FLOOD09481

• County: Statewide
• Community: State
• Stream Name: All
• Basin: Statewide
• Title: Practices in Detention of Urban Stormwater Runoff
• Date: 1/1/1974
• Prepared For: American Public Works Association
• Prepared By: American Public Works Association
• Floodplain - Doc Type: Educational/Technical/Reference Information

runoff flows from nearby upstream
communities, flood-prone areas must depend
upon upstream communities to implement
programs of flood control which may provide
little direct local benefit to these neighboring
communities.
18. The removal of connections of roof
drains to sanitary or combined sewers is a
method commonly used to reduce the
hydraulic loading on sewers and sewage
treatment plants. A successful program of
removal of roof drain connections can provide
an effective and economical means of
reducing local flooding and pollution
problems if satisfactory means are employed
on~ite to handle resulting roof drainage.
19. The use of on-site detention of
storm water is not a cure-all solution.
Although many studies favor the use of
detention to reduce runoff flow rates to levels
capable of being handled by existing sewers,
other studies have favored the construction of
new sewers (relief sewers) sufficient to handle
the large urban runoff without causing
flooding, The evaluation of the alternatives
should be based upon economics and
anticipated problems of maintenance and
operation. If relief sewers are proposed,
careful investigations should be made of the
possibility of aggravating downstream
flooding.
20. On-site detention of runoff may be
effective in reducing storm water pollution -
by preventing overflows of combined sewers
and reducing flow rates in sewers to levels at
which treatment of urban runoff is feasible.
21. Because on-site detention of runoff is
a relatively new concept, further studies of all
aspects of this method of managing runoff are
needed to improve its effectiveness and to
develop new ways to achieve stormwater
management goalS from both technological
and administrative viewpoints.
22. Flood plain zoning was found to be
an important and effective counterpart to
on-site detention of runoff for the
development of comprehensive stormwater
management programs.

CONCLUSIONS
The study of the use of on-site
stormwater detention techniques and their
advantages and disadvantages have led to the
following conclusions:
I. On~ite detention of urban runoff is a
viable part of a solution to runoff problems in
storm water management, offering both
economy and the opportunity to put
stormwater to use rather than treat it as a
waste material to be disposed of promptly.
2. Techniques involving on-site
detention of stormwater are not always
applicable in solving all problems encountered
in controlling urban runoff; but, in many
cases, on~ite detention may be an important
part of the best solution available.
3. Future research concerning on-site
detention of stormwater will aid in improving
the effectiveness and adaptability of the
method, Especially important will be
mutually acceptable and reliable methods of
providing and delegating needed maintenance
and operation duties.
4. Dissemination of information on the
methods and benefits of on-site detention will
probably result in its increased usage. At
present, people in many places are unfamiliar
with the concepts and techniques even though
attitudes on detention storage are generally
favorable.
5. Legal aspects of stormwater
detention are not well-defined, and many
questions need to be answered to facilitate its
use.
6. Financing of stormwater detention
facilities can be by several methods, especially
in multiple-purpose projects.
7. The short-tenn effectiveness of
on-site detention for controlling flooding,
pollution, soil erosion and siltation problems
has been documented; long.tenn effectiveness
seems probable, but has yet to be
substantiated for different methods of
application.
8. Design practices for on-site
stormwater detention facilities are
complicated by local political conditions and

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