A 35-year-old woman from Coulterville, identified Wednesday by Calaveras County authorities as Twyla Capurro, was the person killed during a Tuesday afternoon collapse at the under-construction Canyon Tunnel Project outside Knights Ferry.
The incident was called in as a rescue response to Modesto Fire Department at 3:42 p.m. Tuesday, April 14, according to the department’s daily log of incidents.
The site of the Canyon Tunnel Project, being jointly constructed by South San Joaquin Irrigation District and Oakdale Irrigation District, is near Schell and Sonora roads, at the Stanislaus-Calaveras county line.
According to Modesto Fire officials, Engine 29, Quint 18, and Battalion 2 were dispatched for a possible tunnel collapse in the Knights Ferry area. E29 requested a technical rescue response while they were still responding, which brought Engines 1, 11, 21, 23; Squad 32; Rescue 11; Trucks 1, 5; Battalion 3; and Medic 1.
“E29 was the first to arrive and advised that three people were unaccounted for in a tunnel,” the department incident log states. “E21 arrived on scene and assumed Incident Command.”
After completing an assessment of the situation, responders “determined that one individual remained trapped in the tunnel, one had self-evacuated without injury, and another was rescued by coworkers, sustaining moderate injuries.”
Crews made entry and determined that the trapped individual was deceased. Cal-OSHA and Calaveras County Sheriff’s Office personnel were also conducting an investigation. Crews remained on scene and assisted with the recovery once the scene was secure, removing the victim about 10 p.m. Tuesday.
Authorities indicated Capurro worked for Provost and Pritchard, which was listed as the engineering and design firm for the project.
Officials reported the collapse – with the cause yet to be determined – occurred about 200 feet inside the tunnel.
According to information on the South San Joaquin Irrigation District website regarding the project: “Together with its partner Oakdale Irrigation District (OID), South San Joaquin Irrigation District (SSJID) is constructing a bypass tunnel for its Joint Supply Canal (JSC). The project, currently referred to as the “Canyon Tunnel Project,” would increase water delivery reliability into the next century.”
Also posted on the SSJID website is a recently released video providing a spring update on the project, which details the work currently being done at the site. The firm Drill Tech Drilling & Shoring Inc. is the main contractor working on the tunnel portion of the project.
It is an $80-plus million project being built on private property, according to the SSJID, with that district covering 72 percent of the cost and OID covering 28 percent. There will be 12,000 feet of new tunnel, the project plan indicates.
