Sanitary Sewer

Sewer System Overview
Sewer System Overview

DC Water is responsible for wastewater collection and transmission in the District of Columbia, including operation and maintenance of the sanitary sewer system. DC Water's sanitary sewer system includes approximately 600 miles of large interceptor sewers and smaller gravity collection sewers. DC Water is also responsible for sewer lateral connections from the sewer mains to the property lines of residential, government, and commercial properties. In addition, DC Water is responsible for the 50 mile long Potomac Interceptor System, which provides conveyance of wastewater from areas in Virginia and Maryland to Blue Plains. The existing sanitary sewer system in the District of Columbia dates back to 1810, and includes a variety of materials such as brick and concrete, vitrified clay, reinforced concrete, ductile iron, plastic, steel, brick, cast iron, cast in place concrete, and even fiberglass.

During 2009, DC Water will review the draft Sewer Facility Plan and recommendations based on the Sewer Assessment Program conducted during the last several years. DC Water will continue the evaluation of the sewer system as an ongoing program to determine its condition, verify adequate capacity, and prioritize and develop new capital projects, as appropriate. The projects selected to be included in the CIP were based on inspections performed on approximately 80 miles of the District's most critical sewer segments. The criticalities of these sewers were developed based on several factors including size, age, historical problems, and locations such as under buildings. A new program management contract (EPMC-IIIB) will continue the inspections and assessment program as well as providing project management services for active projects.

Collection Sewer Projects

Sewer Pumps Ready for Installation
Sewer Pumps Ready for Installation

This program includes studies and projects to effectively eliminate stormwater, groundwater, and other infiltration and inflow to the sewer system, to separate stormwater flows, and to reduce other extraneous flows to Blue Plains. This category also includes projects to rehabilitate collection system sewers as well as projects that serve existing properties and new development. Noteworthy projects are:

East Side Interceptor Rehabilitation
The portion of the sewer that traverses the National Arboretum has significant structural distress. Design is underway for the rehabilitation of the sewer with construction scheduled to start in 2009.
Sewer Rehabilitation on 10th & 12th Streets, NW
This project consists of rehabilitation of deteriorated 36" and 30" diameter sewers on 10th Street, NW and on 12th Street, NW in the vicinity of Pennsylvania Avenue.

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Ongoing Sanitary Sewer Projects

This area includes capital projects managed by the Department of Sewer Services including the replacement of sewer laterals and related capital improvements.

Pope Branch Sewer Rehabilitation
This involves the complete rehabilitation of the existing sanitary sewer that runs along Pope Branch as part of an intergovernmental project to restore the park. Project includes rehabilitation of approximately 4400 feet of sewer.

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Pumping Facilities

This program includes projects required for the rehabilitation or replacement of existing wastewater pumping stations as well as projects for the engineering and construction of new wastewater pumping facilities, as needed to enhance reliability and integrity of DC Water's sanitary sewer system. In addition, a security upgrade is scheduled to begin in mid 2009, which will place interior and exterior cameras throughout DC Water's Sewer Services Facilities, install traffic control devices, and install perimeter fencing. Additionally, this program includes the Authority's planned relocation of certain facilities located at the Main and O Street Pumping stations, as described in more detail below.

The current program includes projects to rehabilitate three existing wastewater pumping stations:

  • Rock Creek Pump Station — The design is complete and construction is underway.
  • Upper Anacostia Pump Station — The pumping station design is complete and construction is underway.
  • Earl Place Pump Station — The facility was placed in service in November 2006.

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Sanitary Sewer Service Area — Management

During 2009, DC Water will continue with an ongoing evaluation of the sanitary and combined sewer systems, as well as design management for sewer pumping station rehabilitations and sewer infrastructure projects:

Sanitary Sewer Program Management & Planning (EPMC-IIIA/IIIB)
This project provides design, review and management of the sewer system to determine if it is in an adequate structural condition, and has sufficient capacity to meet current service demands and planned growth. The planning effort is also required to comply with the current National Pollutant Discharge Elimination System (NPDES) permit, the Nine Minimum Controls consent decree, and prevention of non-permitted sewer overflows.
Design Management for Sanitary Sewer Pumping Stations
This ongoing project began in 2001, and provides for the management of the design and construction of three small sanitary sewage pumping stations requiring major rehabilitation or replacement. Rock Creek Pump Station design is complete and construction is underway. Upper Anacostia Pump Station design is complete and construction procurement is underway. Earl Place Pump Station was placed in service in November 2006.
Sewer Inspection Program
This program, began in early 2008, provides an on-going effort to further inspect the Authority's existing sewer system at a rate of approximately 90 miles of sewer lines per year. The resultant information will assist in the scheduling and prioritization of sewer main line and lateral repair work.
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Interceptor/Trunk Sewer/Force Sewers

Crews at work constructing part of the East Side pumping station
Crews at work on the East Side Pumping Station

This program includes large diameter sewers that may be required to serve new development, replace undersized sewers, or replace or rehabilitate large diameter sewers that have reached their useful life or are in need of major repair. In addition, this category includes sewer projects that were identified as part of the comprehensive assessment of the sewer system.

