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Compensatory Stormwater Storage for New Restaurant in Haverhill

Project Specifications:

Location: Haverhill, MA

Application: Compensatory Storage | Detention

Number of Basins: 2

Product Used: 3’-0’’, 3’-10’’, and 4’-7’’ SingleTrap (Basin 1);  1’-6” SingleTrap (Basin 2)

Number of Pieces: 14 (Basin 1); 6 (Basin 2)

Total Water Stored: 5,214 cf

Foundation: Concrete Slab


Owner: River’s Edge Plaza

Consulting Engineer: Allen & Major Associates, Inc.

General Contractor: Amaral Revite, Inc.

Installing Contractor: Digger’s Landscaping, Inc.

A new fast-food restaurant was built in Haverhill, MA, adjacent to the Merrimack River, near Riverside Park. Since the property is located in a floodplain area, the new construction had to be set above the 100-year base flood elevation to ensure no future flood damages. In this case, the elevation had to be approximately five feet above the existing parking lot and surrounding buildings. A StormTrap system was utilized to provide compensatory storage on the site while still providing access to the building.


In order to construct vehicle access to the proposed elevated building, a large amount of fill would be needed to raise the site which was not allowed in the floodplain area. Additionally, as the existing parking lot to remain was far below the floodplain elevation, any access provided to the elevated building would require compensatory storage equal to or greater than the volume of fill placed in the floodplain, explained Michael Malynowski, P.E., Senior Project Manager at Allen & Major Associates, Inc (A&M).


The project engineers at A&M worked closely with StormTrap’s design and engineering team to comply with the site requirements and design a system that would fit under the restaurant’s drive-thru access. After considering several options, the team decided to make the system open at the lower elevations for compensatory flood storage. The system allows for the free passage of potential floodwater to enter and exit the site unencumbered. One basin was installed under the back of the building with different heights SingleTrap pieces (3’-0’’, 3’-10’’, and 4’-7’’) due to the drive-thru slope. A second basin was placed under the right side of the building and six, 1’-6’’ SingleTrap pieces were used.


The StormTrap system was selected for its modularity, flexibility, and ability to support H20 loading. The project was successfully completed ahead of schedule. “The experience with StormTrap was exceptional, from the beginning stages, through engineering design iterations to completion,” stated Malynowski.