The District requests Bids for the Cleaning and Inspection of two parallel 42-inch corrugated metal pipe outfalls, each about 300 ft long. The outfalls have not been cleaned regularly and an unconfirmed amount of fine sediment has deposited within the two pipes. a. This task will consist of the mobilization of the CONTRACTOR's
equipment, project familiarization, pre-inspection coordination, and
project kick-off. Mobilization may include:
i. Project site kick-off meeting / site visit
ii. Project familiarization and project management, including the submittal of a
workplan describing ingress/egress to the work site and proposed work a. This task will consist of the mobilization of the CONTRACTOR's
equipment, project familiarization, pre-inspection coordination, and
project kick-off. Mobilization may include:
i. Project site kick-off meeting / site visit
ii. Project familiarization and project management, including the submittal of a
workplan describing ingress/egress to the work site and proposed work Dredging and Testing of Deposited Sediment
a. CONTRACTOR shall isolate flow to work area, as needed per site
conditions, to minimize flows and impacts to aquatic life. This may be
done by insertion of an inflatable plug into the 60-inch culvert on NE
223rd, or by an approved equivalent method. Work shall be conducted
during permitted work windows and in allowable weather conditions.
b. Prior to inspection and cleaning of Gate Tower outfalls, CONTRACTOR
shall dredge upstream and downstream deposited sediment in order to
remove any obstructions to culvert gravity flow, as needed per site
conditions. The objective of dredging is solely to provide access to the
pipes for inspection in accordance with PACP standards and provide a
collection area for sediments residing in the pipe. If CONTRACTOR
determines that removal of the trash rack and upstream dredging are not
necessary to perform the required inspection, and access is otherwise
not required, the installation of site access and staging on the upstream
(western) side of the cross levee will not be required and this optional
line item will not be executed.
c. Leachate from dredged material will be sampled and tested at a lab subcontracted through DISTRICT to identify appropriate waste method.
d. CONTRACTOR shall handle and dispose of waste based on outcome of
leachate testing, per permit requirements (see Oregon Department of
State Lands Programmatic Permit 62146-RF Modified).
e. In accordance with DEQ 401 General Construction Conditions,
CONTRACTOR shall monitor turbidity and implement appropriate Best
Management Practices (BMPs) to minimize turbidity during in-water
work.
3. Inspection and cleaning of two 42-inch Gate Tower outfalls.
a. Following pre-cleaning work upstream and downstream of outfalls,
CONTRACTOR shall isolate and clean each outfall.
i. No upstream flow shall be entering the pipe and no standing water shall be
present in the pipe during inspections.
ii. Isolate one culvert at a time by installing inflatable plug or appropriate
equivalent. No bypass required as any flows will divert to non-isolated
culvert.
iii. Clean culverts and remove sediment using Vactor or appropriate equivalent.
Sediment not removed directly from the culverts may be captured and
removed at the downstream cofferdam. CONTRACTOR shall coordinate with
DISTRICT on most appropriate method to remove, dry, and dispose of
sediment.
iv. CONTRACTOR shall handle and dispose of sediment based on outcome of
leachate testing, per permit requirements Question Deadline 02/12/2024 at 3:00 PM
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