Att_3_Industry_Day_Presentation_2_Design_Team_5.pdf

Hyrum Dam Industry Day Design Presentation

July 31st, 2024

Agenda

• Introduction

• Current operations

• Spillway concrete design

• Geology presentation

• Foundation treatment design

• Excavation slope stability

• Cofferdam design

• Dewatering design

• Water Conveyance design

• Demo concept design

• Construction Schedule

•Located on Little Bear River, near Logan, Utah

•Provides irrigation and recreation

•Completed 1935

Existing Spillway Key features:

• Concrete trapezoidal chute slab and walls cast on grade

• 3, 16x12.5’ radial gates (with flashboards)

• Broad crest elevation 4660

• Gates capacity ~ 11,500 cfs

@El.4679

• Chute capacity ~ 9,000 cfs

Current Operations •Reservoir

• From Dec to mid April, it is difficult to draw below 4660

• https://www.usbr.gov/uc/water/hydrodata/reservoir_data/site_map.html

•Average daily inflows

•Average spillway releases

•Water deliveries – April 1 to October 1

• East Field Canal

• Capacity – 45 cfs

• Normal flows: max 35 cfs

• Hyrum Feeder Ditch

• Capacity 12 cfs

• Normal flows: 5-8 cfs

• Wellsville-Mendon Upper (pump) canal

• Capacity 15 cfs

• Wellsville-Mendon Lower canal

• Capacity 85 cfs

• Major benefits to maintain deliveries for both Eastfield Canal Siphon and Hyrum Feeder Ditch during construction

Contractor Use Area

Spillway Concrete Design

Crest Features

1. Large Battered walls

1. ~26ft high

2. 2ft at top, ~6.25ft at base

2. Large Pier

1. 4ft consistent width

2. 26ft high

3. Pier nose

3. Reinforcement

1. Bundled Bars with no splices for the walls

2. Bundled bars in the slab

4. Concrete Corbel

1. Six heavily reinforced corbels, including welded rebar.

2. 3 steel radial gates

5. Fiber Reinforced Concrete in slab (TBD)

Crest - Ogee

RSMC Ogee

2 Vertical Curves

General

1. RSMC with temperature control plan required in many placements including all cutoff walls, transitions, crest (including ogee), and stilling basin.

1. Placements as thick as approximately 6.5 feet in walls and slab.

2. Battered walls range in height from about 36’ to 14’

3. Vertical walls are 11’ tall

4. Unique Reinforcement Joint details

5. Shear crossties are required everywhere there are bundled bars by ACI 350.

6. Concrete to be placed on significant slope

7. Stilling Basin walls are 36 ft tall and 5.25 feet wide at the base tapering from 2 feet at the top.

8. Walls will likely need to be poured in lifts.

Drainage

1. Drainage consists of sand and gravel surrounding 8” and 10” HDPE pipe

1. ADS N-12 pipe

2. Pipe is perforated and unperforated.

3. Drainage system is extremely important and will be video inspected multiple times in the construction process.

4. Every lateral and beginning/end of longitudinal drains will have a cleanout.

1. Cleanout at grade to be protected by traffic box.

5. Air vents are located at beginning/end of each drain system.

Drainage – Cutoff Walls

1. Creative construction methods required to place drainage materials on adverse angle after the cutoff wall has been placed.

2. Localized excavation may be required to place cut off walls

Is there an advantage to multiple team placements?

1. Concrete will be placed by two teams. One team will start at the flatter portion of the chute (Team I) and one team will start at stilling basin (Team II).

2. Special care will need to be taken at the intersection of the upstream pour and the downstream pour.

Geology

Regional Geology

• Hyrum is located in the Basin and Range Physiographic Province characterized by regional extension resulting in normal faulting (N-S) forming horst and graben (basin and range) topography

• Cache Valley is a graben type valley formed by north-south trending faults along the eastern and western edges of the valley

• Faults are covered by Quaternary deposits

• Pleistocene Lake Bonneville

• Several stages of lake levels

• Highest Lake Level (El 5100)–overflowing out Red Rock Pass to the

• Columbia River Basin

• The breach at Red Rock Pass caused the Bonneville flood that scoured

• the bedrock lowering Bonneville Lake to the Provo Level (El 4740)

• The Big Blue-Deep Lake Bonneville Revealed

• « Tooele Transcript Bulletin – News in Tooele, Utah (tooeleonline.com)

