246-274-400  <<  246-274-405 >>   246-274-410

Location.

Tier 1, Tier 2, and Tier 3 greywater irrigation systems shall be designed and installed to meet the minimum horizontal setback requirements specified in Table I.
Table I
Minimum Horizontal Setbacks
 
From edge of subsurface irrigation components
From tank and other system components
Building foundations
 
 
 
 
 
Down-gradient1:
10 ft.
 
N/A
 
 
Up-gradient:
2 ft.
 
N/A
 
Property or easement line
2 ft.
 
2 ft.
 
Pressurized water supply line/public water main
10 ft.
 
10 ft.
 
Interceptor/
curtain drains/drainage ditches
 
 
 
 
 
Down-gradient:
30 ft.
 
N/A
 
 
Up-gradient:
10 ft.
 
N/A
 
In-ground swimming pool
10 ft.
 
5 ft.
 
Spring or surface water measured from the ordinary high-water mark2
100 ft.
 
50 ft.
 
Well or suction line
100 ft.
 
50 ft.
 
Public drinking water well
100 ft.
 
100 ft.
 
Public drinking water spring measured from the ordinary high-water mark
200 ft.
 
200 ft.
 
Decommissioned well (decommissioned in accordance with chapter 173-160 WAC)
10 ft.
 
N/A
 
Down-gradient cuts or banks with at least 5 ft. of original, undisturbed soil above a restrictive layer due to a structural or textural change
25 ft.
 
N/A
 
Down-gradient cuts or banks with less than 5 ft. of original, undisturbed soil above a restrictive layer due to a structural or textural change
50 ft.
 
N/A
 
On-site sewage system primary and reserve areas
10 ft.
 
N/A
 
1
The item is down-gradient when liquid will flow toward it upon encountering a water table or a restrictive layer. The item is up-gradient when liquid will flow away from it upon encountering a water table or restrictive layer.
2
If surface water is used as a public drinking water supply, the greywater system must be located outside of the required source water protection area.
[Statutory Authority: RCW 90.46.015. WSR 11-02-011, § 246-274-405, filed 12/28/10, effective 7/31/11.]
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