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

C. Mitigation of Damaged Water Mains
When vibration monitoring is required, SPU will perform a pre- and post-construction
acoustic leak survey of the existing water lines near the construction activities. If
damage or leaking increases and is determined to be caused by the construction
activities, the RE will send a written request to the contractor to restore damaged or
destroyed property to its original condition. The contractor, not the owner or City of
Seattle, must pay for and the repair or replacement of the pipe according to City
Standard Specifications.
5.10.2 Removal and Abandonment of Existing Water
Mains and Appurtenances
The following are SPU standards:
1. Where required for water main projects, removal of existing water mains and
appurtenances must meet the requirements of Standard Specification 2-02.3(7)B.
2. All ends of abandoned water mains must be plugged. Pipes 12 inches or larger in
diameter must be abandoned and filled in accordance with Standard Specification 2-
02.3(5).
3. Water pipes designated on project drawings to be abandoned and filled must be
filled with pumpable, flowable cement slurry that completely fills the pipe (Standard
Specification 9-05.15).
4. After the record drawings (as-builts) have been incorporated into GIS, the design
engineer must check that the abandoned pipe is properly shown.
5.10.2.1 Considerations for Disposal of Hazardous Materials
The design and specifications of projects that remove or abandon water facilities must identify
pipes that are known to have or may have hazardous materials. The contractor needs this
information to calculate the costs for special handling and disposal. The most commonly found
hazardous materials in SPU’s water system and considerations for their mitigation or removal
are described in Table 5-12.
Table 5-12 Hazardous Materials associated with SPU Water System
Material Prevalence in System Mitigation/Removal
Asbestos Cement Pipe
Lead Joints
Coal Tar-Lined and
Coated Steel Pipe
Commonly used in water mains installed in
1940s and 50s. Uncommon now
Almost all joints in older cast iron pipe have
lead seals. Most of SPU’s distribution system
is cast iron w/ lead joints and can be expected
to have decades useful service if not physically
disturbed
SPU has coal tar coatings and or linings in the
Cedar River Pipeline System as well as a few
other steel pipes
Avoid removal and abandon in-place
where possible. If removal is
necessary, containment and filtration
requirements must follow OSHA and
WISHA
Recycled by crews for other crew
work
If removed, disposal to a licensed
hazardous waste landfill. Working and
handling of coal tar materials must
follow OSHA and WISHA standards.
5-66 SPU Design Standards and Guidelines