© Presby Environmental, Inc., Maine Design & Installation Manual, June 2019 Edition -21-
32.8 By-Pass Venting
33.0 Site Selection
33.1 Determining Site Suitability
Refer to Maine Rules regarding site suitability requirements.
33.2 Topography
Locate systems on convex, hill, slope or level locations that do not concentrate surface flows. Avoid swales, low
areas, or toe-of-slope areas that may not provide sufficient drainage away from the system.
33.3 Surface Water Diversions
Surface water runoff must be diverted away from the system. Diversions must be provided up-slope of the system
and designed to avoid ponding. Systems must not be located in areas where surface or groundwater flows are
concentrated.
33.4 Containment
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.
33.5 Hydraulic loading
Systems should not be located where lawn irrigation, roof drains, or natural flows increase water loading to the soils
around the system.
33.6 Access
Systems should be located to allow access for septic tank maintenance and to at least one end of all pipe rows.
Planning for future access will facilitate rejuvenation in the unlikely event the system malfunctions.
33.7 Rocky or Wooded Areas
Avoid locating systems in rocky or wooded areas that require additional site work, since this may alter the soil’s ability
to accept water. No trees or shrubs should be located within 10 ft. of the system to prevent root infiltration.
SLOPE
SLO
PE
BY-PA
SS V
ENT
ATTACH BY-PASS VENT TO
PUMP CHAMBER OR UNUSED
OPENING IN SEPTIC TANK
WHEN USING BY-PASS VENTING THE ROOF VENT
REPLACES THE "HIGH" VENT AND PUMP CHAMBER
VENT (IF REQ'D). THE OPENING OF ROOF VENT MUST
BE AT LEAST 10 FT. ABOVE OPENING OF LOW VENT
D-BOX
FINISH GRADE
SEPTIC TANK WITH
SANITARY TEE BAFFLES
PUMP
CHAMBER
BY-PASS VENTING REPLACES BOTH
THE HIGH VENT AND PUMP CHAMBER
VENT (IF REQUIRED)
E
L
IM
IN
AT
E
D
LOW VENT IS AIR
INTAKE
E
N
I
L
P
M
U
P
TO D-BOX
NO EFFLUENT
FILTER
ADD PUMP CHAMBER BY-PASS VENT IF EFFLUENT
FILTER IS USED ON SEPTIC TANK OUTLET BAFFLE
A
A
PUMP CHAMBER BY-PASS
VENT HIGHER THAN INLET
& ABOVE TOP OF TANK
VIEW A-A
(ROTATED 90°)
SEPTIC TANK
OPTIONAL CONFIGURATION
(IF EFFLUENT FILTER USED)
SEPTIC TANK
PUMP BOX
10' MIN
3'
P
M
U
P
LIN
E
PRESBY FIELD
NOTES:
1. NOT TO BE USED WITH GRAVITY SYSTEMS.
2. INVERT OF PIPE EXITING D-BOX MUST BE 2"
MINIMUM ABOVE D-BOX.
3. USE 4" SCH. 40 PVC OR EQUAL FOR BY-PASS
VENTING.
4. GLUE ALL PVC JOINTS OR EQUAL.