Hillaryville Regional Wastewater Treatment Plant

Ascension Parish, Louisiana



Through a federal program to fund Environmental Infrastructure programs within local municipalities, MSMM representing the USACE New Orleans District, worked with the Ascension Parish Government, LA (non-Federal sponsor) to design a regional wastewater treatment plant (WWTP) adjacent to the recent MSMM designed sewer effluent pump station (separate task order). This area of Ascension Parish utilizes a fragmented system of treatment options with subpar results that vary by subdivision based on each developer at the time.  It includes septic tanks, package treatment plants, and an oxidation pond all of which discharge into local ditches and streams.  High growth in this area of Ascension Parish including a large new subdivision being added and expansion of existing subdivisions will continue to contribute to a poor environmental situation.  The WWTP was one step of a regionalization plan MSMM was involved in developing to bring all wastewater in the area to a single advanced treatment facility that would eventually discharge the treated effluent into the Mississippi River in lieu of local ditches.

For this project our team was responsible for providing 100% bid ready plans and specifications (in USACE format) for a new 1.8 million gallon per day (mgd) average daily flow WWTP to increase treatment capacity and facilitate the regionalization of the Parish.  The treatment plant design includes a new treatment plant on an eight (8) acre parcel of land owned by Ascension Parish. The design consisted of a dual set of treatment processes for redundancy and included an influent pump station, headworks with screens and grit removal, extended aeration basin, circular clarifier, chlorine contact chamber, aerobic digesters, belt filter press with new building, maintenance/administration building, and emergency generator as well as site drainage and internal asphalt roadways. The facility is designed so that a future aeration basin and clarifier can be constructed to easily upgrade the treatment plant to 2.7 mgd as additional capacity is needed.

In addition to the bid ready design documents, our team is also responsible for project permitting through USACE, LADEQ, LADHH, LADOTD and CPRA of Louisiana. Additionally, our team was responsible for detailed MCACES cost estimating, presentations at public meetings, survey and detailed geotechnical investigations. Under construction phase services our responsibilities shall include shop drawing review and approval, RFI’s, site visits and project meetings. The project construction is currently not scheduled and MSMM has completed 100% design for this project pending final review.


Ascension Parish, Louisiana


USACE New Orleans District


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