Sanitary Sewer Master Plan

Page updated on Oct 26, 2021 at 9:22 AM

Project Documents and Presentations


The City has finalized the update to the 2013 Sanitary Sewer Master Plan that provides a summary of the City’s sanitary sewer assets, existing infrastructure needs and future needs to accommodate forecasted growth, and strategies for addressing sanitary sewer backups that can occur due to extreme wet weather and flooding. Key findings and recommendations of the plan are discussed below.

Sanitary Sewer Capacity Needs

Growth forecasts are used to analyze the capacity of the City’s sanitary sewer collection system, Alexandria Renew Enterprises (AlexRenew) interceptor sewers and wastewater treatment plant capacity. The results of the analysis completed indicates the following:

  • A small portion of the City’s sanitary collection system require capacity improvements. The City will begin programming capacity improvements for sewers that do not have sufficient capacity as part of its FY2023 Capital Improvement Program (CIP). Sewer capacity upgrades due to growth will be a requirement of development projects.
  • Future capacity improvements will be required in the Holmes Run Trunk Sewer and in the Potomac Yard Trunk Sewer and will be programmed in a future CIP.
  • An additional 4 mgd of treatment plant capacity at AlexRenew will be needed starting between 2040-2045. Alternatives for obtaining additional treatment plant capacity have been identified and will be evaluated and results shared as part of the next update to the Sanitary Sewer Master Plan.

Strategies for Addressing Sewer Backups

Several projects and initiatives to maintain the sewer system infrastructure and reduce sanitary sewer backups that occur during extreme wet weather have been or are in the process of being initiated and funded, including the following:

  • Continued funding for the City’s Backflow Preventer Assistance Program. This program reimburses residents 50 percent of the cost of installing a backflow preventer, up to a maximum reimbursement of $2,000.
  • Implementation of the Sanitary Sewer Asset Renewal Program to maintain the integrity of the sanitary sewer system and reduce the amount of infiltration and inflow (I/I) into the sewer system.
  • Development of the framework of a private property I/I reduction program.
  • Implementation of a Fats, Oils and Grease (FOG) Program.
  • Sewer upsizing projects in the separate sanitary system and sewer separation projects in the combined sewer systems where backups have occurred.
  • Addition of two engineering positions to the Sanitary Infrastructure Division.

Sanitary Sewer Fees

The Sanitary Sewer Master Plan includes a review of existing sanitary sewer fees and provides recommendations for fee changes. Changes to the fees can only be done through a change to the City’s ordinance. Following adoption of the Sanitary Sewer Master Plan (planned for November 2021), staff will be bringing the required ordinance changes to City Council the following month. The recommendations to the sanitary sewer fees include the following:

  • Changing the sanitary sewer user fee billing basis from monthly water usage to winter quarter consumption to more accurately reflect water that reaches the sanitary sewer system. On average, it is anticipated this will reduce the City’s charges on the monthly sewer up to two dollars per month on an average residential sewer bill.
  • Changing to the sanitary sewer connection (tap) fees that are charged as part of development, including:
    • Increasing the teardown credit
    • Establishment of senior living as its own use
    • Update the non-residential fees

This report has been prepared by the Department of Transportation and Environmental Services with input from the Department Planning and Zoning and Alexandria Renew Enterprises. For more information about the plan or to provide comments/feedback, please contact Erin Bevis-Carver, Sanitary Infrastructure Division at 703.746.4154 or at