Urban Drainage / Floodplain Projects

Huston Lake Rain Garden, Denver 

The design of the rain garden at Huston Lake serves a 13.6-acre drainage area including 6.8 acres of residential streets, roofs, and drives. The primary design philosophy was to create a multi-functional facility that is effective and easy to maintain. The forebay was integrated into the street section and doubles as on- street parking, which allows for cleaning under the existing routine street sweeping program. A specially designed curb section with tapered orifices from the inlet to the outlet convey water from the forebay to the turf grass infiltration zone. The tapered openings encourage debris and sediment removal in the forebay, and can be easily cleaned from the wider downstream opening. The planting mix used was based on Muller’s office seed mixture research results and includes amendments of Biosol, a slow-release fertilizer, and granular iron (for binding of phosphorous). The turf grass consists of sand grown sod, which has a higher infiltration capacity than regular sod and can be maintained in the same fashion as the remainder of the park.

Left Hand Creek, Longmont

A complex hydraulic system in Longmont, Colorado with eleven flow splits and 211 structures within the regulatory 100-year floodplain was analyzed. Improvements designed to take 172 structures out of the 100-year floodplain consist of two pedestrian bridges, an enlarged box culvert crossing at Main Street, an enlarged culvert at South Pratt Parkway, roadway modifications at Pike Road, and a continuous trail system.

Sulphur Gulch at Riva Ridge Street and Canterbury Parkway – Parker

For this project, Muller provided design and construction observation services for channel stabilization of Sulphur Gulch at two locations. Upstream of Riva Ridge Street work included retrofitting an existing sculpted concrete drop structure, and designing a new integral sculpted concrete drop structure and trail crossing to replace an existing undersized trail crossing, channel grading to create a bankfull cross section and transition the proposed improvements to the existing channel and bioengineered bank protection. These improvements also provided increased flow capacity to ensure that the 100-year floodplain would not encroach onto adjacent residential lots.

Downstream of Canterberry Parkway, Muller designed a sculpted concrete drop structure at the outfall of the existing Canterberry Parkway box culvert and trail underpass to stabilize existing downcutting of the downstream Sulphur Gulch channel that was threatening to undermine the Canterberry Crossing. Then project also included channel grading to tie-in to the existing downstream channel and bank protection.

Huston Lake Rain Garden
Left Hand Creek
Sulphur Gulch