Colorado Bridge Approach Slab Settlement Lift

Bridge Approach Slab Settlement Repair – Crystal Valley Parkway, CO

Asphalt Pavement Lift of a Bridge Departure where the Subgrade had settled and the pavement needed to be lifted

In Castle Rock, CO, along the Crystal Valley Parkway, the Town of Castle Rock, CO was experiencing bridge approach slab settlement of 1,900 SF of bridge approach, departure, and sleeper slabs on two bridge ends and adjoining pavement. Settlement of adjacent sidewalk had also occurred causing an unsafe driving situation as well as dangerous conditions to pedestrians utilizing the crossover sidewalk area. The unstable subgrade reaching below the sleeper slab would need to be treated to stabilize the area before mill and fill of asphalt pavement could be performed.

Bridge Approach Slab Settlement Solution

CST partnered with the Town of Castle Rock, utilizing their Deep Injection process to treat unstable soil, lift the slabs, and realign sidewalk and pavement areas. Dynamic Cone Penetrometer soil tests were performed to correctly identify the weak soil zones. Injection tubes were placed at depth and expanding structural polymer injected to densify and provide stabilization of subgrade soils. Once the soil is stabilized, injections are continued to provide lift and realignment of the slabs and overlying pavement. The CST Deep Injection process provides proper support to the soil and heavy sleeper slabs to mitigate against future bridge approach slab settlement and movement, while also providing a solid subgrade for pavement.

Repairs were made in two shifts while allowing traffic to continue utilizing the area vs. time and money spent to reroute. Foundation soils were significantly strengthened to mitigate against future settlement. Bridge approach and departure slabs were lifted back to original elevation as well as stabilization and lift of sidewalk areas. Subgrade soils were quickly and effectively stabilized to provide a strong base for asphalt pavement mill and fill operations. The added benefit of water cutoff effectively arrests soil erosion within the area. Significant savings to municipalities and tax payers vs. alternative methods of rip out and replace. Extended use life of the bridge, sidewalk, and pavement.

Earthen Dam Repair – Moorcraft, WY

On June 9, 2010, Concrete Stabilization Technologies, Inc. received a call from Moorcroft Wyoming landowner, Ed Scott, concerning an urgent dam repair project near his home. A muskrat had burrowed a hole through an earthen dam and due to heavy rain in the previous days, the water level behind the dam had risen and a significant amount of water was flowing through the burrow at the toe of the dam. When the leak was discovered, it was flowing at such quantity and velocity that it was washing away 50 pound bags of Sackcrete, Mr. Scott had placed upstream to attempt to halt the flow. Once Mr. Scott realized this was doing nothing to stop the flow, he attempted to push dirt into the hole using a rubber tired dozer as well as pack the hole with a soil and bentonite mixture. This slowed the flow down considerably, but did not stop it. If this dam had washed out completely, it would have blocked the primary access to his home.

Ed Scott is an engineer with Consolidated Engineers, Inc., Gillette, WY, who had worked with Concrete Stabilization Technologies, Inc. in the past and knowing about our High Density Polyurethane technology, gave us acall to repair the dam.

