US Army Corps of EngineersBUILDING STRONG®

Kenneth Darko, PhD., P.E., P.G.Geotech/Water Resources, LRH

Seth Lyle, P.E., P.G.USACE DSMMCX/LRD DSPC

Erich Guy, Ph.D., P.G.Geotech/Water Resources, LRH

Michael Nield, P.G.USACE DSMMCX/LRD DSPC

Carol Tasillo, P.E.USACE/DSMMCX/LRD DSPC

Sean Carter, P.E. PGGeotech/Water Resources, LRH

Kona, HI22 September 2016

Design, Construction, & Verification of a Partial-Depth Seepage Barrier through Glacial Outwash

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Presentation Outline

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• Project Background• Performance• Major Rehablitation• Seepage Barrier Construction Verification Performance Monitoring

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35 Flood Control Damsw/ 24 Appurtenant Levees & Dikes 9 Navigation Locks & Dams(OH, WV, KY & VA)

Bolivar Dam

Huntington District Boundary

US Army Corps of EngineersBUILDING STRONG® http://www.dnr.state.oh.us/

portals/10/pdf/glacial.pdf

Glacial Geology

Illinoian Ice Margin

Wisconsin Ice Margin

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(El. 950 to 920 feet) Onsite Borrow Area for seepage blanket extension/augmentation work – downstream of right abutment

Left AbutmentRight

Abutment

Dam FoundationEmbankment

~200 feetfoundation thickness

~45 ft. terrace thickness

NOTE: Profile copied from original as-constructed drawings; actual foundation depth is shallower (~120’ thick) from ~Sta. 19+00 to the right abutment.

Typical glacial deposits range from poorly graded sand, to poorly graded gravel, to well graded sands and gravels. Time must be spent regionally in the field to observe/evaluate geology.

Continuous (>1000 ft) “sugar sand” in Wisconsinan outwash, Massillon, Ohio.Continuous erodible sands are typical in this depositional environment, and occur as overbank,

channel-infilling, bar, and distal plain deposits (e.g. Illinoian outwash).

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Glacial Outwash: Sand & Gravel

Bolivar Dam – Typical Cross Section

NORMAL - 910

UNUSUAL - 964

EXTREME (PMF) – 982.5Upstream Downstream

IMFCP 949

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Bolivar Dam-Major Features, Ohio

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Left Abutment

Right Abutment

Terrace

Main Embankment

Spillway

Intake Tower

Outlet Channel

Back-Channel(old SandyCreek)

Seepage Berm & Relief Wells

~El. 902

Upstream Ground~El. 910

Terrace Ground~El. 950

Sandy Creek~El. 898 (dry dam)

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Dam Performance

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• 1969 –Numerous boils at 940 pool

• 1975 Uncontrolled underseepage at 936 pool

History of Uncontrolled Seepage

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Pool of Record 14 Jan 2005

Pool Of Record El. 951

55.5% Project Storage Capacity

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Terrace Foundation Sand Eroded Out

Emergency Filter Placement on Terrace

Overflowing relief well nearing inundation by Dover Dam pool

Artesian flow from piezometer even with extension

Flow through open joints in bedrock in left abutment of dam

Pool of Record 14 Jan 2005

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Mar 2008 – El. 936

2008 & 2011 High Water Events

March 2011 (pool 946’, tail 901’) photo with max PZ readings indicated. A lot of seepage also discharging through 2’ collector/gravel drain and into 6’ sand berm; seepage quantity significantly greater than that visible in photo.

PZ D-67, STA 50+70TOG: 926.4’, Tip: 914.2’Max PZ 03/11: 920.5Max PZ 01/05: 924.4’PMF (linear) ~ 945-957’

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Major Rehablitaion

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Relief Wells & Berm (1981-1982) 35 Relief wells Seepage berm, Sta. 25+00 to 60+00 Toe Drain, 24” diam.

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Spillway Widening & Parapet Wall Construction (1989)A. 3.5 ft. Parapet Wall on upstream

crest.B. Upstream stability bermC. Spillway widened to 540 ft.