Potomac Interceptor Rehabilitation
The Potomac Interceptor Sewer System is a 50-mile long sewer that provides conveyance of wastewater from areas in Virginia, Maryland and the District to Blue Plains. DC Water has been working with its wholesale customers on a variety of capital projects to address odor control issues related to the Potomac Interceptor and to ensure the long-term structural integrity of this major sewer. The project has faced challenges, such as, larger equipment needed to control odors, high architectural costs related in part to historical preservation requirements of the National Park Service, and difficult construction locations, including:
  • Potomac Interceptor Rehabilitation in Fairfax and Loudoun Counties
  • Additional Inspections and Access Road Improvements — Three projects are included to further assess over 20 miles of the pipeline, improve deteriorated access roads for operations and maintenance needs, and to evaluate soil erosion along the pipeline at stream crossings and along the banks of the C&O Canal.
  • Potomac Interceptor Repair at Waxpool Road — This project involves the relining of 930 feet of the 48-inch Potomac Interceptor in Loundoun County near Waxpool Road. The final design was submitted in -2008 after the original contract was modify to remove a portion of the Upper Potomac Interceptor repair in Washington DC due to unresolved access issues with the National Park Service. The repairs to the PI at Waxpool Road are scheduled for early 2009.
Odor Control Projects
  • Interim Odor Controls — As an interim step, DC Water installed odor-absorbing chemicals and passive carbon filters in manholes at selected locations where problems have been experienced. This interim project cost approximately $0.4 million and was completed in October 2000. These interim controls have been continually maintained, pending the implementation of the permanent odor controls, currently scheduled to begin in 2010.
  • Permanent Odor Controls — DC Water plans to install a permanent odor control system that includes a forced air/activated carbon filter system. The conceptual design was completed in 2003. During the past five years, DC Water has been seeking the requisite National Park Service permit, performing associated environmental assessments, and coordinating with the community. Permits and property access issues are continuing and recent acceptance of architectural features by the National Park Service indicate that DC Water is nearing completion of all coordination issues. DC Water expects construction on the facilities to begin in 2010.
Upper Potomac Interceptor Rehabilitation
This project involves the repair of a major portion of the trunk sewer. This project was separated out as a stand alone contract due to access restriction and ongoing negotiation with National Park Service. The design is scheduled to be completed in 2009, and construction is anticipated to start in early 2010.
Future Sewer System Upgrades
  • Tide Gate Replacements — Design was completed in 2008. Construction scheduled for 2009. This project is for the replacement of the structures at various outfalls to prevent the river from flowing into the combined sewer system during high tides. It is estimated that approximately 40,000 gallons per day of river water that is currently being treated at Blue Plains AWTP can be prevented from entering the combined sewer system upon completion of the project.
  • Georgetown Sewer Rehabilitation — Design was completed construction began in late 2008. Combined sewer inspections performed throughout the Georgetown neighborhood of the District found severe structural defects in the existing sewer system. This project is for the design and construction for rehabilitation of approximately 2,600 feet of the existing sanitary system. This project will utilize trenchless technologies to limit the impact to the existing neighborhood.
  • Watts Branch Sewers Rehabilitation — The DC Department of Environment (DDOE), DC Water, and United States Fish & Wildlife Service (USFWL) are working together to design plans for the Stream Restoration of Watts Branch. The sewer system improvements are being performed by DC Water staff. Preliminary design drawings and permits completed in 2008. The project was to be broken into three phases 1, 2, and 3 and involves the improvements to the sewers along Watts Branch. Phase 1 work was necessary to begin prior to the USACE / DDOE Stream restoration projects. It involved three sites for excavation and some lining of a few sewers that currently cross Watts Branch. Phase 2 involves the relocation of the Watts Branch interceptor for approximately 2 blocks to eliminate 3 (or 4) sewer crossings of Watts Branch as well as lining of the interceptor from west of Grant Street / 46th Street to where the sewer exits the park. Phase 3 is miscellaneous work such as manhole lining or additional manhole placement for ease of maintenance.
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Projects scheduled to begin in 2009

B St/New Jersey Ave Trunk Sewer Rehab
This project will rehabilitate the numerous defects noted in this early 1900's brick sewer, as detailed in the condition assessment study completed in the 2004 inspection program.
Upper Anacostia Main Interceptor (UAMI) Relief Sewer
This project involves the replacement of approximately 2000 LF of 18-inch separate sanitary sewer installed 70 years ago with a 30-inch relief sewer. This will relieve the UAMI from surcharging during high flow periods minimizing flooding and back-ups, and was moved forward from 2013. This will also provide capacity for the high level of development that is revitalizing Anacostia Gardens, Lily Pond and Kenilworth Terrace neighborhoods.
Oxon Run Sewer Leakage Correction
This project assesses the condition and develops needed repairs for a segment of sewer that crosses Oxon Run. Project scope includes additional sewer rehabilitation (7,700 linear feet of 12 inch to 36 inch diameter sanitary sewer) and pilot study to eliminate infiltration (450,000 gpd estimate).
Low Area Trunk Sewer Rehabilitation
Project created in response to unanticipated structural collapse on Low Area Trunk Sewer which was recently fixed in one location. Inspection and cleaning to be performed prior to expected rehabilitation. Necessary rehabilitation to be determined post inspection and cleaning.

New Projects added to this service area in 2009

Sewer Rehab Near Creek Beds
The Sewer Assessment Program identified several areas within the city's stream valleys where sewer systems have become exposed due to creek bed erosion. The overall program budget is being reviewed as part of the draft Sewer Facility Plan, however, start up funds were programmed to begin planning, design and coordination with park authorities so progress can be made during the review of the overall program budget costs.
Sanitary Sewers Under Buildings
This project rehabilitates sanitary sewers located under buildings citywide. Other activities included in this project are cleaning, pre and post CCTV, sealing joints and repair of offset pipe.
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