On June 10, Mr. Scott met with CST’s crew supervisor Damien Archey and a crew of two men at 9:00 a.m. to investigate the leaking dam site. Prior to meeting, the crew actually had no details on the dam other than it was leaking. When the CST crew arrived at the dam site, they realized they were dealing with an earthen dam, and not a concrete dam. Ed let Damien know that he had attempted to stop the leak by pushing dirt against the hole. The dam was not leaking at the time of this investigation, but the crew could see approximately where the hole had been. The water level was at five feet on the lake, and where the water came out the other side, it was at 25 feet. Damien’s initial thought was to densify the soil from below the hole and collapse the void while strengthening the surrounding area. Probes were put into the soil and wet soil was found at minus five feet with a zone of extremely soft soils. Another area was probed at approximately 20 feet by six feet but results were only found in the first area. Since the water level was at five feet, Damien felt they were in the right spot. Also, this area was in direct alignment with where the water had been leaking out. It was decided to set probes at minus nine feet to start compacting the soil from below the leak. As the crew was injecting, they pulled the probes up in one foot increments while monitoring the surface for movement on the soil. This technique had been used while working with Florida ICR. After shooting at minus 9 feet, probes were set at minus 5 feet and injection was done until they saw soil movement or material at the surface. The crews observed both and when the final probe was shot; the material would not stay in the ground, but came up through fissures in the soil. This indicated that there was no other place for the material to go and the area had been successfully compacted while sealing off the leak. Post soil testing was done and confirmed that it had been successful. Before the start of the work, the standing water at the toe of the dam was clear. After the work started, the water became muddy and two hours after completion, there was no standing water at all at the toe. The next morning, the area was dry. In the weeks following the repair work on this dam, the area again received significant rain fall. As of June 23, 2010, the only water at the toe of the dam appeared to be from the rain. There are no further leaks according to the land owner Ed Scott. The repair used approximately 300 pounds of material and was completed by 11:30 a.m., just 2 ½ hours from start to finish.

Dry Fork Mine Rail – Gillette, WY

Load Out & Rail Void Fill & Stabilization

CST Deep Injection Technologies were employed to fill voids and stabilize the floor in the Train load-out building and along rails in the loading area of the Dry Fork Mine in Gillette Wyoming.

Floor stabilization, void fill, and sub-grade stabilization of the building and adjacent track area were completed in three shifts by Concrete Stabilization Technologies, Inc., providing the customer with a permanent solution for their production site.

Douglas County Sheriff MSE Wall Repair – Highlands Ranch, CO

Douglas County Sheriff MSE Wall Repair – Highlands Ranch, CO

Concrete Stabilization Technologies, Inc. partnered with the Douglas County Facilities Management division of Douglas County, CO to stabilize the MSE walls at the Douglas County Sheriff Sub-Station in Highlands Ranch, CO.

CST was referred by a geotechnical engineering firm to provide a solution to stabilize portions of distressed MSE wall. The geotechnical report indicates low density soils between base of wall and top of storm sewer pipe installed approximately 16’ prior to MSE wall. A section of the MSE wall was slated to be rebuilt after soil stabilization project was completed.

Patented processes were used to increase bearing capacity and stabilize the West and East MSE wall in the sewer trench area of the facility for an area of approximately 60 LF. CST’s deep injection method was performed to reinforce low density soils between top of storm sewer pipe and bottom of MSE wall. The distressed MSE wall was monitored with laser levels during the injection of expanding structural polymer into the underlying soils. Injections were also performed around a manhole to void fill and seal joints.

Video camera inspections were done before and after injection to verify pipe condition. The patented injection processes used in this stabilization project saved the customer from excavating and possibly replacing the pipe.

This project was completed on time and on budget!

Layland Canyon Mine Reclamation – Lincoln County, WY

Concrete Stabilization Technologies, Inc. (CST) completed a high profile in-situ compaction and water control project at the Layland Canyon Phosphate Mine in western Wyoming. The Layland Canyon Mine area is an abandoned mountainside phosphate mine located in Lincoln County, near Cokeville, Wyoming. The mass grading and reconstruction of the slope area of the mine was being completed as part of the State of Wyoming’s reclamation of abandoned mine land. Concrete Stabilization Technologies, Inc. sub-contracted with Oftedal Construction, Inc. to perform the injection of Expanding Structural Polymer into areas of the high wall face area of the mine, in order to help steer water off the zone next to the face by compacting the soils and mitigating the settlement and water inflow into the backfill and rock interface. With topsoil being placed over this area, a desired shingle effect was created beneath to divert water, and help stabilize and control future erosion of the reconstructed area.