270 ft

540 ft

A

B

C

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SANDY CREEK

Major Rehabilitation(post Pool of Record)

1) Terrace slope filter (2009)2) Rehab. wells (prelim.) (2009)3) Downstream filter berm extension (2012)4) ADAS Ph. 1 & 2 (2013-14)5) Seepage barrier & abut. grout curtain (2016)6) ADAS Ph. 3 (2016-17)

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Instrumentation Design and Construction

19 Tail Water AutomatedRelief Well System Automation

Piezometer Automation

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Pool: 982 ft

Tailwater: 930 ft

Seepage Barrier Design

Pre Seepage Barrier

Post Seepage Barrier

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Seepage Barrier Construction

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Site Plan – Seepage Barrier Construction

March 2016 Pool

(normally dry dam)

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Generalized Cross Section w/Seepage Barrier

UPSTREAM DOWNSTREAM

IMPERVIOUS CORE PERVIOUS SHELL

PERVIOUS SHELLTEMP. WORK PLATFORM

Top of Seepage Barrier 959 (varies)

STONE SLOPE PROTECTION

IMPERVIOUS BLANKET

Barrier ties into Impervious Core

SEEPAGE BARRIER

GLACIAL OUTWASH (SP to SM w/gravel zones)

144’ Depth (varies)

Bottom of Seepage Barrier 815

GLACIAL OUTWASH (GP, GM, GW w/sand zones)

AVG. TOP OF ROCK = EL. 750

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Construction Contract Performance based specs. open to mix-in-place or excavation and

replacement methods. Procured based on best value procedures. Fixed-firm-price contract. Contract awarded to Treviicos South (TIS) for $44.3 million TIS proposed panel method excavated with clamshell & hydromill and

backfilled with plastic concrete. Proposal incorporated into contract. Foundation drilling and grouting subcontracted to TerraFirm Earthwork subcontracted to Massillon Construction & Supply Notice to Proceed: 21 May 2014 Barrier Completed: 24 May 2016

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2 ft. minimum width; 144 ft. depth; 6 in. minimum overlap if panel method utilized

Continuity and Homogeneity• Continuous – no open joints, seams, or cracks• Homogenous – no voids, honeycombs, cold joints or unmixed

material >3”

In-place permeability• ≤1 x 10-6cm/s @28 days from falling head test in borehole

In-place Strength• Minimum UCS of 750 psi at 28 days on cores from verification holes• UCS based on 10 point moving average with no test below 500 psi

Chemically compatible with soil and groundwater

Seepage Barrier Requirements

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Construction Approach – Work Platform & Guidewall Contract Plans minimized excavation into the embankment 68 ft. wide work platform consisting of compacted granular soils from onsite borrow area 1 ft. thick aggregate working surface (8” of #1’s under 4” of road base (ODOT #304’s)) 4 ft. deep x 1 ft. wide concrete guidewall

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Construction Approach - Excavation Panel method excavated with clamshell (upper ~15 ft.) & hydromill 25 ft. primary panels (3 bites), 9.2 ft. secondary panels (1 bite); primary later 30 ft. (5 bites) 3 foot minimum width and 16-inch overlap at work platform surface (as proposed by TIS) Stabilizing fluid maintained within 3 ft. of top of guidewall; monitored 24/7

During Production Phase: Excavated at night and placed

during day; work 6 days per week In Soil: 1 primary or 2 secondary

panels (147 ft. deep) completed per day

In Rock: avg. 5 ft./hr excavation rate; mudstone (shale, claystone) slowed production due to frequent removal for cleaning of teeth

End-stops installed at ends of primary panels during backfill to facilitate start of excavation in secondary panels; removed ~4-24 hr. after placement

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Construction Approach –Excav. & Cleaning

Sequence #5 Sequence #9

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Construction Approach – Excav. Verification 2 independent methods (Koden and DMS (Drilling Mate System on hydromill)) Excavation report submittal approved for each panel prior to placement Panel depth, width and overlap (for secondary panels) presented

