Hydrogeochemical Cause of Y G Pavement Subsidence in The

Hyygdrogeochemical Cause of Pavement Subsidence in the Cumberland Gap Tunnel , Kentucky/Tennessee

Jim Dinger, Jim Currens, Randy Paylor, and Steve Fis her Water Resource Section Kentucky Geological Survey University of Kentucky

and Brad Rister Kentucky Transportation Center University of Kentucky October 18, 1996 SITE LOCATION Visual slab settlement at CP 3 (water pooling after tunnel washing, 2001) Survey of tunnel with ground penetrating radar (GPR)

EEiquipmen t 900 MHz. antenna Approx. depth 3 ft.

Data collection location 3 passes per lane CWP, RWP LWP

Data collection density 1 scan every inch

Data collection speed 5 m.p.h. (3 hrs.) Void area beneath concrete pavement southbound tunnel

GPR signal has negative amplitude (noted as black space) because it doesn’t have anything to bounce off of (namely air). GPR Data

• Since 2002, 6 major void area detected in both the Northbound and Southbound bores ( 10 to 116 ft in length )

• Growth of surf ace area i s 100 ft 2/th/ month Shale, Sandstone

Limestone, Sandstone, Mudstone, Shale Chert, and Siltstone Siltstone

Black Shale, Dolomite

PENNSYLVANIAN MISSISSIPPIAN DEVONIAN/ SILURIAN

HENSLEY FM. DARK RIDGE FM. PINNACLE SS. NEWMAN LS. CHATTANOOGA SH .

FT. PAYNE and HANCOCK DOL and MIDDLESBORO FM. CHADWELL FM. PENNINGTON FM. GRAINGER FM. ROCKWOOD FM. Shale, Sandstone

Limestone, Sandstone, Mudstone, Shale Chert, and Siltstone Siltstone

Black Shale, Dolomite

120.00 125.00 130.00 135.00 140.00 145.00 150.00

PENNSYLVANIAN MISSISSIPPIAN DEVONIAN/ SILURIAN

= Void = Cave Cumberland Gap Tunnel, Groundwater Flow Conceptual Model

Northbound Southbound

Impermeable Seal Impermeable Seal

84 ft

Schematic Cross-section is at Station 122+30 with no annular space between tunnel components and bedrock. Flow net is tilted 45°± away from viewer. Scale is approximately 20 ft. per 1 in. Porosity is inter-granular and fracture. KGS Activities at CGT - Groundwater tracingg( (d ye, particle, and spore) - Core borings - Packer tests in core borings - Video logg ing in core bor ings - Pavement/aggregate excavation - Monitoring well installation and water chemistryy( (50 wells) - GW flow: Quality and Quantity monitoring Groundwater Tracing Objectives (May, 2006)

1. Determine if there is a net loss of water from the GW collection system: DYE TRACING

2. Determine flow velocity in the aggregate roadbase: DYE TRACING GLASS BEADS AND LYCOPODIUM SPORES

3. Assess vertical and horizontal EROSIVE flow conditions: GLASS BEADS (0.5 mm diameter; red and green) Cumberland Gap Tunnel Southbound Lane Dye Receptor and Plankton Net Locations Junction Box at CP-1 Junction Box Junction Box Junction Box Junction Box ISCO Auto-sampler at CP-2.5 at CP-3 at CP-4 at CP-5

CP-1.5 CP-2 CP#3.5 CP#4.5

15” Groundwater Collector Auto Sampler, Bug, and Net attht the mmmm Guillotine Gate 123+00 128+75 Concrete Da Da Concrete Concrete 1,056 ft. 250mL 100 gm RWT, 500 fluorescei n 118 ft 452 ft 575 ft gm spores, 688 gm beads 688gm beads 12” Roadway Drain 114.0 ft 178.8 ft. 149.2 ft. 150.2 ft. 134.8 ft. 135.5 ft. 149.5 ft. 150.0 ft.

= detector = plankton net Tracer Injection Schematic

Drive point

Mid-line Junction Box groundwater drain

Groundwater Collector drain

Plankton Net at GG

The other locations were CP-3, CP-2, CP-1 and two at CP-2 1/2 Quantitative Trace Results as Routed Through the Groundwater Collection System Cumberland Gap Tunnel Discharge Velocity Estimate The Fluorescein and Rhodamine WT flow routes have been routed through the groundwater collection syyqstem based on the qualitative results and the assump pption that the first peak on the breakthrough curve represents the first interception by the plume by the mid-line under drain. Revision of Nov. 21, 2006

