Barr Lake Spillway

Barr Lake Spillway

The State of Colorado determined that the spillway at Barr Lake was inadequate to safely pass the inflow design storm. ERC was retained to evaluate existing and future conditions and design a spillway upgrade. ERC evaluated extreme precipitation conditions and defined the Probable Maximum Precipitation of 30 inches in a 48-hour period. When routed the storm produced a peak inflow rate of approximately 40,000 cfs with a total runoff volume of 13,000 acre-feet. Hydraulic modeling showed that a 185 spillway was required to safely pass the inflows while maintaining the required freeboard without raising the dam. The design included replacing the existing earthen spillway with a composite concrete, riprap and soil cement spillway. Additionally, over three miles of perimeter dikes were designed and constructed to control water levels during the design event. ERC completed design, permitting and construction management for the project.

Project Categories:
irrigation

Burlington Canal Headworks

Burlington Canal Headworks

ERC designed and oversaw construction to modernize the main Burlington Canal headworks off of the South Platte River. The diversion structure included four main crest gates (two 6 foot gates and two 12 foot gates) a 4’ x 13’ crest gate for bypass flow operations and a 4’x4’ sandout gate all with flow measuring capabilities. ERC’s work included hydraulic modeling, gate design, 404 and floodplain permitting and construction observation. The completed facility has the ability to pass and measure flows up to approximately 1,000 cfs. Gates were designed to fit within the original Burlington diversion structure while improving operational flexibility and safety.

Project Categories:
irrigation

Church Ditch Headgate 53 Retaining Wall

The Church Ditch hired ERC to repair a concrete-block retaining wall holding back high banks along the ditch in Arvada. The wall showed signs of heaving and overturning in several spots due to a poor design and the expansive soils in the area. ERC designed a concrete footer for the existing blocks and a system of steel angles to tie the blocks together. Approximately 800 linear feet of wall was repaired. The sections were between 6 and 10 feet tall. Design work included hydraulics, stability analysis, and permitting. ERC also managed the project by providing construction oversight.

Project Categories:
irrigation

Church Ditch Headworks

CDWA headworks

In 2016-2017, ERC managed the project to modernize the headworks structure of the Church Ditch on Clear Creek in Golden, Colorado.  During the design phase, ERC conducted hydraulic modeling to size new gates.  These included two 4-ft by 4-ft Fresno slide gates, a 4-ft Rubicon overshot gate for controlling upstream head, and a 4-ft slide gate for flushing debris.  We also worked with the City of Golden and Jefferson County Open Space to permit the project.   In the construction phase, ERC provided bid support to select a contractor then provided oversight and observation to ensure a smooth process.  The structure includes security fencing, solar power and the ability to operate the gate and measure flows remotely.

Project Categories:
irrigation

Church Ditch Leyden Flush Structure

The Leyden Flush Structure is a turn-out point for Church Ditch to bypass excess flows and flush sediment and other debris from the upper system. In 2017, the Church Ditch hired ERC to design a new structure to replace the leaky gates, old concrete rickety bridges and a manual stop-log system. ERC designed a new structure to include two concrete headwalls, a 12-ft by 4-ft canal slide gate, a 4-ft by 4-ft Rubicon SlipGate for flushing, two steel access bridges, and security fencing. The gates are solar powered and remotely operable. Design work included hydraulic modeling and gate sizing.   ERC also managed the project by providing construction oversight.

Project Categories:
irrigation

Community Ditch Improvements

The Community Ditch through Eldorado Canyon was historically one of FRICO’s most difficult sections to maintain of its 400 mile canal system. Bank sloughing, icing, seepage, liner damage and limited access all contributed to operational challenges in this section. FRICO hired ERC to develop a solution that would allow water to be conveyed through this ½ mile section in a more efficient manner. ERC’s solution replaced the open trapezoidal channel with a box culvert. The culvert was designed to fit within the narrow, meandering confines of the old ditch alignment, which allowed for only inches of tolerance in the box design. Maintenance access, which had not existed through this section, was provided on the top of the culvert. Design work included hydraulic modeling, modifications to intake gates and measuring devices, evaluation of rockfall hazards and Boulder County permitting.

Project Categories:
irrigation

Dam Breach Modeling

Hydrology

ERC has completed several dam breach analyses for municipal reservoirs and mining facilities in states such as Colorado, Arizona, Montana, and South Carolina, among others. The analyses have included sizing flow hydrographs resulting from a dam breach, mapping flood inundation extents (using both one-dimensional and two-dimensional modeling methodology), and determining the downstream hazard classification of each dam in respect to local regulations. ERC has also aided in the creation of Emergency Action Plans (EAPs) for the dams where the downstream hazard potential of the dam is found to be great enough to require one.

Project Categories:
irrigation

Standley Lake Monitoring and Dam Break

Standley Lake Monitoring and Dam Break

ERC is responsible for the on-going monitoring and reporting of Standley Lake Dam in Westminster, CO. This large, high-hazard dam provides water to nearly 300,000 residential and is located in a highly urbanized area. ERC completes monthly inspections, monitors reservoir and phreatic levels, evaluates crack gages and inclinometers and provides reports to dam owners and the State Engineers Office. For emergency planning purposes ERC has modeled dam breach scenarios and prepared inundation mapping for use by local emergency managers. We have designed repairs to ancillary facilities including outlet works, the dam’s spillway and the headgate structure that diverts up to approximately 1,000 cfs into the Lake.

Project Categories:
irrigation