Deere & Ault Consultants, Inc. - Dam & Reservoir Projects

• Brannan No. 29
• South Platte Reservoir
• Stagecoach Reservoir
• Cat Reservoir
• Chase Gulch Dam
• Design Build Slurry Walls for Gravel Pit Reservoirs
• Dunes Reservoir
• Fort Lupton Pit
• Kyger Pit
• Shores Project
• Siebring Reservoir

Brannan #29
Adams County, Colorado

Soil-bentonite slurry wall being excavated with a long-stick trackhoe.

Brannan #29 is currently an active aggregate mine located near the town of Henderson, Colorado, in Adams County. The mine will be reclaimed as a water storage reservoir when mining is complete. D&A staff designed the soil-bentonite slurry wall liner which was installed in 2003. Approximately 14000 LF of slurry wall to a maximum depth of almost 70 feet was constructed around the site. An intermediate slurry wall dividing the site was also built. A water right has been filed for 8500 acre-feet on this site.

Engineering services included geotechnical investigation with soil and bedrock sampling and testing. Engineering services provided include: geotechnical investigation with soil and bedrock sampling and testing, field permeability testing of the bedrock, slope stability and seepage analysis, development of construction drawings, development of technical specifications, and construction related engineering services. Currently D&A staff is developing a leakage testing program for the storage decree. This work is currently being coordinated with the Colorado Division of Minerals and Geology and Colorado State Engineer's Office - Division 1.

Client: United Water and Sanitation District
Project Cost: $2.5 million

Overview of the reservoir site and
dam embankment.

Earthen borrow, haul, and placement circuit in southwest corner of reservoir site.

South Platte Reservoir is located north of Chatfield Reservoir in Arapahoe and Jefferson Counties, Colorado. It is adjacent to several residential subdivisions and a popular greenbelt park along the South Platte River. The site is currently being transformed from a working gravel mine into a municipal raw water storage reservoir for Centennial Water and Sanitation District.

An evaluation was made of the feasibility of constructing a 6,200 acre-foot reservoir. A complete geotechnical engineering, civil engineering, and environmental investigation were performed. Upon completion of the investigations, the project moved forward with the design of the reservoir, preparation of plans and specifications, and permit acquisition assistance with local and state agencies. We are currently providing resident engineering services during embankment construction. In addition, the project includes several ancillary components for the reservoir; including 3,000 lineal feet of 48-inch diameter steel pipe and a 60 cfs pump station and 700 feet of interceptor drain to control the outside groundwater table.

Major project components included a 70-foot high zoned earth embankment with 3.2 million cubic yards of earthwork, a Probable Maximum Flood by-pass channel with drop structures, a multi-leveled outlet works, and two acres of wetlands. The PMF channel is approximately 100 feet wide and will convey up to 23,000 cfs.

Client: Centennial Water and Sanitation District
Project Cost : $26 million

Test pit work for soil investigation at Stagecoach Reservoir.

The Stagecoach site is a future gravel mine located near Henderson, Colorado, in Adams County. The mine will be reclaimed as a water storage reservoir when mining is complete. The reservoir liner was designed as a soil-bentonite slurry wall approximately 7,000 feet long. D&A staff is currently providing construction related engineering services while the slurry wall is being constructed.

Other Engineering services provided include: geotechnical investigation with soil and bedrock sampling and testing, field permeability testing of the bedrock, borrow investigation studies, slope stability and seepage analysis, development of construction drawings, development of technical specifications, and construction related engineering services.

Client: Lafarge West, Inc.
Project Cost: $1 million

Initial compacted embankment slope liner construction along the mine highwall.

Cat Reservoir is a below grade, lined, water storage reservoir being constructed in conjunction with aggregate mining activities. It is a design build project and is located near the confluence of Clear Creek and the South Platte River in Adams County, Colorado. The reservoir liner is a 7700 feet long compacted earthen embankment slope liner constructed from on-site soils. Design challenges include coordinating the aggregate mining\highwall design and reservoir construction along existing utilities, including a 42” diameter PCCP force sewer main. Highwall and compacted embankment slope liner stability challenges were compounded by the presence of a relatively thick and soft mud lens.

