City and County of Broomfield Water Conservation Plan - Broomfield, Colorado

In 2004, the Colorado Water Conservation Board (CWCB) passed Colorado’s Water Conservation Act of 2004, which requires all retail water providers who sell at least 2,000 acre-feet of water annually to develop and gain CWCB approval of a Water Conservation Plan. As of July 1, 2005, the minimum Water Conservation Plan requirement elements were defined by the CWCB in §37-60-126(4) C.R.S.

Beginning in 2008, LRE staff worked with the City and County of Broomfield (Broomfield) to develop a Water Conservation Plan to help Broomfield more efficiently use their water supply. LRE prepared a successful CWCB grant application for the conservation plan.  LRE followed the CWCB guidelines to draft a Water Conservation Plan fulfilling the State requirements.

Using information provided by Broomfield, LRE profiled the existing water system including a description of water sources and their limitations, water costs, policies, guidelines, and current water conservation activities. This enabled us to define current water use and demands, as well as forecast future demands based on population projections. Based on the forecasted demands, proposed infrastructure improvements were identified by Broomfield, and anticipated costs for these system improvements were determined.

With input from Broomfield staff, a list of conservation goals was drafted. These goals led to targeting specific areas where conservation would be most successful and is most needed. A preliminary list of potential conservation programs and measures, including those required by CWCB, was developed by Broomfield and LRE staff. Using screening criteria developed with input from Broomfield staff, the universe of options was narrowed to a smaller secondary list.

We next evaluated and selected conservation measures and programs for further consideration by Broomfield. Different combinations of measures and programs were evaluated to focus only on the most effective programs to operate within Broomfield’s system. Conservation options were compared based upon potential water savings and costs. Additional evaluation criteria were introduced and a final list of selected programs and measures was developed.  After final selection of conservation programs and measures, a new 10-year demand forecast was calculated that determined the potential savings resulting from conservation initiatives.

Finally, an implementation schedule was developed by Broomfield staff with assistance from LRE based on the timing and cost of selected conservation programs and measures. Details regarding public participation, monitoring of programs, evaluation, updating, and revising of the conservation plan were described and will allow Broomfield to move forward with conservation activities and bring to action this conservation plan. 

Pine River Canal Emergency Repair - La Plata County, Colorado

The Pine River Canal supplies irrigation water to approximately 20,000 acres of private and tribal farmlands. In the winter of 2009/2010, the Tribe contacted LRE about a potential failure to a section of this canal. The section carries 300 cubic feet per second of water and is located approximately four miles south of the Town of Bayfield, CO. In this area, the canal runs adjacent to Beaver Creek, and due to years of erosion in both Beaver Creek and the canal, the embankment that separates them had decreased from hundreds of feet to about 20 feet. It was suspected that the embankment would fail during the spring high flows, and a failure would result in loss of irrigation water to farmland and possibly cause flooding and property damage along Beaver Creek. 

In early 2010, LRE developed three alternative solutions to repair the canal. From these solutions, the Tribe selected one, and LRE developed preliminary design drawings and a budget. By the time the Tribe secured funds for the repair, the canal was within a month of being placed into service after its normal winter shut-down. The Tribe contacted LRE to proceed with the repair’s final design and construction, but at this point there was one critical factor in the project; both had to be completed within 30 days. 

LRE immediately mobilized a response team to finalize the design and coordinate the construction efforts. A geotechnical engineer and contractor were added to the response team within a few days. The preliminary evaluation revealed that prefabricated interlocking concrete blocks would be the most effective method to stabilize the canal’s banks. The blocks were placed in large sheets shortening installation time. A block manufacturer was found that could deliver the blocks within the limited time available. 

Following the design, LRE staff was on site to monitor the construction process, verify proper installation, coordinate with the geotechnical engineer, keep the project within budget and on schedule, and respond to any situations. Construction of the repairs was completed in eight days. From the initial contact to the acceptance of the block installation, the project took 29 days to complete, and Pine River Canal was put into service on time. For further information, contact wayne.eckas@LREwater.com.

Evaluation of Ground Water Supply and Subsidence 

Project Goal:  Evaluation of ground water for an industrial water supply in an arid basin subject to subsidence caused by fluid withdrawal.

Project Highlights:

• Use of USGS MODFLOW program
• Initial basin-scale model quickly prepared with very little available data
• Automated model calibration using PEST and parallel processing
• Model predictive uncertainty analysis
• Aquifer test design and interpretation
• Evaluation of geophysical logging techniques in existing wells
• Cost/benefit tool development for ranking of field investigation tasks
• Subsidence empirical relationship research
• Subsidence modeling using the SUB-WT package
• Testing of one versus three-dimensional subsidence modeling

LRE recently completed the initial phases of a ground water supply feasibility project for an industrial user located in the arid southwest. We evaluated ground water as a supply of over 10,000 acre feet per year in an area that is subject to land subsidence.

In 2009, LRE performed ground water modeling to evaluate preliminary project feasibility for a ground water supply.  We created a regional MODFLOW ground water model with very little available data and within a short time frame. The model results confirmed ground water as a viable water supply for over 60 years. LRE used the model results to scope future field investigation and modeling work. Also during this phase, we identified subsidence due to fluid withdrawal as a threat to the project viability.

In 2010, LRE continued to move the project forward by completing additional ground water modeling, field data collection, and subsidence predictions integrated with the MODFLOW ground water model results. We designed and interpreted three 72-hour aquifer tests using existing irrigation wells. LRE's aquifer test interpretation included water level and barometric pressure data from data loggers in six wells. We used these data with new lithologic and geophysical data to update the MODFLOW water supply model. LRE re-calibrated the model using PEST automated calibration and parallel processing. We then recalibrated the model and evaluated well field yield at various locations.

LRE investigated subsidence risks by collecting available data and evaluating various subsidence empirical relationships that could be used to develop and verify predictive models. LRE evaluated:

• Interferometric synthetic aperture radar (InSAR) data
• Extensometer data
• Gravity surveys
• Spirit leveling survey data
• Time series water levels from over 7,000 wells

LRE used the water supply model well field drawdown results as input into a one-dimensional subsidence model (SUB-WT package) to evaluate various well field pumping scenarios. We incorporated borehole lithology, geophysical data, and geotechnical laboratory results as model input. We also integrated subsidence empirical relationship data during the development and verification of the subsidence model.

In 2011, LRE provided additional water supply prediction scenario modeling, tested the performance of one-dimensional and three-dimensional subsidence models, and tested the utility of geophysical logging existing water wells. We developed a cost/benefit tool that allows a dynamic ranking of water supply and subsidence field investigation techniques while considering current project goals, schedule, and budget.

One of LRE's significant accomplishments in 2011 was the development of methods for quantifying model prediction uncertainty. This process provided a range of possible calibrated model results and enabled the project team to make statistical "confidence" statements of water availability.

LRE's water supply and predicted subsidence results are being used by decision makers to evaluate overall project feasibility and to scope future investigation and design work. For further information, contact dave.colvin@LREwater.com.