Spiniello Companies, DC Water Complete Piney Branch Sewershed Project

Spiniello Companies recently completed a critical infrastructure project in partnership with DC Water, aimed at rehabilitating aging sewer infrastructure within the Piney Branch Sewershed. This complex and multifaceted initiative took place throughout Northwest Washington, D.C., and played a crucial role in enhancing the structural integrity, hydraulic performance, and long-term sustainability of the area’s combined sewer system.

The Piney Branch Sewershed Rehabilitation project centered on the structural rehabilitation of approximately 13,800 lf of combined sewer pipelines. These pipelines, ranging in size from 36 in. to 78 in. in diameter, spanned a variety of shapes and conditions. Over time, these critical underground assets deteriorated due to age, flow conditions, and urban load demands, necessitating a strategic and technically advanced rehabilitation approach.

Geopolymer Lining System: A Proven Structural Solution

At the core of Spiniello’s rehabilitation strategy was the application of the Geopolymer Lining System (GLS), a next-generation trenchless technology offering superior chemical resistance, high structural strength, and long-term durability. The GLS solution was selected to line over the 13,800 lf of combined sewer pipelines, restoring the original design capacity of these conduits and extending their service life without the need for full pipe replacement.

This method allowed for internal structural rehabilitation with minimal surface disruption — an especially important consideration given the project’s urban setting within high-traffic residential and commercial zones. In addition to the linear footage of pipe, GLS was also used to structurally rehabilitate five large junction chambers — critical nodes within the sewer network where multiple pipes intersect.

Integration of Open-Cut & Trenchless Techniques

To address the diverse technical challenges posed by the condition and configuration of the sewer system, Spiniello implemented a hybrid approach, combining open-cut excavation and trenchless rehabilitation methods. In areas where internal rehabilitation was not feasible due to access constraints, pipe collapse, or hydraulic design limitations, targeted open-cut excavations were performed. However, only one open-cut point repair was ultimately performed. The second originally scoped open-cut repair, located within an active construction site off the roadway, was converted to a trenchless solution due to restricted access to the full lot. Spiniello successfully developed and executed an alternative trenchless method to complete the repair within the limited access constraints, ensuring constructability, cost-efficiency, and minimal community disruption.

Manhole Rehabilitation & Construction

The scope of the project also included extensive work on existing sewer manholes —vital components of the sanitary and stormwater network. A total of 70 manholes were rehabilitated using a variety of methods tailored to each structure’s condition. These included GLS application, step replacement, grade ring replacement and frame and cover replacement.

Three new manholes were constructed as part of the project to improve access and inspection capability for long-term maintenance. All newly constructed manholes were lined with GLS, ensuring consistency in durability and corrosion resistance throughout the system.

Abandonment of Obsolete Infrastructure

As part of the optimization and modernization of the Piney Branch network, approximately 400 lf of existing 36-in. to 51-in. diameter pipelines were decommissioned and properly abandoned in place. This work was performed in the area surrounding Sherman Circle NW, within National Park Service (NPS) property. Additionally, one obsolete junction chamber was also abandoned.

This portion of the project required close coordination with federal and municipal agencies, including the NPS, to ensure that all work within protected areas was compliant with environmental and cultural preservation requirements. Spiniello implemented specialized restoration practices and environmental protection measures to maintain the integrity of the historic parkland.

Bypass Pumping, Dewatering & Site Management

Given the continuous operation of the city’s combined sewer system, Spiniello implemented an internal/external bypass pumping system to ensure uninterrupted flow during rehabilitation activities. Customized dewatering solutions were also employed to manage groundwater inflow during excavation and lining operations.

Erosion and sediment control played a key role in mitigating environmental impacts. Spiniello deployed approved best management practices (BMPs) across all active work zones, including silt fencing, inlet protection, stabilized construction entrances, and daily inspections to ensure compliance with local and federal environmental regulations.

Traffic control was another major aspect of the project’s success. Many of the construction activities occurred within or adjacent to heavily traveled roadways in Northwest D.C. Spiniello developed and executed detailed Maintenance of Traffic (MOT) plans in collaboration with the District Department of Transportation (DDOT) and other local stakeholders to minimize disruptions to commuters and local businesses. Flagging operations, detours, and temporary road closures were all managed with an emphasis on public safety and project efficiency.

Restoration and Project Closeout

Upon completion of all rehabilitation and construction activities, Spiniello Companies restored all disturbed areas to their original or improved conditions. This included full-depth asphalt paving, concrete sidewalk restoration, curb and gutter replacement, greenspace replanting, and restoration of parklands within NPS boundaries. These efforts helped return affected communities to normalcy while enhancing visual aesthetics and preserving public trust. Spiniello successfully completed this project with zero safety incidents, demonstrating our unwavering commitment to safety and operational excellence.

Commitment to Quality & Public Health

The successful execution of the DC Water Piney Branch Sewershed Rehabilitation project underscores Spiniello Companies’ deep commitment to quality infrastructure, public health, and environmental stewardship. By leveraging cutting-edge trenchless technology and maintaining a relentless focus on safety, coordination, and performance, Spiniello helped DC Water extend the service life of its critical underground assets — ensuring continued service to the residents and businesses of Washington, D.C.

This project serves as a model for how modern pipe rehabilitation techniques, when combined with thoughtful planning and skilled execution, can solve complex infrastructure challenges in a way that is efficient, minimally disruptive, and built to last.

Kevin Schnabel is senior project manager, Justin Jacobs is general superintendent and Tim Bako is vice president of corporate strategy at Spiniello Companies.

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