South Englewood Basin Stormwater Improvements Project – Oxford Alignment Rehabilitation

englewood, Colorado

The South Englewood Basin (SEB) Stormwater Improvement project is intended to alleviate the quantity and frequency of flooding events within the basin for the City of Englewood, Colorado. One portion of this improvement effort included addressing the final stretch of outfall piping for the existing SEB stormwater network along the south side of W. Oxford Avenue from S. Navajo Street to the South Platte River; commonly referred to as the “Oxford Alignment”. The Oxford Alignment generally runs east to west along the south side of W. Oxford Avenue and is approximately 3,062 feet in length. This pipeline alignment includes 94-inch by 94-inch reinforced box culvert, 92-inch thin-polymer lined corrugated metal pipe, 78-inch reinforced concrete pipe , solid wall steel pipe, and 78-inch coal-tar epoxy lined CMP. This portion of the system experienced high volume sediment deposits, structural pipe material failures, and multiple sink holes over the last 10 years.

Lithos is supporting HDR, Inc.’s design team for the SEB Stormwater Improvement project, providing condition assessment inspection, rehabilitation design, and construction services for the Oxford Alignment. A comprehensive person-entry inspection was performed and summarized in a complete condition assessment report for the asset. Alternatives to address the condition of the Oxford Alignment while meeting the project specific intents of the overall project were evaluated and a preliminary design along with engineer’s opinion of probable construction cost was assembled by Lithos. Cured-in-place-pipe was selected as the preferred alternative to address the corrugated metal pipe sections of the alignment, and other spot repairs for the rest of the alignment and structures. Construction is expected to begin in 2023 on the project in whole, and the Oxford Alignment will be addressed in early 2024.

Project challenges included balancing the design constraints of the SEB stormwater improvement project, the needs presented by the Oxford Alignment’s condition, and the cost and installation particulars of the proposed improvements. Project success will be defined by the elimination of pipeline failures, reduction of maintenance and cleaning, and delivering the most appropriate, least risk solution for the City of Englewood.

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