Boulder Creek Master Plan

Boulder Creek Master Plan

Boulder Creek, like many of Colorado’s front range streams, was significantly altered by the 2013 floods. ERC was part of a team of consultants tasked with evaluating the environmental and geomorphologic conditions of the stream and developing a master plan for future resilient improvements. ERC evaluated historic aerial photographs of Boulder Creek to understand evolution of the stream’s alignment during recent and pre-development periods. From this assessment, a range of natural sinuosity and meander wavelengths were defined and alignments for future restoration were identified. Typical cross-sectional geometries that replicate natural stream conditions were determined for low flow, bankfull flow and flood flow events. Critical habitat features along the riverine corridor were defined and recommended riparian buffer zones to protect the corridor from further development were determined.

Project Categories:
stream-assessments

Denver Water Moffat Project

Moffat EIS

ERC was the stream morphology and sediment transport resource specialist tasked with evaluating impacts of Denver Water’s Moffat project on front-range and west slope stream systems. Channel evaluations encompassed over 200 miles of streams including the Fraser, Williams Fork, Colorado and Blue River on the west slope and South Boulder Creek and the North Fork of the South Platte River in the front range. Field work included site assessments, surveying and sediment sampling. Existing stream conditions and recent trends in channel evolution were evaluated from this field program, evaluation of historic conditions (aerial and ground photos, assessment of USGS stream gage shifts and repeated historic cross-sectional surveys for signs of aggradation or degradation) and numeric modeling. Modeling defined sediment supply, sediment transport capacity, effective discharge, the frequency of Phase 2 sediment transport and the magnitude of specified recurrence interval flood flows. Quantitative and qualitative stream impacts anticipated as the result of the planned Moffat project were determined by defining flow changes associated with the project and overlaying these hydrologic alterations on knowledge of the behavior and resiliency of the existing stream systems. ERC’s work included design of front-range and western slope stream mitigation aimed at providing functional stream uplift to offset project impacts following the stream functional pyramid approach.

Project Categories:
stream-assessments

Haile Gold Mine Stream Assessment and Monitoring

Haile Gold Mine Stream Assessment and Monitoring

The Haile Gold Mine is going to alter flows in area streams within and adjacent to the mine development. ERC was retained to evaluate and document flows and stream conditions within the mine, adjacent to development and in areas outside of the zone of influence of the mine to facilitate the long-term assessment of potential mine impacts. Baseline studies included stream surveys, sediment sampling, bank stability evaluations and flow quantification. As part of this initial assessment ERC established permanent monitoring sites and designed a system of flumes, weirs and USGS type stream gages for flow measurements. Nested piezometers were designed and installed to inform the understanding of variability in surface flows and groundwater levels and their joint contributions to the riparian wetland system that exists on site.

Project Categories:
stream-assessments

Trout Creek Stream Assessment

Trout Creek Stream Assessment

Peabody Coal’s planned Trout Creek reservoir would alter the flow regime, sediment conveyance and stream conditions in Trout Creek. ERC was hired as part of the FERC process to evaluate baseline stream conditions and assess potential impacts of the planned on-line dam. Field work included stream classification, cross sectional and longitudinal stream surveys, pebble counts, suspended and bedload sediment sampling and bank stability characterization. Using this exiting conditions data, ERC projected sediment inflows to the reservoir and changes in sediment conveyance and channel morphology that could be expected to occur as a result of the dam.

Project Categories:
stream-assessments