Hyrum Reservoir

Estimated to be up to 800 feet thick

• Lake Bonneville: Geology of Southern Cache Valley, Utah

• By J. STEWART WILLIAMS

GEOLOGICAL SURVEY

• PROFESSIONAL PAPER 257-C

Cenozoic geology of a part of the area inundated by a late Pleistocene lake, Proposed Spillway Geology

Existing Spillway Geology

• Provo Clay (Qpb)

• Erodible when saturated

Existing Spillway Geology

• Spillway constructed on Provo Clay, a silt/clay member w/ few gravel beds

Excavation

•3:1 Inlet slopes in clay •2:1 with 10’ benches further down •2:1 around stilling basin

• Phased for dewatering •Slope monitoring

Excavation - Upstream

Excavation - DS

Excavation – Downstream

•Dewatering and cutoff wall required for stilling basin

•Phased approach discussed in dewatering portion •Major benefits to meet deliveries for both Eastfield Canal Siphon and Hyrum Feeder Ditch

• April 1 to Oct 1 for water deliveries

• Temporary Bypass canal for East Field included in phased approach

Foundation Treatment

•Spillway gross bearing pressures from 750 to 3250 psf

•Overconsolidated, varved clay foundation

• High horizontal permeability

•Aggregate Pier ground improvement selected to minimize differential settlement between spillway panels

Aggregate Pier (AP) Design

• Installation of stiff columns of compacted aggregate

•AP’s act as stiff “springs” to remove load from the foundation soil

•Spacings altered based on anticipated loads

• Tighter spacing = stiffer foundation

• Looser spacing = softer

• Optimizes costs and schedule

AP Background Drilled AP’s required – no displacement methods

AP Layout

~850 AP’s from 12 to 28 feet below excavation grade

AP QA/QC

•High risk project with additional requirements than normal

•3 individual pier modulus tests

• Sacrificial AP’s

• 1 full-scale load test

• Production AP’s

•Bottom Stabilization Test (BST) on each AP •Dynamic Cone Penetrometer Testing (DCPT)

• 3 tests in upper 1/3 of each pier until five piers pass

• 1 test per pier

Cofferdam

•Limited outlet works capacity prevents reliable reservoir control below 4660

• Spillway inlet excavation extends to ~4645

• Install sheet piles at EG 4660 to 4680 for wave runup

•Place compacted stability berm to 4664 •PCZ-28 or equivalent

• If ice loading occurs add to stability berm (unlikely)

Cofferdam

• Can we install sheet piles with the reservoir above 4660?

Dewatering

Cutoff

• Surrounds excavation to prevent shallow groundwater from entering the stilling basin excavation.

• Contractor-designed, Reclamation provided alignment and depth.

Deep Wells

• Installed along the outer rim, dewatering bench, and in the center of the excavation.

• Removes groundwater from deeper layers.

Well Points

• Installed along the Phase 1 excavation to remove pressure from a thick clay layer within the Qal.

Temporary Observation Wells

• Installed within and outside of excavation to verify adequate removal of water.

Passive Wells

• Installed along upper chute to drain Qpc pressure into the underlying Qbu.

Unwatering

• Unwatering systems for stilling basin, upper chute, and crest structure.

• Will need to be robust for stilling basin work

• Contractor-designed

Dewatering Design Components

Construction Phasing Phase 1

• Install:

• Cutoff

• Temporary observation wells

• Exterior deep wells

• Excavate to El. 4568

• Install:

• Remaining deep wells

• Well points

• Cut temporary observation wells down within the excavation as needed.

Phase 1

• Install:

• Cutoff

• Temporary observation wells

• Exterior deep wells

• Excavate to El. 4568

• Install:

• Remaining deep wells

• Well points

• Cut temporary observation wells down within the excavation as needed.

Phase 2

• Remove:

• Well points

• Interior deep wells

• Interior temporary observation wells

• Excavate to total depth

Stilling Basin – Phase 1 45 Deep Wells

18 Temporary Observation Wells

68 Well Points

Cutoff – approx. 1230 feet long Contractor-designed

Dewatering Bench El. 4568

Unwatering System Contractor-designed

Stilling Basin – Phase 2 Remove 12 Deep Wells

Remove 6 Observation Wells

• Cut down interior OW as encountered

• No need to be read during

Phase 2 excavation

Remove all Well Points

Excavate to total depth

Upper Chute 38 Passive Wells

9 Observation Wells

Unwatering System Contractor-designed

Well Details

Drilling Methods

• Caisson or sonic for all wells

• Hollow Stem Auger drilling not allowed due to potential smearing of the clay interbeds in the Qal