Concrete Stabilization Technologies, Inc. Regional Engineer Roy Mathis worked with Chris Walla, P.E., of RESPEC Consulting to develop the procedure and specification for injection of Expanding Structural Polymer (ESP) that was successfully used on this project. Crews joined Oftedal Construction, Inc. for a site-specific safety meeting, and then drove to the injection location to begin placing probes and prepping the CST injection equipment. After a field adjustment by AVI’s Field Engineer the first set of injections were placed on the north end of the high wall, 11 feet south of Station 17+70, 59 feet north of the original plan. Due to wider top bench, injection points were moved 30 to 40 feet north of the original injection plan. ESP design was adjusted from three injection rows, to two rows. The second row was adjusted with increased material per injection location in order to ensure good compaction and the material spread between injections into the backfill and against the high wall. Injections were made at three foot and 10 foot depths.

CST crews were highly efficient in completing the project and devising the best solution based on actual field conditions once the work began. In consideration of water runoff, adjustments were made to meet the goal of shedding water away from the high wall. Slope changes were taken into account and injection points altered from the original 2 foot area to 4 foot along the slope and wall in order to provide maximum effect from the stabilization of the soil. Adjustments to compensate for blowout were also made at the 10 foot level.

The CST ESP was injected into the high wall area of the mine site, successfully compacting, stabilizing and providing erosion protection for the abandoned area. Even as inclement weather rolled in, the work was completed in three days. A total of 1100 lineal feet of compaction and water control was completed at the interface of the high wall and fill material to assure stabilization of the soils and provide excellent results for the successfully reclaimed mining site.

Team Members:

  • State of WY DEQ Abandoned Mine Lands Division, Owner
  • Jim Murphy, P.E. AVI Engineering, Inc.
  • Chris Walla, P.E., Environmental Manager, RESPEC Consulting & Services
  • Roy Mathis, CST Consultant & CST Project Manager, Concrete Stabilization Technologies, Inc.
  • Matt Otterby, Project Manager, Oftedal Construction, Inc.
  • Tomas Ramos, Project Superintendent, Concrete Stabilization Technologies, Inc.

Battle Mountain Highway Frost Heave – Encampment, WY

Abstract

This project investigated a novel procedure to reduce or prevent subgrade freezing non-destructively by injecting a two part rigid polymer foam at the top of the subgrade. Controlled injection of a CST expanding structural polymer foam created a continuous three inch thick layer of insulation that significantly reduced the heat loss from the deeper soil and prevented the upward movement of water from the warmer regime under the foam to the upper frozen regime above the foam, preventing segregational freezing in the upper zone. The construction time for the 170 foot section was one week for injection and milling the surface. Construction was contained in one lane, leaving a lane open for the entire duration without a detour, increasing safety and minimizing impact for the driving public.

Additionally, a procedure is developed for estimating the thickness of the foam layer required for other sites with different average temperatures.

Objectives

  • Can foam be injected nondestructively to level the road surface and make the road safer to drive without full reconstruction?
  • Will the foam layer provide a sufficient thermal barrier to prevent heat loss and reduce frost heave?
  • Will a continuous layer of foam create a barrier to vertical water movement and reduce spring thaw degradation?

Background

  • This section of Highway WY-70 was constructed in the early 1980’s. The highway crosses a crystalline caprock ridge outcrop that the contractor had difficulty removing.
  • The contractor was allowed to alter the design to leave the ridge intact and place three feet of compacted silty sand fill over the rock with the sub-base and base course on top over a distance of 150 feet.
  • Lateral drains and cross drains have not completely removed the water under the pavement. .
  • The combination of a frost susceptible silty sand, extended cold temperatures and the availability of water provide the necessary pieces for segregational frost heave.
  • Measured heaves of three inches and reported heaves of four to six inches created a dangerous bump over a short distance of 75 feet. In addition, a drain installed over the caprock was backfilled with non-heaving backfill which created a dip significant enough to flip snowmobiles off of trailers when traveling faster than the posted speed.

