected from small catchments (1/2 sq. mi. or less) with a homogeneous land use. Based on work published in Water- Supply Paper (WSP) 2363, "Techniques for estimation of storm-runoff loads, volumes, and selected constituent concentrations in urban watersheds in the United States," by Nancy Driver and Gary Tasker, the Water Resources Division (WRD) recommends collection of samples for at least six storm events per site to achieve sound statistical analyses. A bibliography of representative USGS reports in urban stormwater hydrology is given in Attachment 4. Many of these studies were completed as part of the Nationwide Urban Runoff Program (NURP) in cooperation with the EPA. 2. Annual and storm load estimates are to be made for a set of 12 parameters of the 140 to be measured for individual storms. The 12 are: biochemical oxygen demand (BOD), chemical oxygen demand, total suspended solids, dissolved solids, total nitrogen, total ammonia plus organic nitrogen, total phosphorus, dissolved phosphorus, cadmium, copper, lead, and zinc. Estimates of annual loads can be made for each of these except BOD (an equation for BOD is not available) using the regional equations, validated with locally collected data, published in (WSP) 2363. An extension of the computational method has been developed by Tim Cohn, Branch of Systems Analysis, Gary Tasker, National Research Program, and Anne Hoos, Tennessee District, for adjusting regional equations with local data. The extension procedure is available on USGS PR1ME computers and can be obtained through Gary Tasker, NRP, Reston, Virginia. 3. NPDES application also requires that load estimates (for the same 12 parameters as above) be made for the entire urban area of each city. Constituent-load estimates can be efficiently made using the WSP 2363 procedures linked to a Geographic Information System. Application of this approach is being tested in the Dallas-Fort Worth area, where the Texas District has an urban hydrology stormwater project involving a 30-gage NPDES network, in cooperation with the North Central Texas Council of Governments. Attachment 5 is the project proposal for the Dallas-Fort Worth urban-hydrology project. 4. EPA regulations require continued "monitoring" at the gaging sites during the 5-year term (following NPDES permit approval) of the NPDES permit to evaluate performance of a required stormwater-management program. This required element affords an opportunity to extend and improve equations and estimates made under Part II of the NPDES permit application. Additionally, deterministic modeling could be evaluated during the monitoring term. Additional references that are available for WRD districts preparing proposals include: Berg, E. L., 1982, Handbook for Sampling and Sample Preservation of Water and Wastewater, U.S. Environmental Protection Agency, 414 p. Tai, D., Jennings, M. E., White, K. D., and Garcia, L. A., 1991, Evaluation of a Modified Automatic Sampler for the Collection of Water Samples Containing Trace Organic Compounds or Suspended Sediment, U.S. Geological Survey Open-File Report (in process), 75 p. Witkowski, P. J., Smith, J. A., Fusillo, T. V., 1982, Manmade Organic Compounds in the Surface Waters of the United States--A Review of Current Understanding, U.S. Geological Survey Circular 1007, 92 p. Witkowski, P. J., Smith, J. A., Fusillo, T. V., and Chiou, C. T.,1987, A Review of Surface-Water Sediment Fractions and Their Interactions With Persistent Manmade Organic Compounds, U.S.Geological Survey Circular 993, 39 p. The four areas of potential Geological Survey involvement can be shaped into a sound investigative project. In addition, there may be an opportunity for new research to improve upon the national and regional equations of WSP 2363 by including local data to develop new locally applicable models to estimate urban-stormwater loads. ADVANCING THE NATIONAL PERSPECTIVE Results from the previous work under the NURP provide an important foundation for involvement with states in the NPDES process. The NURP resulted in both the Driver and Tasker equations and a USGS- assembled national stormwater-hydrology data base. Specific site selection and storm-sampling criteria were used to produce the data base from which the equations were derived. Involvement of WRD districts in the NPDES urban-stormwater investigations can extend USGS national data bases in urban-stormwater hydrology. To improve upon the NURP data base, several factors must be considered: 1. Careful site selection is important. Most basins monitored should fall within the characteristics of the NURP basins for each region, especially if a project will use the Driver and Tasker equations for load estimation. 2. Consider selecting sites in locations intended for Best Management Practice (BMP) modification under the permit monitoring effort. Monitoring BMP-effected basins is necessary for NPDES permit evaluation. 3. Storm sampling should follow the same criteria as used to define storms for the NURP data base (see WSP 2363). Thus, samples should be collected over the entire hydrograph, not just the first 3 hours. 4. Collection of snowmelt samples alone may not be adequate in determining mean annual loads, especially in areas where frozen precipitation accounts for less than half the annual precipitation volume. LABORATORY CONSIDERATIONS In development of project proposals, WRD districts should include identification of the analytical methods they plan to use. Methodologies should be approved or accepted by EPA prior to initiation of the study. Approval can be negotiated with the EPA Regional Office. A listing of USGS lab methods and capabilities is attached (Attachment 6) and can be used to describe available methods to cooperators and EPA. Project proposals further should include a description of adequate quality-assurance procedures. These procedures should include: protocols for sampler cleaning, sample collection, and processing of blanks, spikes, and splits. Protocols will be developed by the National Water Quality Laboratory (NWQL); Mark Sandstrom will coordinate. WRD districts should contact NWQL (Doug Maingold, Merle Shockey, or Rich Hawkinson) as soon as new projects emerge to develop a priority commitment with NWQL, especially if a project will require analytical results within a predetermined timeframe. If NWQL capacity is exceeded, use of contract laboratories may be an option. To assist in interlaboratory bias assessment when analyses are provided by multiple laboratories, it is recommended that quality-assurance procedures include at least 5 percent split-sample analyses by participating laboratories. NPDES permit applications require characterization and load estimation for volatile organic compounds (VOC). Presently, the Hydrologic Instrumentation Facility is evaluating adaptations to automatic samplers that will allow collection of VOCs. Contact Doreen Tai for status of sampler modifications. OFFICE SUPPORT WRD plans to fully support WRD district efforts in NPDES urban- stormwater investigations, as was done with NURP urban-stormwater investigations during 1978-1983. A coordination team composed of representatives from the Office of Surface Water, Office of Water Quality, NRP, and NWQL is overseeing the NPDES urban hydrology study efforts. An initial workshop was held on February 13, 1991, in Nashville, Tennessee. It is suggested that Districts contact city government officials as soon as possible (see Dallas-Fort Worth study work element/time lines) in public works and environmental offices if USGS involvement is desired. For studies to begin in fiscal year 1992, cities with populations greater than 250,000 should be contacted as soon as possible. If interest is sufficient, a national workshop on NPDES urban hydrology investigations may be held in Dallas in early July 1991. Districts desiring additional information regarding the EPA regulations or future workshops may contact Marshall Jennings, Urban Hydrology Studies Coordinator for the Office of Surface Water (FTS 873-3068) Austin, Texas, or Timothy Miller, Office of Water Quality (FTS 959-6868), Reston, Virginia. David A. Rickert, Chief Charles W. Boning, Chief Office of Water Quality Office of Surface Water DISTRIBUTION: A, B, FO, PO