3. Engineer of Record - Primary Digester Repair & Lid Replacement ProjectREPORT TO: Mayor and City Council
TO: Bill Shaw, Public Works Director
FROM: Susie Turner, P.E., Water Resource Manager✓
SUBJECT: Engineer of Record — Primary Digester Repair and Lid Replacement
Project
MEETING DATE: November 7, 2011
BACKGROUND: The existing primary digester was constructed in 1984 as part of the plant's
Sludge Maintenance Facilities. The primary digester performs anaerobic digestion which reduces
and stabilizes biosolids. Gases are produced during the digestion process and used to produce
heat to maintain the temperature in the digesters. The gases are extremely corrosive and over
time can compromise the structural integrity of the tank, lid, and operational equipment.
In May of 1998 the Digester Rehabilitation Project was undertaken by the City to restore the
spalding interior concrete and a cracking dome lid with an elastomeric coating. At both the one
year and five year inspections, it was noted in inspection documents that all subsequent attempts
to repair the cracked and leaking lid had failed.
The current condition of the lid shows external fissures and cracking, and the foam insulation
cover is bulging in the cracked areas identified in the inspection documents. The mixing
equipment is in satisfactory working condition, but the current pumps used for mixing are no
longer manufactured and repair parts are hard to find and expensive. The unstable condition of
the lid creates safety hazardous for the WWTP Operation Staff. Routine inspections and
maintenance is required to be performed on the lid and external equipment, but has not been
completed due to the safety risk.
REQUIRED SERVICES: The services to be provided for this project include, but are not
necessarily limited to:
1. Inspect, analyze, and evaluate the structural and mechanical performance of the primary
digester (including the overflow box) including the following: lids, external roofing
material, walls, floors, internal piping, hardware and appurtenances, gas collection
piping, associate hardware and appurtenances, flame arrest/vacuum breaker, and mixing
equipment. Develop alternatives for repairs and replacements.
2. Inspect, analyze, and evaluate the status of existing concrete and metal protective coating
for the primary digester (including the overflow box). Develop alternatives for repairs
and replacements.
3. Prepare a comprehensive report of investigations, findings, alternatives, cost estimates,
and recommendations.
4. Prepare engineering designs, drawings, specifications and construction documents as
required for the repairs and replacements as deemed necessary by the City.
5. Administer bids for repairs and replacements, as required, including such items as
preparations of bid documents, pre -bid meetings, review of bids, and recommendation for
award.
6. Provide construction management for repair and replacement operations including, but
not necessarily limited to, a preconstruction meeting, inspection, testing service,
preparation of pay requests, and certifications of completed work.
7. Provide follow up inspection(s), as required, such as a two year warranty inspection.
In order to facilitate the completion of this project, the City advertised a request for Statements
of Qualification. On October 7, 2011, the City received three Statements of Qualification from
the following local and regional engineering firms: Stantec/Carver Engineering; HDR/ Morrison-
Maierle Engineering; and Advanced Engineering and Environmental Services, Inc. /CH2M Hill.
The selection committee reviewed the three responses and selected HDR/Morrison-Maierle
Engineering as the most qualified firm based on several technical and performance criteria.
ACTION REQUESTED: At Council Meeting November 7, 2011 — Motion to select the HDR/
Morrison-Maierle Engineering team as the Engineer of Record for the Primary Digester Repair
and Lid Replacement Project.
FISCAL EFFECTS: $150,000 is budgeted in the FY 2011/2012 Wastewater Treatment fund for
Primary Digester Lid Engineering.
ATIVES: As suggested by the City Council
.j Jane Howington
orks Director City Manager
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