The expansion and upgrade of the Peirce Island wastewater treatment plant in Portsmouth, NH was completed by the end of August 2020. Penetron crystalline products were specified as a waterproofing solution for the massive concrete structures.
The $70-million upgrade project was the largest single construction project ever undertaken by the City of Portsmouth, New Hampshire. Designed by AECOM, an engineering consultancy, the upgraded Peirce Island facility now provides secondary treatment and nitrogen removal that meets strict federal environmental standards. The upgrades added to the 50-year-old plant by Methuen Construction, the project contractor, include a new filter building with a biologically aerated/anoxic (BAF) filter (using the Kruger BioSTYR™ technology), a new headworks building with a garage, electrical room, IT room, and control room, and a new solids building with the existing solids building re-purposed as an operations/lab building.
Originally constructed in 1965 to treat an average daily flow of 1.5 million gallons of wastewater per day (later expanded to 4.8 million gallons of wastewater), the upgraded Peirce Island WWTP now handles a daily flow of up to 6.1 million gallons of wastewater. The treated wastewater effluent is discharged to the Piscataqua River through a 24 inch diameter single port outfall.
Better Protection for Local Water Quality
“Some components from the previous plant remain in the new layout but the upgrade work was significant,” adds Christopher Chen, Director of The Penetron Group. “The improved capabilities of the new plant to remove nitrogen from wastewater and treat previously untreated stormwater run-off is essential for protecting the quality of the Piscataqua River, which receives the treated effluent from the plant.”
AECOM specified Penetron products for the new concrete structures, especially the new BAF building, which is approximately 25 feet above the existing grade with another 15 feet of the structure below grade. The walls of the building are massive 2 foot thick concrete structures measuring about 40 feet tall, with the longest wall over 200 feet in length. J.G. MacLellan Concrete Co., the ready-mix supplier, added PENETRON ADMIX to about 17,000 yds3 of concrete mix, which was mostly used for the BAF building walls and foundation.
Keeping Water and Chemicals Out of Concrete
Crews also waterproofed tank walls of the WWTP with PENETRON, a topically applied crystalline material. Like PENETRON ADMIX used for the BAF building, PENETRON penetrates deeply into the concrete structure, filling micro-cracks, pores and capillaries with an insoluble crystalline formation. This prevents water and water-borne chemicals from entering the concrete structures, even under high hydrostatic pressure. In addition, any cracks that do develop during the lifetime of the concrete are waterproofed by the self-healing abilities of PENETRON, resulting in waterproof and durable concrete for the lifespan of the structure.
“The new Peirce Island facility offers increased treatment capacity, cleaner effluent and – thanks to Penetron crystalline technology – a markedly more durable treatment plant with decreased maintenance requirements,” notes Christopher Chen.