CITY OF NORTHGLENN WASTEWATER TREATMENT PLANT AND BULL RESERVOIR DAM MODIFICATIONS

Northglenn, Colorado

The project included design and construction of a new wastewater treatment plant at the site of existing Bull Reservoir. Bull Reservoir is a Class I dam under the jurisdiction of the State Engineer's Office (SEO). The project included new pipelines which penetrated the existing embankment dam. The pipelines were considered a modification to the embankment dam and as such required formal submittals, review, and approvals by the SEO.

Lyman Henn planned and implemented a geotechnical siting study for the plant. Existing geotechnical data was reviewed and was supplemented by additional investigations. A design-level investigation was performed and foundation recommendations were provided along with detailed constructability considerations. Subsurface conditions and the resulting foundations recommendations were complicated due to an erratic bedrock surface and abrupt differences in the nature of the overburden soils.

Lyman Henn also performed a geotechnical evaluation of the proposed dam modifications and provided recommendations concerning the details of pipeline design and construction to stratify SEO requirements. Lyman Henn's design services were followed through with drilled shaft observations and backfill compaction testing during construction.