2013 Water System Plan, Volume II - Seattle City Clerk's Office - City ...

Chapter 18 Plan Review
18.4.9.1 Build-over Review
The SPU plan reviewer must confirm:
18.4.9.2 Build-over Process
1. That the casing pipe inside diameter is larger than the outside
diameter of the bell of the sewer/storm main. The proposed
pipe must be sized to convey the design flows for the entire
basin under full “build-out” for the corresponding zoning.
2. The minimum steel casing thickness shall be ¼-inch. External
loading may require thicker and stronger casing. Casing shall
extend at least 5 feet beyond the edge of building foundation
1:1 influence line. Steel casing pipe is preferred, although
ductile iron pipe may be used in certain circumstances. Use of
any HDPE, PVC or any other plastic pipe is not allowed.
3. The sewer/storm main must be restrained joint within the
casing pipe.
4. No private side sewer or storm connections are allowed within
the casing pipe.
5. Casing spacers must be stainless steel to maintain line and
grade of pipe and to prevent floatation. Place at bell ends with
9 feet maximum spacing.
6. An unobstructed 10 x 20 foot minimum access area
(unobstructed) located on both sides of the building is
preferred. If that is not feasible, SPU may allow one access area
for future trenchless maintenance or repair. Larger diameter
pipes may require larger access areas and easement widths.
7. A removable end cap or a 1 foot deep concrete plug must be
included in order to seal the space between the casing the
main.
8. Additional MHs may be required, as necessary.
9. The Seattle City Council must approve any easement legislation
required prior to issuing the permit for construction.
10. Final as built plans must be filed in the SPU Records Vault.
The following are the steps for a developer to request a build-over:
1. Real Property Services (RPS) circulates the owner’s proposal to the SPU Plan Reviewer
and to Field Operations for preliminary evaluation.
Participants discuss proposal in a scheduled build-over meeting
a. If necessary, RPS coordinates a meeting with the property owner or their agent.
b. RPS, after consulting with Plan Review and FOM, will advise if SPU can grant
consent.
The Plan Reviewer conducts preliminary review and sends recommendations to RPS.
SPU Design Standards and Guidelines 18-15