3.07
Changes in direction of flow or sewer centerline within a manhole shall be made by
forming the flow channel along a smooth curve with as long of a radius as the inside of
the manhole will allow.
Bench shall slope toward invert as shown on the Rehabilitation of Existing Manhole detal|
on Drawing DO2 for proper drainage to the invert channel.
Benches shall be built up to a height as shown on the Rehabilitation of Existing Manhole
detail on Drawing DO2 for the entering and exiting pipes and shall be given a uniform
wood float finish.
Where possible, anon-shrink grout fillet shall be installed around pipe penetrations above
the bench.
DROP BOWL ASSEMBLY:
Drop pipe and bowl shall be connected to the pipe(s) enteing a manhole using
manufactured couplings or fittings.
Schedule 40 PVC pipe shall be connected using industry-grade solvent cement.
Drop pipe shall be secured to the inside of manhole using steel straps or struts. Straos
shall have aminimum width of 1/2 inch and a minimum thickness of 0.03 inch.
Tee and bottom elbow shall be firmly secured by straos. Intermediate straps shall be
spaced at aminimum of 5 feet. Straps shall be esoxy-anchored to manhole using 1/4-inch
anchors (two per strap). Anchor shall be enbedded into mortar a minimum of 3 inches.
Bottom elbow shall be seated on bench for support.
If amanufactured drop bow! product is used, drop assembly shall be sized and installed in
strict accordance with the manufacturer’ s installation instructions and guidelines.
INSPECTION, TESTING, AND ACCEPTANCE:
Contractor shall have appropriate equipment and OSHA training to dlow the Owner
and/or Engineer to enter and inspect the manholes during rehabilitation. If any defects are
observed, products shall be repaired or reolaced at no cost to the Owner using a method
acceptable to the manufacturer aid Owner and/or Engineer.
Vacuum testing in accordance with ASTM C1244 shall be required on one randomly-
selected manhole for each group of five manholes rehabilitated with internal liners.
Contractor shall perform vacuum testing with appropriate test equipment in the presence
of an inspector. Any manholes failing this test shall be reworked as necessary and
retested at no additional cost to the Owner. All verification and vacuum testing shall be at
no cost to the Owner and shall be paid for by the manufacturer or the Contractor.
Holiday detection testing in accordance with ASTM D4787 shall be required on one
randomly-selected manhole for each group of five manholes rehabilitated with internal
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