CP-1 CP-1.5 CP-2 CP-2.5 CP-3CP-3.5 CP-4 CP-4.5 CP-5

1”G15” Ground water C Cllollector 1024ft. 578 ft ? ? amam DDDD Concrete Concrete Concrete

123+00 128+7 118 ft 452 ft 575 ft 5 1056 ft

12” Roadway Drain 114.0 ft 178.8 149.2 ft. 150.2 134.8 ft. 135.5 ft. 149.5 ft. 150.0 ft. ft. ft. Not to scale N GW d rai nage j unc tion box Dye Receptor SbidSubsidence Areas 6” Perforated Underdrain 6” cross dra in Fluorescent dye Concentrations Sampled at G uill oti ne Ga te Beads were recovered, but not ours

1 mm

The plankton nets were functioning effectively. X-ray Diffraction of sample CP-3 003

quartz

calcite

M. mica dolomite Results of the Groundwater Traces

¾ No tracer beads or lycopodium were recovered.

¾ From the qqyg,yguantitative dye tracing, velocity averages 0.02 ft./sec (0.49 cm/sec)

¾ This average is too slow to move 2.6 gm/cm3, 0.5 mm, glass spheres.

¾ Groundwater is NOT lost via “unknown” pathways. Coring Activities, June , 2006

• 5 core boringgys done by the FHWA Technical Group out of Sevierville, TN Depth range from 24.7 to 49.7 ft

• Video logging by KGS

• Packer tests by KGS

• Detailed core descriptions by KGS Scheme for CORE HOLE placement

LEGEND CORE HOLE NthBNorth Boun d Existing pavement hole

CBH#3 138+90

CBH#2 138+60 South Bound 139+01 DIP ~ 42 degrees

* Numbered holes are planned sampling sites. One existing pavement, two existing core holes, and three new pavement holes. 138+50 139+80 122.60 123.13 H2O Fl ow 15–50 gpm VOID VOID >100gpm 122.00 122.32 122.50 122.75 123.00 123.16 123.35 Highway 122.78 Spr. Box Pavement Constr ucts 122.60 123.13 H2O Fl ow 15–50 gpm >100gpm VOID VOID CB-1 CB-4 122.00 122.32 122.50 122.55 122.75 122.85 123.00 123.16 123.35 Highway 122.78 Spr. Box Pavement Constructs

6.6 Rock 6.3 Rock Fracture w/ Qtzite VID disaggregate mat’l 10.3

Southbound 13.9 VOID sm. particles rising or swept horiz. } VID: camera horiz. 10 ft 17.9 VOID 18 Ss VID: Abundant fractures 20.9 Dip ~ 42º 10 ft 23.6 VOID VID: Intense fractures; sm. particles moving up 63% core 25.2 recovery 29 VOID 31.6 VOID 33.5 VOID 37.0 37.0

Rubble 44.6 44.4 122.60 123.13 H2O Flow 15–50 gpm >100gpm VOID VOID CB-1 CB-4 122.00 122.32 122.50 122.55 122.75 122.85 123.00 123.16 123.35 Highway 122.78 Spr. Box Pavement Constructs

6.6 Rock 6.3 Rock Fracture w/ Qtzite VID disaggregate mat’l 10.3

Rubble 44.6 44.4

Upwelling (station 138+90).wmv STRADDLE – PACKER SYSTEM 122+80 123+15 Roadbe d

Packer Position No. 4

Packer Position No. 3

Packer Position No. 2 Groundwater movement

Packer Position No. 1 ( 7-foot interval ) Head Values for CGT Bore Holes: CB3 and CB4 Depth below Pavement to Top of Water, feet 0246 0

5 Core Boring 4 d by d by Pack er l eak ee Core Boring 3 10 3.1 3.04 5.83 val Isolat feet

rr 15 2.61 20 er of inte e Packer, tt hh

t 2.22 2952.95 25

30 pth to cen 2.19 De 35 CORE OBSERVATIONS

• Groundwater INFLOW is involved at ALL LOCATIONS where voids found (BEC tunnel bore mapping or Video (CB -3, 139.15, damp to < 1 gpm reported, BUT upward particle movement))

• Inflow ranges from 5 to > 100 gpm (BEC tunnel bore mapping)

• Lower range of flows are surrounded by “dry” areas (C(BEC tunnel bore mapping ) (cont’d) Observations cont’d • Stratigraphic Zones of FLOW can be wide (CB-1 = 16 ft), BUT more narrow (CB-5 = 0.7 ft)

• Groundwater-head distribution indicates upward flow from bedrock into roadbase aggregate (packer testing).

