Industry Day.pptx

Industry Day 2nd Crest Raise at the Sediment Retention Structure (SRS) on the Toutle River Controlled by: U.S. Army Corps of Engineers Controlled by: CENWP-PPPD CUI Category: General Critical Infrastructure Info Limited Dissemination Control: FEDCON POC: Karl Ahlen 503-808-4757

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Agenda Project Location Overall Plan Schedule Constraints

Project Location Project Location

Overall Plan

Area affected by the in- water work window

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Schedule Advertise Mid June Bid Opening Mid July Award End of September Construction start (in water work window) 1 July 4 2023 Construction completion (In water work window) 4 Oct 2023

(In water work refers to any work that involve working in the water, these activities would include but not limited to diversion channel construction, placement of RCC, preparing existing crest surface to the project and other activities. It does not include the set up that would be needed outside the channel such as setting the batch plant, office area and doing test areas for the RCC placement.)

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Constraints In work window July 1 through Oct 4th Work site, it will be tight Decommissioning the outlet works will involve work in confined quarters.

Quantities 33,000 CY of Roller compacted concrete 2,100 CY of rocks excavation

Crest raise (2023)

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Spillway raise project 2023 5/25/2022

Spillway (2023)

Crest raised 10-feet above existing (33,000 CY)

Plunge Pool Excavation (2,000 CY)

Low flow Notch at 10% slope Spillway flows continuously

Spillway crest: 959 ft-NGVD29 Low flow notch at 955.5 ft

Maximum discharge capacity: OBM of 228,000 cfs

Berms 3.5 feet high, 8 feet wide

Apron with vertical drain holes

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Per 100% DDR No. 16 “Sediment Retention Structure 7-foot Spillway Raise” (2013) when all flow passed through the SRS outlet works, the sediment trapping efficiency of the SRS was approximately 92%. When the outlet works pipes were buried and closed in 1998, sediment trapping efficiency of the SRS dropped to approximately 31% and more sediment began to deposit in the Cowlitz River.

The spillway was crest raised by seven feet in 2012 to an elevation of 947 ft-NGVD29 (950 ft-NAVD88) as the first phase of a three-phased spillway raise intended to ultimately reach 970 ft-NGVD29 (973 ft-NAVD88). The seven-foot raise was designed to handle all water, sediment, and debris loadings. The spillway raise was located at the anticipated final location of the ultimate potential 30-foot raise. To maintain the same 7% slope as in the existing spillway channel, the position of the new crest was located be approximately 430 feet upstream (east) of the original crest. The new spillway section was constructed of RCC placed in approximately one-foot lifts. The placement of RCC was done in such a way that reinforcement was not be required. The crest was essentially built in three levels with the lower two levels intended to pass fish within the design juvenile range of low and high design flow rates.

low flow channel (2023)

Low flow Notch at 10% slope

Spillway Notch: 955.5 ft-NGVD29

3-inch bump to avoid stranding fish in low flows

Plunge Pool 2-feet deep

955.5

956.75 20’ 126’

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Per 100% DDR No. 16 “Sediment Retention Structure 7-foot Spillway Raise” (2013) when all flow passed through the SRS outlet works, the sediment trapping efficiency of the SRS was approximately 92%. When the outlet works pipes were buried and closed in 1998, sediment trapping efficiency of the SRS dropped to approximately 31% and more sediment began to deposit in the Cowlitz River.

The spillway was crest raised by seven feet in 2012 to an elevation of 947 ft-NGVD29 (950 ft-NAVD88) as the first phase of a three-phased spillway raise intended to ultimately reach 970 ft-NGVD29 (973 ft-NAVD88). The seven-foot raise was designed to handle all water, sediment, and debris loadings. The spillway raise was located at the anticipated final location of the ultimate potential 30-foot raise. To maintain the same 7% slope as in the existing spillway channel, the position of the new crest was located be approximately 430 feet upstream (east) of the original crest. The new spillway section was constructed of RCC placed in approximately one-foot lifts. The placement of RCC was done in such a way that reinforcement was not be required. The crest was essentially built in three levels with the lower two levels intended to pass fish within the design juvenile range of low and high design flow rates.

issues (2023)

5/25/2022

Batch plant, and test section can be done prior to entering spillway

Outlet Works can be decommissioned any time

RCC placement volume is 3-times that placed for first raise and the contractor barely made it RCC Placement

River diversion must maintain flow for fish during transition. Siphons may be required to get over first raise

Traffic will be high volume and space is limited

Most labs do not have ERDC validation for the testing of RCC and it takes $ + 90-days

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