The site is underlain by fractured permeable claystone bedrock. Under D&A guidance and to help minimize the project construction costs the liner is being constructed in two phases using an observational approach. Infiltration rates will be measured after Phase I is complete. Once completed and, if required, remaining local seepage areas will be sealed during Phase II in order to pass the state seepage criteria.

Final reservoir storage volume is projected to be approximately 2,500 acre-feet.

Client: Cat Construction and Denver Water Board
Project Cost : $1.6 million

Chase Gulch Dam
Central City, Colorado

Chase Gulch Dam is a 100-foot high concrete faced rockfill dam.
The photo illustrates rockfill placement and initial construction of the face slabs.

D&A staff provided complete engineering, design, and construction engineering services for a concrete-faced rockfill dam in the mineral belt area of the Colorado Front Range near Central City, Colorado.

The dam site is at an elevation of approximately 8,700 feet. The dam impounds water on Chase Gulch, a tributary to North Clear Creek. Preliminary designs were prepared for both a concrete-faced rockfill dam and a roller-compacted concrete dam. The concrete faced rockfill embankment dam was selected as the most suitable for the site conditions and available construction materials.

Dam design was completed in the fall of 1992. Construction began in February 1995, and was completed in December 1995. The dam consists of a 100-foot high, quarried, rockfill embankment with upstream slopes of 1.4:1 (horizontal to vertical) and downstream slopes of 1.3:1 with a crest width of 25 feet. A concrete toe plinth and upstream concrete face provided the water barrier. A foundation grout curtain constructed through the toe plinth intercepts potential under-seepage. Appurtenant structures included:

•   A 30-inch diameter outlet pipe through the rock foundation with an upstream guard gate
    and downstream valve

•   A pump station to convey raw water from the dam to the water treatment plant

• A chute-type spillway excavated in the rock around the left dam abutment to pass flood flows

Client: City of Central
Project Cost: $5.2 million

Design Build Slurry Walls for Gravel Pit Reservoirs

Soil-bentonite slurry wall constructed
with a long-stick excavator.

The Siebring Reservoir constructed in 1991 was the First gravel pit reservoir in the state of Colorado to be lined with a slurry wall.

Deere and Ault Consultants, Inc. (D&A) is the leader in design-build of slurry walls for gravel pit reservoir projects. Our group of professional engineers has designed more of these facilities in the State of Colorado than all other firms combined. Our engineers have the experience to focus our investigations and design efforts on the site factors important for constructing successful slurry wall reservoirs. Our designs incorporate the site specific soil and bedrock conditions to develop appropriate key trench depths in the bedrock and practical backfill mixes considering available borrow soils.

A list of our projects currently in design or construction are:

•   Shores Reservoirs A, B, C, and D
•   Heit Pit
•   Nissen Pit
•   Bernhardt Reservoirs
•   Walker Reservoir
•   Stagecoach Reservoir
•   Stagecoach North
•   Fort Lupton Reservoir
•   Hill-Eber-Oakley Pit
•   Golden Pit Reservoir

Dunes Reservoir
Brighton, Colorado

Riprap slope protection and riprap bedding placement along upstream face of dam embankment.

Earthen dam construction activities, building upward from reservoir bottom.

The Dunes Reservoir is a 5,200 acre-foot project located northwest of Denver, Colorado. The project includes one million cubic yards of earth dam construction, a concrete emergency spillway, and a 48-inch diameter outlet pipe. Deere and Ault Consultants, Inc. (D&A) provided final design services and construction engineering for the project.

The water storage reservoir will be owned by the Denver Water Board and South Adams County Water and Sanitation District. Project challenges include coordination between embankment dam construction and on-going mining activities, special design consideration and design amendments during construction were required to use available on-site borrow materials for embankment dam fill, and coordination to accommodate an existing large capacity canal running parallel to the downstream toe of the dam.

