Diving into Dam Maintenance

Story and Photos by Rick Benoit, Distict Dive Safety Officer

By the numbers, nine projects visited, 19 dives executed, 10 missions completed, 10 days worked, 1,000 miles traveled. These highlight November’s first-ever mobilization by the USACE Forward Response/Technical Dive/ remotely operated vehicle (ROV) Team to Walla Walla District.
In total, the USACE team; comprised of members Thom Stan of Walla Walla, Todd Manny, Terry Vance and Rick Benoit of Portland, Steve England of Philadelphia and Eric Lockington St. Paul Districts, safely completed eight jobs diving, one task utilizing a ROV and another where a diver did not need to get wet.
“This was an exceptional opportunity for our group to demonstrate our comprehensive toolbox of capabilities,” said Benoit, the team’s Dive Safety Officer and Program Manager. “This mission was extremely diverse and challenging as we needed to perform a complex ROV / SONAR operation, a challenging mechanical repair and a series of intricate inspections by boat and by land.”
During the two week mobilization, the team executed a two-day ROV / SONAR inspection of the Removal Spillway Weir at Lower Granite; a National Highway Administration (NWHA) certified inspection at the Lower Granite Construction Bridge and the Chief Timothy Park Access Bridge in Clarkston. Additionally the team replaced a dysfunctional irrigation intake at Swallows Park in Clarkston as well as performed irrigation intake pipe inspections at Skookum, 55-Mile, Lost Island and Big Flat Habitat Maintenance Units (HMU’s) along the Snake River.
“Inspecting the RSW with SONAR and a ROV is a great opportunity to accomplish quality work underwater without needing to use divers or to put divers at risk,” explained Manny, NWP’s Program Manager for ROV operations. “Because of the complexities of diving this large structure and the risk of entanglement to divers, this was a perfect situation to use our ROV.”
The team used its ROV / SONAR equipment, which according to Manny cost about $200,000, to evaluate the 10-year old RSW’s structural integrity and survey for debris such as logs and trash which interfere with the unit’s function of assisting fish pass thru the dam spillway.
“Our Swallows Park job to me was by far was our most challenging and rewarding mission,” said Benoit who serves as the Walla Walla and Portland District’s Dive Coordinator. “There’s nothing like rooting thru 10 feet of silt and working in pitch black water to fix a problem using only your instincts and sense of touch.”
Unable to use lights due to black-water conditions, divers were required to locate a pipe connection burred in 10 feet of mud, cut thru the 12-inch wide, half inch thick pipe using a hand-saw, dig a 30 foot trench with an air hose and reconnect new pipe and fittings during the team’s two days at Swallows Park.
“One of the most memorable parts of our mission was the look of relief on Rick’s face when we finished the Swallows Park job,” said team Professional Engineer (PE) Steve England, a civil engineer from Philadelphia District.
Clarkston Natural Resource Management Office Operations Project Manager Jamie Howard called the Swallows Park mission efficient, professional and safe, as well as it illustrated “Great team work from across USACE Districts and Divisions, a dedication to work until the mission was accomplished.”
Highlighting this mission’s inter-District and Division collaboration were its underwater bridge inspections which required execution in accordance with the USACE Bridge Safety Program and its Engineering Regulation (ER) 1110-2-11. To comply with Federal Highway Administration (FHWA), Army Corps regulations and National Bridge Inspection Standards (NBIS), the team comprised of certified underwater bridge inspectors from USACE Districts in the Northwest and Northeast; Portland and Philadelphia.
Accordingly, all underwater structural surveys will be conducted while directly supervised by a qualified bridge inspection team leader and performed by certified underwater bridge inspection divers every 60 to 72 months or as required by the structure’s condition.
“Bridges must be surveyed according to National Bridge Inspection Standards (NBIS) and USACE has a limited roster of qualified divers to accomplish this mandatory task,” said England who served as the bridge inspection’s certified FHWA Team Lead. “These bridge inspections are a great example of how we can reach across Districts and Divisions to get the job done appropriately according to regulation.”
Benoit and NWP Deputy Dive Coordinator and ROV Program Manager Todd Manny rounded out the team of

Diver tender Todd Manny performs an equipment check on diver Marty Crosson prior to beginning the flowering ruch mitigation dive mission at McNary Beach, Aug. 15, 2015. Photo by Rick Benoit

Diver tender Todd Manny performs an equipment check on diver Marty Crosson prior to beginning the flowering ruch mitigation dive mission at McNary Beach, Aug. 15, 2015. Photo by Rick Benoit

After five dives and 156 minutes underwater, USACE Forward Response Technical Dive Team member Todd Manny (from the Portland District) is assisted back on board the day’s work vessel by his teammate, Buffalo District’s Marty Crosson.  Photo by Rick Benoit

After five dives and 156 minutes underwater, USACE Forward Response Technical Dive Team member Todd Manny (from the Portland District) is assisted back on board the day’s work vessel by his teammate, Buffalo District’s Marty Crosson.
Photo by Rick Benoit

certified and qualified divers who performed underwater and above-water inspections on the Construction Road Bridge at Lower Granite Dam and the Chief Timothy Park Access Bridge in Clarkston, Wash.
“With limited recreation budgets, using the in house dive team was cost effective for these shallow dives that don’t require a (recompression) chamber or a need for contracted commercial divers,” said Marty Mendiola, who as the Lower Granite Operations Project Manager oversees Swallows Park, as well as the two bridges which span the Snake River. “In addition, these maintenance activities generally run into unexpected conditions. Modifications are much easier with an in house crew (assuming the change is within capabilities of the crew) versus a contract modification that would take more time and money.”
Initially, weather greatly assisted the Bridge and Swallows Park missions with unseasonably mild temperatures in the 50’s, calm winds and smooth water. However, week two was not so kind when the team performed its underwater irrigation intake pipe inspections on the Snake River between Ice Harbor and Little Goose dams as temperatures plunged to below freezing with wind chills near zero.
In all, five inspections were performed at four HMU’s managed by Ice Harbor Dam’s Natural Resource Office; three of the Snake River dive sites needed to be accessed from land due to poor weather. One site, 55-Mile HMU, was accessed by boat.
“This was by far the most interesting albeit coldest part of our mission,” said dive tender Terry Vance. “Interesting because we were traveling to and diving in water surrounded by some of the most rugged but beautiful scenery the Snake River offers. Unfortunately, the area’s beauty did not make up for how cold it was.”

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