Oasis Pond Iron-Enhanced Sand Filter

Background

Oasis Pond is located in the City of Roseville’s Oasis Park. The pond was created as a result of the impoundment of Ramsey County Ditch 4 (CD 4). Stormwater runoff to the pond is generated from urbanized land that is mostly untreated. The outflow of the pond is subject to high concentrations of fine sediment and dissolved phosphorus, exposing Oasis Pond and flows downstream to impaired water quality.

The Rice Creek Watershed District (RCWD) hired HEI to complete a feasibility study to install an iron-enhanced sand filter (IESF) system as a best management practice (BMP) for Oasis Pond. Because of insufficient grade on the site, the system would require the use of a lift station. HEI supported the District to secure funding through a Clean Water Fund (CWF) grant from the Minnesota Board of Water and Soil Resources (BWSR).

The Project

HEI began the project by developing preliminary design construction plans based on the feasibility study. These plans included a wetland delineation report, technical specifications, and a preliminary opinion of probable construction cost (POPCC). The system included an elaborate control system to facilitate pumping operations into two IESF infiltration beds.

Once the initial plans were developed, HEI solicited feedback from the RCWD and the City of Roseville in a project review meeting. The feedback received was integrated into the final design plans and POPCC.

Once final designs were completed, HEI provided solicitation support services. Upon selection of a contractor, HEI performed construction observation activities to ensure the IESF was constructed per the final design.

This project was completed and operational in the fall of 2018.