Hall-Irwin has developed the first United States Slurry Wall for the purpose of water retention. A bentonite-clay slurry mixture that surrounds bodies of water all the way down to bedrock keeps groundwater from entering the body of water. It also keeps the water within the lining from leaking out. This helps record the correct amount of water loss which is required by the government.
"A state law passed in 1977 put an end to the practice of abandoning spent gravel pits by requiring reclamation of mining sites," said Tony Waldron, mineral program manager with the Colorado Division of Reclamation, Mining, and Safety.
Hall-Irwin has been successfully contributing to the solution of Colorado's water storage issues by designing and building clay-bentonite slurry lines for over 30 years. To this day, Hall-Irwin has successfully passed all state-required leak tests.
Contact us to learn more about how a slurry wall might solve your issue.
Hall-Irwin Corporation brings historical knowledge to the City of Greeley’s Poudre Pond project in 2020 as Colorado’s premier design-build/assist team of soil bentonite cutoff walls and water storage systems. Having constructed Pond A cement soil bentonite cutoff wall and then through mining, construction, and some reclamation at the current site; Hall-Irwin is in a unique position to help the City of Greeley evaluate all aspects of the Poudre Ponds’ master plan for a successful cement soil bentonite cutoff wall and partnership. Project features include 240,000 square feet of soil bentonite cutoff wall, a 36” interconnect between Pond A and Pond B through an existing cement soil bentonite cutoff wall (constructed by Hall-Irwin in 2002) and a rundown structure to protect the cement soil bentonite cutoff wall from Poudre River flood events. Part of Hall-Irwin’s mission is to bring a balance between high standards of design, value, and constructability to meet the overall project goals. Completed December of 2020.
Holton Lakes Mine - Slurry Wall
This project started as an engineering design and became a physical project the following year. The project included installing a slurry wall around the perimeter of the Stage 4 Gravel Pit on the Holton Lakes Mine property estimated at 222,768 square feet. Our work involved survey, quality control and leak tests; excavation and backfill; and grading.
Geisert - Gravel Pit Slurry Wall & Pump Station
Geisert Gravel pit was partially mined by Weld County who was losing money because the pit was filling up with water which meant they were constantly spending time and money dewatering. So, to avoid the cost of augmentation and continual dewatering, Weld County decided to construct a cutoff wall (slurry wall) around the two mining pits. Hall-Irwin was selected to lead the design-build team to construct a cutoff wall that is approximately 7200 LF long with an average depth of 68 ft. This is one of the deepest walls in Colorado with the greatest depth reaching 76.5 ft to the bottom of the key. To dig to this great depth, we used a Komatsu 1250 with a custom fabricated stick that was 60 feet long.
The Shores - Slurry Wall, Pond D Flood Repair & Interconnect
This was a design-build water storage project with five separate gravel pits: Shores Ponds A, B, C, D & E. Ponds B, C, & D have individual soil-bentonite cutoff walls (slurry walls) constructed around each gravel pit, all of which have passed the State of Colorado Certified Leak Test. Pond A has a combination of a clay liner and a cutoff wall that ties into the clay liner. This wall has also passed the State of Colorado Certified Leak Test. After mining was completed on Pond E, Hall-Irwin constructed a clay liner utilizing the bottom shale, which also passed the State of Colorado Certified Leak Test.
The five ponds (A,B,C, D & E) work in conjunction with each other through a series of interconnects, inlet structures (to divert water via two separate irrigation canals), and a pump station in Pond A. All of this allows for the largest amount of water conveyance both in and out of the reservoirs. The cut-off walls that surround these four below-grade reservoirs total 23,150 LF. The soil-bentonite cutoff wall backfill was keyed into bedrock with a maximum depth of 32 FT creating approximately 4,500 acre feet of water storage.
The Shores Reservoir Pond D was damaged due to flooding. The repair to the reservoir required rebuilding two slurry wall sections that were breached, each approximately 200 LF. This required us to tie into the existing soil-bentonite cutoff wall (slurry wall) at four locations. Additionally, the project included reconstructing the roadway (approximately 1,985 LF), repairing roughly 2,775 LF of the Godding Ditch, dewatering, and removal of 70,000 CY of silt.
The Interconnect was a design-build water storage project connecting the five separate gravel pits, each with individual slurry walls.