Client: Dunes Investment Partners, LLC Denver Water
Project Cost : $8 million

Fort Lupton Pit, Golden Site and Hill/Eber/Oakley Site
Fort Lupton, Colorado

Kamatsu PC 750 long-reach excavator digging slurry wall on the Golden site

This is a design/build project with Compass Environmental for two below grade gravel pit water storage reservoirs with perimeter soil-bentonite slurry wall liners. The project site is near Fort Lupton, Colorado. D&A is providing investigation, analysis, and design, as well as quality control during construction for the 3,700 linear foot Golden Site slurry wall and the 5,300 linear foot Hall/Eber/Oakley slurry wall.

The Golden Site slurry wall is presently under construction. Construction on the adjacent Hill/Eber/Oakley site is planned for later this year.

Client: L.G. Everist
Project Cost: $160,000

Kyger Pit Reservoir
Windsor, Colorado

Typical earthen embankment slope liner construction
similar to that planned for the Kyger Pit Reservoir.

The Kyger Pit is currently an active aggregate mine located near the town of Windsor, Colorado. The mine will be reclaimed as a water storage reservoir when mining is complete. D&A is in the process of developing a reservoir lining system for the site. The liner will consist of a low permeability earthen slope liner embankment.

This slope liner will be constructed against the mine highwall and will extend from the claystone mine floor up to the existing ground surface. Approximately 8,000 linear feet of slope liner will be constructed. Engineering services provided include: geotechnical investigation with soil and bedrock sampling and testing, field permeability testing of the bedrock, borrow investigation studies, slope stability and seepage analysis, development of construction drawings, development of technical specifications, and construction related engineering services. Regulatory agency coordination includes the Colorado Division of Minerals and Geology and Colorado State Engineer's Office - Division 1.

Client: Lafarge West, Inc.
Project Cost: $1 million

The Shores
Longmont, Colorado

Soil-bentonite slurry wall reservoir liner system under construction.

The Shores Reservoirs are below grade, lined, water storage reservoirs constructed in conjunction with aggregate mining activities. The site is located near the St. Vrain River in Weld County, Colorado. Reservoir liners include compacted earthen embankment slope liners and soil-bentonite slurry wall lining systems. In total, over 25,000 linear feet of liner will be constructed. Design challenges include coordinating the reservoir construction with existing irrigation ditch facilities. Eight existing ditches and irrigation laterals crossed the property. Relocation of ditch diversion structures, design and construction of new laterals and diversions to fill the ponds, and configuration of the reservoir layouts required careful consideration and coordination with ditch company boards and individual lateral owners.

Federal permits, including U.S. Army Corps of Engineers' 404 permits were required. New diversions to fill the reservoirs and interconnecting pipeline tunnels between the reservoirs were designed.

Final reservoir storage along with the filling and interconnect facilities will be owned by Central Colorado Water Conservancy District. The projected total water storage volume will be approximately 4,800 acre-feet.

Client: Lot Holding, LLC
Project Cost : $2 million

Siebring Reservoir
Greeley, Colorado

Siebring Reservoir was lined with a 12,106-foot long soil-bentonite slurry
wall converting a mined gravel pit into a raw water storage reservoir.

The Siebring Reservoir, constructed in 1991, was the first gravel pit reservoir in the State of Colorado to be lined with a slurry wall. The project was designed by D&A personnel and constructed by Hall-Irwin Construction.

The site is located along the Cache la Poudre River just west of Greeley, Colorado. The slurry wall has a total length of 12,106 feet. The slurry wall was constructed during gravel mining operations. After completion of the wall, dewatering requirements ceased.

The total storage is 1,214 acre-feet, of which 84 acre-feet are stored in the void space. The storage rights were purchased by Central Colorado Water Conservancy District.

Client: Central Colorado Water Conservancy District
Project Cost: $450,000