Comprehensive Survey to Guide Rehabilitation and Address Changing Site Conditions

Starting later this week, DC Water will conduct an aerial drone assessment along the 54-mile Potomac Interceptor (PI) to evaluate current site conditions and better understand the changing landscape and development along the Potomac Interceptor alignment, including areas where there may be rocks or boulders that need further on the ground inspections.

This effort is part of a comprehensive plan to assess conditions following the January 19 collapse along Clara Barton Parkway and the C & O Canal National Historical Park by I-495 in Cabin John, Maryland. During the collapse, large rocks and boulders excavated and used as backfill during original construction blocked the pipe, creating an unprecedented overflow not normally seen when a pipe fails.

Drone flights will occur over the next month, using LIDAR (Light Detection and Ranging) scanning to create high-resolution, three-dimensional maps of buildings, vegetation, and the ground surface.

The collected data will support accurate mapping and strategic planning for DC Water’s ongoing 10-year, $625 million rehabilitation of the interceptor.

This marks the first time an analysis has been conducted on the Potomac Interceptor utilizing the latest aerial mapping technology. Previously, reviews were limited to available satellite imagery, which provided only a general overview of site conditions. Since the pipeline's original construction in the 1960s, both the ground surface and surrounding development have changed dramatically along its alignment. Having a detailed aerial inspection is essential for accurately documenting these changes and understanding their potential impact on future rehabilitation work.

Drones will fly at approximately 300-350 feet, coordinated with the Federal Aviation Administration, particularly in restricted airspace. Flights will follow a set route, with several landings and takeoffs as needed. Survey equipment will be carried by larger drones, which have flashing navigation lights.

Survey teams will place yellow and black temporary ground markers throughout the area. Please do not move these markers, as they are critical for confirming aerial data accuracy.

IMPORTANT INFORMATION

• Dates: March 26 – April 3, 2026
• Hours: 8:00 a.m. – 3:00 p.m., Monday–Friday, weather dependent
• Impacts:
  • No impact to traffic in the area.
  • No impact to internet or wireless services. The aerial survey will not interfere with internet, Wi‑Fi, or cell phone connections in your area.
• The equipment used is safe. The drones and survey equipment do not emit harmful signals and do not pose any risk to public health or safety.

DC Water is on a condensed timeline to get the aerial inspections complete, before trees and vegetation grow in that would block visibility. In addition to the aerial drone operations, inspections are also ongoing to assess conditions inside the pipe. This will allow for a comprehensive understanding of both external and internal conditions to support ongoing maintenance and rehabilitation efforts on the Potomac Interceptor.