Case Study Video: AlexRenew RiverRenew Tunnel System

The RiverRenew program represents a major milestone in Virginia’s combined sewer overflow (CSO) mitigation efforts—and the largest infrastructure project in Alexandria’s history.

As a key member of the Owner’s Advisor team, Schnabel Engineering supported AlexRenew and Brown and Caldwell with comprehensive services throughout the entire program lifecycle, from conceptual planning, geotechnical investigation and tunnel alignment selection to design-build procurement support, and construction management.

The centerpiece of the project is a 2.2-mile-long, 12-foot-wide segmentally lined tunnel that captures and conveys CSO to a new tunnel dewatering and wet weather pumping station at the AlexRenew Water Resource Recovery Facility. The system also includes near-surface diversion structures, drop shafts, a new 6-foot-diameter microtunnel-driven sewer interceptor, and enhanced wet-weather treatment capacity—designed to comply with Virginia’s 2026 CSO compliance deadline.

This case study video explores the program’s engineering complexity, sustainability goals (including LEED and Envision certifications), and community-driven design in a dense urban environment.

Watch the video to learn how multidisciplinary collaboration, innovation in underground construction, and strategic stakeholder engagement are delivering long-term environmental benefits.