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
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