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By applying unique solutions to increase the safety and longevity of our environment.

HRSD 24″ Forcemain Abandonment

The Job

HRSD’s Virginia Beach Boulevard Forcemain Replacement project installed more than a mile of new pipe to replace an aging 24″ forcemain.

As part of decommissioning the original forcemain, it needed to be filled completely with grout.

The Challenge

Due to extensive widening of the roadway the pipe was originally constructed alongside, extensive commercial and residential development, the number of access points needed to be as few as possible. This was driven by extensive structures over/adjacent to the old pipe, and a desire to reduce disruptions to adjacent stakeholders, and the risk of any utility strikes during access pit excavation.

The Solution

CJGeo grouted more than 7,000LF of the 24″ pipe over a period of a four working days onsite. The pipe was completely filled, which was verified by uniform material venting from the far end of each run. Run lengths ranged from 450LF to more than 2000LF.

DeRuyter Reservoir Outfall Abandonment

The Job

The DeRuyter Reservoir, in DeRuyter, New York, is a 557 reservoir originally developed as part of the Erie Canal system.

As part of a dam upgrade project, the three parallel 22″ diameter, 300LF outfall pipes needed to be abandoned, along with a stone box culvert downstream of the valve chamber the pipes terminated into.

The Challenge

Each of the three pipes had been previously blind flanged by divers. Therefore, the only access was from the downstream end within the valve chamber. In order to vent the air displaced by the abandonment grout, vent or placement points needed to be installed just behind the upstream blind flanges, which were approximately 40′ below the water surface.

The Solution

CJGeo worked with the general contractor to design an internal venting system utilizing sacrificial placement pipes installed from the valve chamber. After each of the sacrificial grout pipes was installed, the downstream terminations were bulkheaded, with vent stubs.

CJGeo mobilized a cellular grouting crew, who placed 30lb/cuft cellular concrete through each of the sacrificial grout pipes, until grout returned to the bulkhead vents, confirming fill. The work was completed over two days onsite–the first day for the abandonment pipes and first lift in the box culvert, and the second day for a top off pour on the box culvert.

250000 Gallon Oil Tank Abandonment

The Job

As part of decommissioning an underground oil tank at an institutional facility in Washington, DC, it needed to be filled with excavatable material that was lighter than the roughly 55lb/cuft heating oil it was designed to hold.

The tank is located in a small empty lot, which is slated for redevelopment in approximately three years.

The Challenge

To be officially considered decommissioned, the tank had to be completely filled. It is slated for removal as part of the redevelopment process of the area (it sits within a future basement excavation) so the fill material had to be excavatable.

The Solution

CJGeo proposed 20lb/cuft cellular concrete for the abandonment grouting. This afforded plenty of factor of safety to reduce the likelihood of settlement induced by filling the tank, and maximized excavatability

CJGeo placed the fill material over a period of two days onsite. Because cellular grout is highly mobile, no entry was required during the placement of the fill material, which designed a significant amount of risk out of the process.

The 1200CY placement was performed over two days onsite.

Retaining Wall Lightweight Backfill

The Job

Sanitary sewer right of ways straddling lot lines can be particularly troublesome if a problem occurs with a line and trenchless repairs aren’t possible. This was the case on an 8″ gravity line in Arlington, Virginia. Extensive structural damage to the line caused repeated backups and raised stability concerns for multiple retaining walls which had been constructed over the line.

The walls ranged from four to eight feet tall, and were a mix of concrete and natural stone.

The Challenge

Timber-shored, hand-excavated work was done on the high side of the wall to expose and replace the affected lines. Because of stability concerns with the walls, the geotechnical engineer specified material no heavier than 25lbs/cuft.

The only access was pumping material from the street, down a decorative flagstone pathway between two homes, and into the excavated pits.

The Solution

CJGeo proposed 25lb/cuft wet cast density permeable cellular concrete for the backfill material. Because there is no aggregate, it can easily be pumped through small diameter lines at low pressure, which addressed the accessibility concerns.

Because the material is permeable (modified ASTM D-2434 2.0cm/sec), it is freely draining and reduces hydrostatic loads on adjacent structures.

CJGeo mobilized twice for the phased project, and backfilled each of the pits in a single lift.

Fire Station Floor Lifting

The Job

The concrete slab on grade floor inside of a fire station on the North Neck of Virginia settled up to two inches. As part of the investigation into the cause, an engineer discovered voids up to 8″ below the slab, and multiple broken sanitary sewer pipes below the floor.

The affected areas included a dayroom, kitchen & meeting hall.

The Challenge

In order to minimize disruption to the fire station’s operations, the proposed repair had to be quick, clean, and minimize uncertainty associated with the plumbing repair slab cuts.

The Solution

CJGeo performed ground improvement grouting of the underlying soils to 5′ below grade utilizing plural component polyurethane compaction grouting. Shallow voids were filled using plural component polyurethane, which was also used for settlement correction.

Because polyurethane grouts cure very quickly, the floor was repaired the day before the plumbing work was scheduled. This allowed the plumbers a stable work surface, and eliminated the risk of stuck saws or sudden collapse of the floor during floor sawing for plumbing access.

Pre & post grouting DCP testing was done to verify grout travel.

NY Thruway HDD Annular Space Grouting

The Job

As part of distribution improvements, National Grid’s contractor bored 830LF through rock using HDD. The bore was 30″, with a 16″ HDPE casing, carrying three, 4″ HDPE conduits.

As part of the installation, the NY Thruway Authority required the casing be backgrouted, and the casing pipe’s annular space grout filled.

