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

aspects and opinions were of prime interest.
The study focused upon the prevention and
mitigation of problems associated with
providing and operating satisfactory
stormwater drainage systems and controlling
local flooding, water pollution, soil erosion,
and siltation resulting from local soil erosion.
A secondary purpose o(the study was to
evaluate on-site detention of runoff as a viable
alternative to other storrnwater management
methods used, or planned, by urban
communities for controlling runoff. Another
area of interest and investigation was the
capture and use of urban stormwater runoff'
for water supply, recreation and enhancement
of urban land areas.

The study included investigations of:

I. temporary ponding on ground surfaces;
2. temporary ponding on paved areas;
3, temporary ponding on roofs of buildings;
4. storage in permanent ponds having
provision for variable depth;
5. treatment of ground water surfaces to
absorb and/or detain water;
6. routing of runoff to infiltration pits to
both recharge groundwater supplies and
reduce total flows to drainage systems;
7. collection of stormwater for
supplementary water supplies; and
8. reducing stormwater runoff rates to
reduce soil erosion and siltation.

Conduct of the Study: Inputs to the stocly
were provided by more than 100 participants
serving either as symposium participants,
consultants, or members of the study team.
The project activities included the following:

I. conducting three symposia to discuss
on-site detention of runoff (held in
Chicago, Denver and Fairfax County,
Virginia) ;
2. literature search of articles on the subject
of stormwater management, focusing
upon on-site detention of stormwater
runoff;
3. survey of public agencies and engineering
firms;
4. study of applications of on-site detention
of runoff;

5. study of underground storage of runoff;
6. study of new ideas for on-site detention
of stormwater runoff;
7. study of legislation and legal aspects of
detention of stormwater;
8. examination of factors associated with
maintenance, operation, costs, financing,
economics, engineering effectiveness,
design criteria, and implementation
impediments;
9, study of unconventional methods to
detain runoff;
10. study of removal of roof drains from
sanitary sewers;. and
II. study of the use of impervious
membranes to trap and collect runoff for
beneficial use.

FINDINGS
The gene-ral findings of this study,
expanded upon in other sections of this
report, include the following:
I. On-site detention of runoff can be an
effective, economical method of stormwater
management.
2. Besides controlling local flooding and
pollution from combined sewer overflows,
on-site detention techniques can be used to
capture runoff for supplementing water
supplies or for multiple-purpose use. It is also
a useful technique for erosion and siltation
con trol.
3. Use of on-site detention techniques
is relatively widespread and has been in
general use for at least 15 years. About 100
respondents to a questionnaire survey of
approximately 500 randomly-selected local
public agencies in the United States and
Canada reported the existence of about 1,400
facilities.
4. The principal disadvantages to the
use of on-site detention in runoff control are
the problems of maintenance and operation
of facilities. The problems are twofold - the
actual performance' of the maintenance and
operation, and the delegation of responsibility
for this work either to local public agencies or
land owners.
5, Many of the key personnel of local
jurisdictions were found to have little, if any,

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