2.0 SYSTEM DESIGN
© Presby Environmental, Inc., Design & Installation Manual, September 2020 Edition
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Illustration of by-pass venting:
2.8 Site Selection
Determining Site Suitability
Refer to DHSS regulations and local rules regarding site suitability requirements.
Topographic Position Requirement
AES systems shall not be located where surface or ground waters will converge, causing surface water flow to
become concentrated or restricted within the soil absorption field. The system shall be located in an area that does
not concentrate water, both surface and subsurface. If allowed by state and local authorities, altering the terrain
upslope of a system may alleviate this requirement if the waters are sufficiently altered to redirect flows away
from the field.
•
Locate systems on convex, hill, slope or level locations. Avoid swales, low areas, or toe-of-slope areas that
may not provide sufficient drainage away from the system.
•
No onsite system may be located on concave slopes that concentrate surface or ground water flows
unless up-slope terrain is sufficiently altered or interceptor drains are used to redirect water away from
the system.
•
Systems should not be located where lawn irrigation, roof drains, or natural flows increase water loading
to the soils around the system.
Divert surface water away from the system.
•
Interceptor drains, if used, must be upslope of the AES system and a minimum of 10 ft away from all AES
pipe.
•
Systems should not be located where structures such as curbs, walls or foundations might adversely
restrict the soil’s ability to transport water
away from the system.