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Construction Approach – Panel Backfill Tremie concrete placement: 3 pipes for primary panels and 1 for secondary panels;

10 in. diameter pipe; 10 CY per truck Pipe joints sealed with rubber sleeves, flexi-wrap, and duct tape; minimum 10 ft.

embedment maintained throughout placement Pipes set 6-9” from bottom of panel at start; saturated foam plug used

Onsite wet batch plant – 116 CY/hr capacityDual Horizontal Shaft Mixer (>90 sec. mixing time used)

Primary panel placement

Primary panel placement

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Construction Approach – Placement ReportProduction placements: Primary Panels: ~5-6 hr. duration and ~ 530 CY placed Secondary Panels: ~2 hr. duration and ~160 CY placed

Secondary panel placement

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Construction Approach – Placement Report KTR and USACE tracked depth to SBBM after each round of trucks vs. expected depth

based on Koden data to note any anomalies (e.g. trench wall slough) during placement

Placement curve tracks closely with expected curve based on Koden survey data of excavation

Avg. overpour Koden data:primaries = 3%secondaries = 6%

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Seepage Barrier Backfill Material (SBBM)

Plastic Concrete constituents:

• Type I Portland Cement

• Grade 100 Ground Granulated Blast Furnace Slag

• Bentonite – BaraKade SP WY sodium

• Water – on-site relief well

• Natural Sand – local quarry

• AASHTO #8 Natural Stone – local quarry

• Admixtures - Lamsperse HS - dispersant for bentonite-cement

slurries- Grace Recover - hydration inhibitor

NOTE: KTR mix design (Raffaella Granata, TREVI)

Quality Control Checks• Slump• Temperature• Air Content• UCS• Permeability• Aggregate moisture

& gradation

QA check of slump during secondary panel placement

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All 28 day QC samples well exceedthe 500 psi minimum required for

verification cores (in-place barrier).

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Seepage Barrier Verification

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Demonstration Section – Profile w/Verification Borings

Spec required verification boring (VB) every 50 LF and 1/3 of the VB’s to be angled (30 degrees) w/locations selected by USACE.

KTR elected to drill additional VB’s along panel joints to further evaluate joint conditions.

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Demonstration Section – Panel Joint Concerns

Poor quality concrete recovered in upper portion of panel joint in the area of end-stop usage.

Soft clay-like material in joint of verification boring V2254; this was one of the worst joints.

Note: acceptable results from all holes drilled within panels; only joints between primary and secondary panels were of concern. Issues early on with concrete setting up prior to completion of pour in primary panels.

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Demonstration Section – Panel Joint Concerns

Optical televiewer image of borehole wall from ~7-9 ftdepth in V2254.

Optical televiewer image of borehole wall from ~26-28 ftdepth in V2254.

Note: dyed red concrete was later used to backfill secondary panels to help distinguish primary from secondary panels at joint locations.

Joint shown in previous slide

Note: Joints were remedied by reaming hole to 9 in. diameter and backfilling with microfine grout.

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KTR Changes to Methods following Demo. Section1. Shorten end stops used in primary panel construction from 15 ft. to 4 ft.

2. Use of thinner stabilizing fluid during secondary panels construction.

3. Improve joint cleaning in secondary panels using new poly brush tool (or poly brushes attached to

clamshell for over-excavated panels) in addition to steel brushes used previously.

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Improved Joints Conditions following Method Changes

Optical televiewer image of borehole wall in V4302 at 63-65 ft. depth.

Core sample for unconfined compressive strength testing from 63.6-65 ft. depth in V4302.

Optical televiewer image in V2317 at 19-21 ft. depth.

EXTENDED DEMONSTRATION SECTIONPRODUCTION SECTION

PRODUCTION SECTION

Primary Panel (gray)

Secondary Panel (red)

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Seepage Barrier Performance Monitoring

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Performance Monitoring & Seepage Modeling

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Questions

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