the written change order or the fully executed OWNER Purchase Order shall control over the
terms of the Proposals
ARTICLE 2— WORK TO BE PERFORMED
Except as otherwise provided in this contract, CONTRACTOR shall furnish all services,
equipment, and materials and shall perform all operations necessary and required to carry out and
perform in accordance with the terms and conditions of the contract the work described.
DESCRIPTION OF WORK:
This PROJECT consists of replacing the existing diaphragm inside the gas tank along with
modifications to the method of attachment of the diaphragm to the tank wall.
The following is a general summary of the expected work to be performed and sequence to
follow. The CONFRACTOR is not bound by these methods and may use alternate procedures
upon approval by the wastewater engineer. Additional work or steps may be needed that are
not reflected in the following description for the complete installation of the new diaphragm.
Video inside layout of piston and diaphragm such that all components (sections of piston
wall, concrete block ballast layout...) can be reinstalled to exact layout as existing. Remove
existing cables that are used to raise and lower the piston. Remove section of piston walls
(bolted) noting location and order of removed sections. Stack wall sections inside tank at
base. Provide the necessary rigging to remove each section of the piston wall.
Remove upper and lower rings that connect the diaphragm to the tank and base of the
piston. New gasket material and bolts/nets shall be installed upon reconnection of rings and
piton wall sections.
Remove existing diaphragm. Cut hole in top of tank of sufficient size to remove existing
diaphragm from tank. A crane will be needed to facilitate this operation. The existing 24-
inch diameter hatches are likely too small to remove the old and reinstall the new
diaphragm.
Remove upper seal connection bracket and invert such that diaphragm can be bolted to the
bracket from the air side of the tank interior. CONTRACTOR to determine means and
methods to remove existing bracket, reuse or install new bracket with angle iron facing up.
Connect the new diaphragm to upper and lower seal brackets using new bolts, nuts, washers,
bracket bars, and gasket material as necessary to securely attached the top and bottom of
new diaphragm.
Install all 8 sections of piston wall.
Remove old and install new cables that attached to piston and counter weights to assist with
lowering and raising of piston.
Touchup areas where needed with new coatings specified by OWNER.
Operate new gas tank with large air compressor to check operation and determine any
adjustments that may be needed.
Perform leak tests
Purge gas holder with nitrogen gas. Keep system filled with nitrogen gas until startup using
digester gas.
The CONTRACTOR is expected to use high quality construction materials for this work
including all new stainless steel bolts and nuts wherever removed.
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