Page 49 - Puret Sound Energy Hand Book 1218

Chapter 4

Trench The following requirements for the trench must be met before power conduits/cables
excavating will be installed.
requirements • When you trench in a right-of-way on PSE’s behalf, the governing jurisdictions
issue public roadway use permits to PSE.
• For trench work provided by you within a public right-of-way or a PSE easement,
PSE requires that you use a Washington State licensed and bonded contractor
and complete and sign a PSE trenching agreement form.
• Trench work within a public right-of-way must meet the erosion and sediment
control requirements of the local jurisdiction.
NOTE: Acquiring permits for excavation-related activity can take up to a month
or longer depending on the amount of material being excavated, location of the
excavation, and the jurisdiction issuing the permit. To avoid schedule delays, contact
your PSE Project Manager for an estimated time frame to acquiring your permits.
• Provide a signed Excavation Requirements & Final Grade Certification document
supplied by your Project Manager or PSE Representative.
• The trench shall be excavated according to the trench detail and PSE’s work
sketch.
• The trench shall be straight and the trench bottom shall be smooth, level, and
free from obstructions, sharp objects, or rocks larger than 1/2 inch in diameter.
• Excavated or loose material shall be placed at least 2 feet from the field edge of
the trench.
• Water shall be removed by pumping or draining following the erosion and
sediment control requirements of the local jurisdiction.
NOTE: Trenches or vault excavations that are 4-feet-deep or greater require special
sloping. Contact your PSE Project Manager for these requirements.

Trench and PSE will not energize its facilities until backfill is completed.
backfill When PSE primary cables are directly buried, or installed in PSE-provided gray
requirements DB120 grade conduit, you are responsible for the following:
for primary
electric line • Providing a minimum 3-inch bedding layer of sand, 5/8-inch minus, or clean
extension backfill (with rocks or solid material no larger than 5/8 inch in diameter and no
trenches (no sharp objects) placed below cables/conduits.
PSE gas) • A 12-inch layer of the same shading material above the directly buried cables/
conduits.
• If native backfill is completely free of foreign objects and rocks in excess of
8 inches in diameter, shading with sand, 5/8-inch minus, or clean backfill can be
reduced to 6 inches.
• The remaining trench shall be backfilled with soil that is free of rocks larger than
10 inches in diameter and foreign objects.
When PSE primary cables are installed in gray Schedule 40 grade or better conduit,
you are responsible for the following:
• Backfilling the trench with soil that is free of foreign objects and rocks larger than
10 inches in diameter. Bedding and shading of the conduit with sand, 5/8-inch
minus, or clean backfill is not required.

Electric Service Handbook 2017 — Single-Family Residential Projects 40