UFC 4-171-05
1 January 2005
with change 25 October 2006
system designed for storage of the incremental increase in runoff from the overall
development. In such cases, the incremental runoff increase from the site will be verified
with the local water resources regulatory agency to ensure that it is within the
parameters of the regional pond design.
Figure 3-2
3-2.1.2.3
Underground or subterranean storm water
ARRTC VOQ,
Ft. McCoy, Wisconsin detention facilities, or ponding in parking areas, are measures
to be used only if space is not available for the construction of
surface storage facilities.
3-2.1.2.4
One of the sustainable design considerations
recommends that the storm water plan adopted for the site
results in a 25% decrease in the rate and quantity of storm
water runoff, if the existing impervious area of the site is greater than 50% of the site.
This would require on-site retention, not only detention, and may not be possible in all
cases.
3-2.1.2.5 Another recommended sustainable design measure is treatment systems for
storm water quality to remove 80% of the average annual post-development total
suspended solids and \ 40% /2/ of the average annual post-development total
phosphorus. This is to be implemented by instituting Best Management Practices
(BMPs) as outlined in EPA s "Guidance Specifying Management Measures for Sources
of Nonpoint Pollution in Coastal Waters" (EPA-840-B-92-002). The design
methodologies for determining percent removals are generally highly empirical and no
standard universal method has been adopted for this purpose. Therefore, the local
governing water resources regulatory agency or water resources department of the
Government installation directorate of public works will be consulted regarding
acceptable design methodologies for surface water quality treatment on developing
sites. These preferred local methodologies should be implemented for site design. On
some facilities, the site is not provided with a positive overland drainage outlet and
additional site area may be required for development of infiltration ponds sized to
accommodate the incremental increase in site runoff.
3-2.1.3
Temporary Measures
3-2.1.3.1 Temporary drainage measures will be implemented to provide for erosion and
sediment control according to the requirements of the National Pollutant Discharge
Elimination System (NPDES) program, as implemented and enforced by the responsible
state or local agencies. Do not assume that if less than 1 acre is being disturbed that
NPDES or some other permit is not required. Each state and many local agencies have
requirements for erosion and sediment control; these requirements should be obtained
and implemented either as part of the construction documents or as a requirement for
action by the construction contractor. The designer is typically tasked with preparing
preliminary permit paperwork for completion by the construction contractor.
3-2.1.3.2 Specific temporary measures preferred by the state or local water resources
regulatory agencies may need to be implemented to meet site-specific requirements.
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