• Groundwater velocities in void zones sufficient to move sand ppparticles upward and horizontal across borehole (CB-3 and CB-4 video). June –July, 2007 Boil

Coarse Size Reduction

Standard specification # 57

Loss of Fine Size MONITORING WELL INSTALLATION August-September, 2007

To characterize the groundwater quality in each of the 6 major void zones

27 wells in SB bore; 23 wells in NB bore In 2007, 50 Monitoring Wells installed to the Invert (SB = 27, NB = 23)

LEGEND •Existing pavement hole •Existing cored hole; labeled NthBNorth Boun d •Proposed pavement hole •Station Number 185+60*

CBH#3 138+90

CBH#2 138+45 139+33 139+90 138+60

South Bound 139+01 GW FLOW

* Numbered holes are planned sampling sites. 138+50

One existing pavement, two existing core holes, 139+80 and three new pavement holes. Void depth beneath 10 inch concrete pavement CP 5

Southbound

Sta. # Lane Void depth (inches) 128+67 L cwp 40 Groundwater geochemistry at MWs NB01, NB02 and NB03 October and November 2007 (low flow) April 2008 (high flow) Water-Quality Sampling • 144 samples taken on monitoring wells • Most pH > 7.0 BUT < 8.4 • SB: 25/25 wells undersaturated wrt calcite 65/75 samples undersaturated wrt calcite • NB: 22/23 wells undersaturated wrt calcite 53/69 samples undersaturated wrt calcite

TQtiTwo Questions

1. What is the MASS FLUX coming out of each bore in the groundwater system?

2. What is the VOLUME LOSS of dissolved aggregate coming out of each bore? Groundwater discharge: 0.4 to 1.3 mgd 1.5 1 1.4 0.9 1.3

1.2 0.8 hes/hour 111.1 Discharge at cc North Bound CP-1 Weir 0.7 1

0.9 0.6 /sec. 3 cipitation, In ft ee ,, 0.8 0.5 0.7 Discharge at South Bound CP-1 Weir 0.6 0.4 Discharge 0.5 ors Center Pr ors 030.3 tt

0.4 isi V 0.3 Precipitation 0.2 0.2 0.1 CGNHP 0.1

0 0

2/20/08 3/5/08 3/19/08 4/2/08 4/16/08 4/30/08 5/14/08 5/28/08 6/11/08 Calender Date Monitoring Record for Groundwater Drainage System at Cumberland Gap Tunnel Shale, Sandstone

Limestone, Sandstone, Mudstone, Shale Chert, and Siltstone Siltstone

Black Shale, Dolomite

120.00 125.00 130.00 135.00 140.00 145.00 150.00

PENNSYLVANIAN MISSISSIPPIAN DEVONIAN/ SILURIAN

= Void = Cave MASS FLUX FROM BORES

Mass Flux Monitoring Period February 26 through May 1, 2008 1

Mass Flux at Mass Flux at 0.9 North Bound CP-1 Weir Guillotine Gate 0.8 es/hour 1000 0.7

0.6 pitation, Inch pitation, 10-minutes ii

Mass Flux at 0.5 South Bound CP-1 Weir 0.4 Center Prec

Flux, grams/ 100 ss ss Precipitation 0.3 Mas

0.2 GNHP Visitor 0.1 CC

10 0

2/21/08 2/28/08 3/6/08 3/13/08 3/20/08 3/27/08 4/3/08 4/10/08 4/17/08 4/24/08 5/1/08 Calender Date MASS FLUX ESTIMATES

BORE SOLID LOSS VOLUME LOSS (n = 32%)

NB: 1. 44 cf/day 1. 90 cf/day

SB: 0.63 0.83

Question: What is TDS value of NB cave water? REMEDIATION ?

• Excavation of #57 limestone and replace with granite

• Grout through holes drilled in pavement

• Lower groundwater table beneath #57 limestone roadbase aggregate

Void CP 8 ½ : Pre-grouting Nor thboun d cen ter w hee l pa th January 2008 Grouted Void CP 8 ½ Nor thboun d cen ter w hee l pa th May 2008

Partially Existing void Existing Void not filled filled void. filled with grout. with grout < 1in . Void remains >1 in. Void remains North Bound CP3 (123.26)

• 82% voids filled with grout

• Remaining voids less than 1 inch in depth (18%) North Bound CP 5 (128.96)

• 80 % voids filled with grout

• Remaining voids less than 1 inch in depth (20%) Southbou nd Bo re G PR sca nnin g

– No voids present at CP 3 (granite replacement)

– Grouting success at CP 5 and 8 ½ cannot be determine b/c foam grouting (2002)

– GPR scanning will be performed on semi- annualbl bas is for a ll areas TO BE CONTINUED ------PROCEED WITH CAUTION