HWY 34 - 100 Year Flood Repair
After the destruction of the 2013 floods in the Thompson River Canyon—the most significant flood since 1976—the Colorado Department of Transportation worked hard to reconstruct Colorado Hwy 34 in a manner that would allow it to withstand future flood events of the same magnitude. Hall-Irwin was hired as a subcontractor for Kiewit Infrastructure to help build a section of The Narrows, to complete permanent highway repairs using our slurry wall methods. These permanent repairs involved excavating the inside lane of traffic from surface to bedrock, mixing the excavated soil and rock with cement, and placing those materials back in the excavated trench. Throughout this project, our team worked under a very aggressive 7-day, double-shift schedule, within confined spaces, and without the use of normal cellular connectivity. The confined space and remote location required us to put together a high-efficiency work plan to facilitate logistics, including fuel and cement deliveries. The outer lane of traffic remained in continuous public use, in accordance with CDOT’s public access requirements, providing our team with only a single lane of traffic next to the canyon wall in which to conduct operations. Some sections of the road required us to first build a slurry wall to maintain the stability of the outer lane before we could begin rebuilding the inner lane. In addition, we were expected to preserve and protect both the canyon wall and the adjacent Bid Thompson River, which we achieved. We also were tasked with aggressive mobilization and de-mobilization schedules. Although the working conditions were strenuous and unconventional, by the completion of our work, we had met the owner’s expectations, and stayed within budget and on schedule.
Hall-Irwin has had a long-standing relationship with both the Bernhardt farm and CCWCD. More recently, this partnership resulted in a contract to complete the construction of the Bernhardt retention pond, including leak tests for their previously installed slurry wall, a riprap rundown to facilitate river overflow, and a custom grade beam to measure water levels. We also installed a micro-pool at the base of the rundown to absorb water when the pool runs low. We always enjoy working with repeat clients as we help develop the land along the beautiful Front Range.
O Street Slurry Wall
Orlando, LLC contracted with Hall-Irwin for this Design-Build project, which resulted in a 4,000-foot long slurry wall at an average 45-foot depth. During the design process, our team helped the owners analyze whether the construction of this wall would be profitable in the long term. After deciding in the affirmative, Orlando, LLC enlisted the help of Hall-Irwin in the entitlement process before construction could begin. Additionally, we advised that the owners redesign the wall to sit right on the property line, rather than inside of it, which would benefit them with more capacity, and benefit their neighbors, who could then simply tie into the wall. These hurdles successfully navigated, we proceeded with building what is now a fully leak-proof slurry wall which will be useful to store water for years to come.
Timnath Slurry Wall
In 2021, the State of Colorado got in touch with the Town of Timnath to inform them that groundwater had been observed seeping into the bottom of one of their detention ponds. As they were required to remedy this situation immediately, Timnath, through their management company Catalyst, contacted Hall-Irwin for help. We gladly stepped in and sealed off the detention pond for them. Additionally, the Town wanted an augmentation pond installed, to make way for the future Timnath Landing subdivision. Hall-Irwin agreed to install a slurry wall around this pond and seal it off down to bedrock. We helped value-engineer the project for them, and used cement-stabilized soil bentonite for the wall. The soil around the slurry wall turned out not to be stable enough to support the heavy equipment necessary to construct a slurry wall, so large crane mats were used throughout the project. In the end, a successful augmentation pond was made possible by our team, and the owner was satisfied with our work.
Milliken Slurry Wall
Hall-Irwin was contracted by Scout Investments and the United Water District to install a slurry wall for this new reservoir within Martin Marrietta Materials’ (MMM) mining site near Milliken. Once the slurry wall is complete and a leak test shows that water is no longer infiltrating the site, Scout Investments will lease the area to MMM, who will mine out the good material. The pond will be filled for future water storage purposes after the site is mined to the approved water retention volume. Our team encountered several hurdles to overcome in the construction of this project, including a dense area of both underground and above-ground utility lines in the south corner, requiring a complex crossing plan and constant coordination with utility providers to protect their lines while allowing for the slurry wall’s construction. Throughout construction, Hall-Irwin ensured MMM’s mining operation could continue uninterrupted, including the use of their conveyor belt, which ran along the full length of the site’s west edge. Early on, we hit very hard bedrock at an elevation higher than expected, so we created an alternative excavation method to deal with this early refusal, which would have inhibited proper slurry wall construction. Once complete, this will be a useful storage site for the owners for years to come.