Screen Length (ft)Casing Dia. (in)Borehole Dia. (in)Slot Size (in)Filter Pack

(PVC VEE-Wire)

(Sch. 80 PVC)10.50.02#16/#30Deep Wells

(Sch. 80 PVC)

(Sch. 80 PVC)40.01#20/#40Well Points

(Sch. 40 PVC)

(Sch. 40 PVC)60.02#16/#30Temporary

Observation Wells

Varies (Sch. 40 PVC)

(Sch. 40 PVC)60.02#16/#30Passive Wells

Well Information

Water Conveyance

Spillway Crossings (Water Conveyance Designs)

Existing Conditions:

Maximum Flow Rate (cfs)

Nominal Flow Rate (cfs)MaterialGeometryConveyance

4535 to 40Unlined Earth Trapezoidal

Canal East Field

Canal

125 to 8PVC (DR-32.5)18-inch-dia.

Pipe

Hyrum Feeder Ditch

• Two existing water conveyances cross the proposed spillway alignment.

• For these crossings, inverted siphons will convey water underneath the new spillway

Spillway Crossings (Water Conveyance Designs)

Principal Design Considerations:

• Minimize hydraulic losses introduced by the addition of the inverted siphons (pipe friction, bend, and entrance/exit losses) – assure existing water convenance capacities are met after addition of features

• Reinforced Concrete Pressure Pipe (RCPP) – selection based on demonstrated performance at other similar installations – CLSM embedment and backfill for length underneath spillway (potential seepage mitigation)

• Pipe diameter set as large as practical while maintaining 3 feet/second average flow velocity

• Conventional blowoff structures not deemed practical for either siphon

• Infrequent need for unwatering – submersible pump options available (e.g. landfill leachate pump)

• Construction difficulties – protection of standpipes during spillway construction

• Grading challenges – gravity drain to daylight

Spillway Crossings (East Field Temporary Bypass)

Design Features:

• Temporary realignment of East Field Canal to maintain water deliveries during spillway earthwork and dewatering construction activities

Spillway Crossings (East Field Canal)

Spillway Crossings (East Field Canal)

• Type 1 Concrete Transitions at inlet and outlet

• Capacity set to provide a minimum freeboard of 2.6 feet at inlet for maximum flow rate

Spillway Crossings (East Field Canal Realignment)

• Interim canal alignment providing deliveries prior to existing spillway removal by connection to existing siphon

• Final canal alignment after existing siphon and spillway abandonment

Spillway Crossings (Hyrum Feeder Ditch)

Spillway Crossings (Hyrum Feeder Ditch)

• 6-foot-diameter precast concrete manholes provided at inlet and outlet

• Existing design data for the Hyrum Feeder Ditch is limited regarding the non-pressurized flow capacity of the existing 18-inch-diameter PVC pipe

• Reported capacity = 12 cfs

• Estimated non-pressurized full flow capacity (based on original Hyrum Feeder Ditch slope) = +4 cfs

• Inverted siphon was sized to deliver 12 cfs, limiting added hydraulic losses to be less than 1-foot

• Manhole structures provide necessary inlet submergence to prevent blowback, and allow for venting of air carried by flows upstream of the siphon and purging of air carried by flows through the siphon

Spillway Demo Design

•Upstream may require a cofferdam – design by Contractor

•Remove all concrete, gates and drainage down to Sta. 8+75.3

•Downstream of Sta. 8+75.3, partial demolition •Fill chute with specified materials to existing grade

• Drainage system for any seepage that may develop

HMR0

Slide 66

HMR0 I added this Henrick, Michael R, 2024-07-16T21:32:02.284

•Remove all concrete, gates and drainage down to Sta. 8+75.3

•Downstream of Sta. 8+75.3, partial demolition

•Embankment material in place of concrete removal

•Embankment material in place of concrete removal

Construction Schedule

Key Work Restrictions

• Outlet channel downstream of stilling basin shall not be constructed until stilling basin complete.

• Concrete placements from Sta. 3+73 to 11+25 shall progress from downstream to upstream.

• Contractor must provide access to the downstream property during the entirety of construction

Hyrum Construction Sequencing

Mobilization

Contractor Designed Cutoff Wall & Dewatering

Installation of Two Siphons

Cofferdam Construction

Foundation Treatment

Upper Chute

Upper Transition

Stilling Basin

Crest

Inlet

Lower Transition

Lower Chute

Install 3 Radial Gates

Roadwork

New Spillway Able to Pass Emergency

Flows

Remove Existing Spillway

Bridgework

Questions?