Proposed Solution

A standard technique to control frost heave is to place several layers of foam insulation panels below the sub-base course. This requires a full reconstruction of the site. A process was proposed to inject a three inch thick layer of a two part structural polymer foam at the bottom of the sub-base without removing the existing road surface.

Construction

Concrete Stabilization Technologies, Inc (CST) injected the foam through a series of 3/4 inch diameter, 18 inch deep holes drilled through the road surface on a 6 foot grid. Three inches of foam were injected over the area with the most heave. Additional injections provided tapered zones to smooth the transition from the original road surface to the full thickness zone.

The process required two trucks and a four person crew to complete the work in four days. All the work was performed in one traffic lane at a time while keeping the other lane open for traffic. Because of the poor road surface before the injection, the surface was milled at a later time. The subsequent road surface was sufficiently leveled to make the mediation unnoticeable.

Injection and Instrumentation Locations

  • Thirty survey points at 10 feet centers were measured over a 300 foot distance on five rows located at:
    • The centerline of the road,
    • The centers of the two lanes, and
    • The north and south edges of the lanes.
  • Five piezometers located in the north and south shoulders of the road.
  • Six boreholes with thermistors to measure the temperatures in the soil profile. One thermistor in each hole was located:
    • Above the injection point and the foam layer,
    • Below the foam layer, and
    • Ten inches below the foam.
    • One or two other thermistors were located lower depending on the depth to bedrock.

Results

The upper figure shows the measured elevation changes from the summer baseline along the center of the east bound lane.

    • The thin solid black line shows the heave in January prior to the injection of the foam. The dip at STA 2+10 is the location of a French drain that was backfilled with non-heaving sand.

 

    • The heavy black line shows the foam thickness averaging 3 inches with tapered edges to the east (STA 2+40 to 2+70) and west (STA 1+70 to 1+40).

 

    • The colored lines show the elevation differences in the two winters after injection. The total heave over the treated zone is generally less than 0.5 inches and is less than the natural heave outside the treated zone. The lower figure

 

    • shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

 

 

The upper figure shows the measured elevation changes from the summer baseline along the center of the east bound lane.

  • The thin solid black line shows the heave in January prior to the injection of the foam. The dip at STA 2+10 is the location of a French drain that was backfilled with non-heaving sand.
  • The heavy black line shows the foam thickness averaging 3 inches with tapered edges to the east (STA 2+40 to 2+70) and west (STA 1+70 to 1+40).
  • The colored lines show the elevation differences in the two winters after injection. The total heave over the treated zone is generally less than 0.5 inches and is less than the natural heave outside the treated zone. The lower figure
  • shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

The lower figure shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

This figure shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

The heavy black line in the below graph shows the thickness of the foam being about 3 inches under the east bound lane and tapering to zero under the west bound lane.

  • The thin colored line is the measured heave in the year before construction.
  • The other colored lines are the measured heaves during the two winters after construction.
  • The heave on the south edge (-12 feet) is caused by edge effects and local freezing.
The heavy black line in this graph shows the thickness of the foam being about 3 inches under the east bound lane and tapering to zero under the west bound lane. The thin colored line is the measured heave in the year before construction. The other colored lines are the measured heaves during the two winters after construction. The heave on the south edge (-12 feet) is caused by edge effects and local freezing.

Conclusions

  • Transferability of the control strategy is possible if the weather conditions in the new corridor are similar (i.e. defined by the same weather variables) to the corridor where the control strategy was developed.
  • It would be beneficial to train the decision trees with the storm data collected at the new corridor.
  • The system should be monitored till it is recommending desirable speed limits based on real time weather and traffic information.
  • From the simulation results it is observed that proposed control strategy is performing slightly better than WYDOT’s manual protocol.
  • If the control strategy is to transfer a completely new corridor, it would be ideal to collect some storm data and train the decision trees before using the control strategy in real time.