Project Overview

GPRS Project Manager Darrell Fernandez was deployed to San Pablo, California, where a contractor was installing deep well anodes along a gas distribution line in a residential neighborhood. Fernandez validated 811 registered utility markings and identified an unmarked stormwater system that was obstructing the planned path of an 80-foot trench, ensuring the secure installation of deep well anodes along an existing gas distribution line.

Deep Well Anodes: Purpose and Function

Deep well anodes are vertically installed electrodes designed to mitigate corrosion in buried infrastructure such as pipelines and storage tanks. These anodes are positioned within a conductive backfill inside a drilled well, ensuring optimal electrical conductivity to protect critical underground assets. By connecting to a power source, anodes generate a protective current that prevents corrosion of the protected structures, serving as sacrificial components that deteriorate in place of essential buried infrastructure.

Challenges in the Excavation Process

The contractor adhered to regulations by notifying the state’s 811 One Call center, prompting registered utility owners to mark their underground facilities within the excavation zone. The national 811 system serves as a notification network, linking excavators, contractors, and participating utility companies to mitigate excavation risks.

Despite compliance with 811 regulations, the contractor was aware of an unmarked storm drain system within the worksite. Without an accurate map or confirmation of its exact location, the excavation posed significant safety and operational risks. Because not all utilities are registered with 811, additional private utility locating services were required to ensure complete site mapping before excavation commenced.

GPRS Solution: Advanced Utility Locating Technologies

GPRS typically employs video pipe inspection (VPI) to scope, survey, and map storm water systems. This process utilizes remote-controlled CCTV crawlers and push-fed sewer scopes equipped with sondes, which transmit signals that can be tracked to find underground pipelines and identify structural defects like cross bores, inflow/infiltration, and blockages.

However, due to clogged storm drain manholes at this site, standard VPI methods were not viable. Instead, Fernandez leveraged ground penetrating radar (GPR) to conduct subsurface scanning.