The Challenge

The proposed backgrout had to be pumpable 830LF at very low pressure, dense enough to displace the 10PPG drilling mud, and provide sufficient strength to meet Thruway requirements. The proposed annular space grout had to be pumpable 830LF at very low pressure, light enough to not apply excessive pressure on the conduit pipes, and also provide sufficient strength to meet Thruway requirements.

The Solution

CJGeo proposed two different grout mixes to meet the project requirements. 85lb/cuft casing backgrout for displacement of the 10PPG (75lb/cuft) drilling mud, and 25lb/cuft annular space grout for within the casing.

CJGeo’s crew mobilized to the site, and successfully performed the backgrouting and annular space grouting in a single day.

8″ Toe Drain Abandonment

The Job

Lake Whetstone is an approximately 30 acre manmade impoundment located in Montgomery Village, Maryland. It is utilized for stormwater runoff control, and also recreation, with an approximately 1000LF earthen dam.

As part of a retrofit program of the embankment, two 8″, perforated CMP toe drain pipes needed to be grouted for a minimum of 100LF, under active flow.

The Challenge

Each of the two, 100′ long pipes needed to be grouted full, but could only be access from the downstream end of the pipes. One pipe had nominal flow, and the second pipe had approximately 10GPM, and discharged through an end wall structure at the stilling basin.

The Solution

The project designer, Gannett Fleming, specified NSF Section 61 certified grout (potable water contact) for the abandonment grout. Due to “one shot” nature of the project, above ground mockups, including sacrificial pipe installation, chemical grout cup testing, yield analysis and visual inspection, were all required prior to the start of grouting.

CJGeo performed the onsite mockup testing and analysis, and then grouted the two pipes in place successfully over a period of two days onsite.

5520CY Tank Abandonment

The Job

As part of a water treatment plant rehabilitation project in Stamford, Connecticut, a 25,000sqft underground tank needed to be abandoned, and the concrete roof removed.

The geotechnical engineer required an average fill density less than 60lbs/cuft to avoid settlement.

The Challenge

The lightweight fill material had to to provide sufficient support for approximately 4′ of compacted fill material, and a delivery truck loading dock and future building.

The Solution

CJGeo proposed 25lb/cuft permeable cellular concrete with an approximately 10ksf compressive strength to fill the structure.

CJGeo placed the 25lb/cuft cellular concrete in daily pours up to 980CY, in single lifts up to 36 inches thick. The roof demolition debris dropped onto the top of the cellular concrete and was then buried with fill material.

The total project volume was approximately 5520CY.

Corporate HQ Stabilization

The Job

Starting immediately after construction was completed, the slab on grade floor within the cafeteria, loading dock and kitchen at a corporate headquarters building in Pittsburgh, Pennsylvania settled. Over the course of 12 years, the owner had four different grouting companies attempt to address the problem. Lime slurry injection below the slab was disruptive, and settlement always resumed shortly thereafter.

Compaction grouting was performed in one area, but was so disruptive that despite the fact that it was the only method where settlement didn’t resume, the owner kicked the contractor off the site after nearly four months of not having access to their executive dining room.

The Challenge

Settlement progressed over time to be as much as four inches, affecting nearly 20,000 square feet of floor. A general contractor retained by the owner reached out to CJGeo about performing low impact grouting to address the settlement.

Because settlement affected the entire kitchen, food prep, serving and majority of the dining areas, repairs had to be facilitate continuous use of the facility. Additionally, due to 24 hour staffing of the facility, noise had to be limited, and there was zero tolerance of dust.

Video inspection of the extensive gravity sanitary and floor drains below the floor revealed six defects, including a 2″ offset in a sanitary drain line for a 6 stall restroom.

The Solution

CJGeo performed 17 DCP tests to determine the depth of uncontrolled fill, which was the presumed cause of settlement. DCP testing showed pockets of WOH fill down to 35′ below finish floor, and voids ranging from 2″ to 18″ immediately below the floor.

Over the course of 7 nights onsite, CJGeo crews installed 12,000 pounds of CJGrout 20SDB into voids immediately below the floor, and 53,000 pounds of CJGrout 35NHV61 for polyurethane compaction grouting. Compaction grouting was performed up to 35′ deep, but to an average depth of 15′ over the entire area.

All work was completed off hours. As soon as the kitchen shut down for the evening, CJGeo crews swung into action, grouting through the night until wrapping up in time for the food prep crews to get ready for breakfast at 0500.

To facilitate grouting under four walk-in freezers and refrigerators, over the course of a 24 hour shift, all cold contents were moved to reefer trailers, CJGeo grouted to 30′ under the freezers and refrigerators, which were then immediately turned back on, and then refilled.

Through careful coordination with multiple operational divisions for the owner, general contractor, flooring restoration contractors, plumbers, and remediation contractors, CJGeo successfully completed the project under budget and on time.

Bulkhead Sinkhole Grouting

The Job

With an annual throughput capacity of 48 million tons, Norfolk Southern’s Pier 6 at Lamberts Point in Norfolk, Virginia is one of the largest coal transloading facilities in the world.  As a round-the-clock facility built around precision logistics, there’s little tolerance for disruption or downtime.

The Challenge

 When two sinkholes opened up at the end of Pier 6 adjacent to the bulkhead, railroad personnel reached out to an onsite maintenance contractor.  Steel plates were installed to provide temporary protection while a long term solution could be implemented.

The Solution

CJGeo performed DCP testing at the site in order to quantify the depth of voids below the pavement adjacent to the sinkholes.  The DCP testing showed that in addition to large voids visible from the sinkholes immediately below the pavement, there were large pockets of voids down to 15’ below the surface. 

CJGeo crews then used CJGrout 35NHV61, a hydroinsensitive, NSF-certified geotechnical polyurethane to fill all voids and restore stability to the area. The grouting work took five hours onsite to install 3400 pounds of material, with zero disruption to operations.

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