DRAINAGE DESIGN CASE STUDY:

The Durham Wastewater Treatment Plant (WWTP) in Strafford County, New Hampshire underwent a critical drainage system upgrade to improve stormwater management and long-term stability behind reinforced concrete retaining walls. The project addressed rising concerns about hydrostatic pressure buildup and erosion at this vital public utility facility.

To mitigate these risks, engineers implemented a JET Filter weep hole retrofit, supporting better water discharge and wall preservation in a high-moisture wastewater environment.

Wastewater treatment plants like Durham WWTP are constantly exposed to elevated moisture, which can lead to:

• Excessive hydrostatic pressure behind retaining walls

• Soil saturation and erosion

• Cracking and structural movement in concrete barriers

• Increased maintenance for public works teams

To address these challenges, Environmental Partners Group, LLC and the Durham Public Works Department specified a maintainable drainage system that would function long-term with minimal disruption.

In partnership with Apex Construction, the project team installed:

✅16 units of 4” diameter open-end ASTM 316/316L Stainless Steel Housing

✅Geotextile Media: Mirafi® Filter-Weave FW 300

✅Designed for inspection access, debris flushing, and extended service life

These weep hole systems were embedded in the WWTP’s reinforced concrete walls to allow for controlled water discharge while preventing soil migration and erosion under continuously wet conditions.

Retaining walls at wastewater facilities face relentless exposure to:

• High water volumes from rain and runoff

• Backpressure from soil and saturated earth

• Structural degradation without water release systems

Without proper drainage:

• Infrastructure lifespan shortens

• Repair costs escalate

• Water buildup leads to unsafe site conditions

JET Filter’s maintainable weep holes offer a cost-effective, durable, drainage upgrade for retaining structures engineered to withstand high-moisture, debris-laden environments like treatment plants and stormwater channels.