TM 5820-4/AFM 885, Chap 4
CHAPTER 1
INTRODUCTION
downstream conditions leading to unfavorable
public relations, costly litigations, or damage
manual is to discuss normal requirements for de-
claims. Any agreements needed to obtain drain-
sign of surface and subsurface drainage systems
age easements and/or avoid interference with water
for military construction other than airfields and
rights will be determined at the time of design
heliports at Army, Air Force and similar instal-
and consummated prior to initiation of construc-
lations. Sound engineering practice should be fol-
tion. Possible adverse effects on water quality due
lowed when unusual or special requirements not
to disposal of drainage in waterways involved in
covered by these instructions are encountered.
water-supply systems will be evaluated.
12. General investigations. An on-site inves-
13. Environmental considerations.
tigation of the system site and tributary area is
a prerequisite for study of drainage requirements.
ficial or adverse environmental impacts affecting
Information regarding capacity, elevations, and
water, land, ecology, and socio-economic consid-
condition of existing drains will be obtained. To-
erations. Effects on surrounding land and vege-
pography, size and shape of drainage area, and
tation may cause changes in various conditions in
extent and type of development; profiles, cross
the existing environment, such as surface water
sections, and roughness data on pertinent exist-
quantity and quality, groundwater levels and
ing streams and watercourses; and location of pos-
quality, drainage areas, animal and aquatic life,
sible ponding areas will be determined. Thorough
and land use. Environmental attributes related
knowledge of climatic conditions and precipitation
to water could include such items as erosion, flood
characteristics is essential. Adequate information
potential, flow variations, biochemical oxygen de-
regarding soil conditions, including types, perme-
mand, content of dissolved solids, nutrients and
ability on perviousness, vegetative cover, depth
coliform organisms. These are among many pos-
to and movement of subsurface water, and depth
sible attributes to be considered in evaluating en-
of frost will be secured. outfall and downstream
vironmental impacts, both beneficial and adverse,
flow conditions, including high-water occurrences
including effects on surface water and ground-
and frequencies, also must be determined. Effect
water.
of base drainage construction on local interests'
b. Federal agencies shall initiate measures to
facilities and local requirements that will affect
direct their policies, plans, and programs so as to
the design of the drainage works will be evalu-
meet national environmental goals and stand-
ated. Where diversion of runoff is proposed, par-
ards.
ticular effort will be made to avoid resultant
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