Posted on September 15, 2020
Water treatment facility nearly lost in Aug. 15 flooding
Chesterfield County’s Utilities Department is building a flood wall to protect its Addison-Evans water treatment plant on the Swift Creek Reservoir, which has been severely damaged by flooding twice in a two-year period – most recently less than a month ago.
The department has applied for a pre-disaster mitigation grant from the Federal Emergency Management Agency that would cover 75% of the project’s estimated $11.56 million cost.
“We’re confident we’re going to get approved for the grant,” said George Hayes, the county’s utilities director, in a recent interview.
The Utilities Department submitted its application in October 2018, about three weeks after Tropical Storm Michael flooded the Addison Evans plant and caused more than $600,000 in damage to pumps and electrical equipment located in the basement.
One year later, FEMA requested additional information – specifically, an environmental assessment and hydraulic modeling – regarding the proposed flood wall.
A consultant hired by the Utilities Department began that work last month, just before a low-pressure system stalled over Chesterfield and dumped 8 to 12 inches of rain across the county on Aug. 15, causing what the National Weather Service classified as “700-year flooding.”
The basement of the Addison-Evans plant was completely inundated again. As utilities staff cut power to the facility and evacuated by boat via the rapidly rising reservoir, floodwaters also were pouring through the windows of first-floor offices 11 feet off the ground.
“Most of us talk in terms of a 100-year flood or 500-year flood in terms of purchasing flood insurance. That’s the first time I’ve heard of a 700-year flood. It was a major, major event,” said Loy Senter, chief of Chesterfield Fire and EMS, during a presentation at the Board of Supervisors’ Aug. 26 meeting.
Leslie Haley, the board’s chairwoman, said Chesterfield came “pretty darn close to losing one of our [water treatment] plants.”
Built in 1967, Addison-Evans provides 12 million gallons of drinking water per day, or about 20% of Chesterfield’s total supply.
The county gets about 55% of its drinking water from the Appomattox River Water Authority plant on Lake Chesdin and purchases 25% of its water from the city of Richmond.
The initial countywide damage estimate from the Aug. 15 storm was about $2.8 million. That figure is expected to increase, according to Jessica Robison, Chesterfield’s interim emergency management coordinator.
Hayes predicted damage to the Addison-Evans plant, which remains shut down indefinitely, will be more extensive than what it sustained in 2018.
“We had not seen flooding like that prior to Tropical Storm Michael,” he said.
Scott Morris, an assistant utilities director, told the Board of Supervisors last month that staff are in the process of evaluating the facility for repair and replacement of parts.
“There is some equipment that has a long lead time, so we’re trying to figure out strategically if it’s worth replacing equipment that’s at the end of its useful life. We may do an extended shutdown to allow us to bring the facility back in a better condition than when we left it on the morning of Aug. 15,” he added.
Meanwhile, work continues on the flood wall, which will be built on the banks of the Swift Creek Reservoir with nearly 2,000 linear feet of reinforced concrete.
The wall’s height has not yet been determined, although Hayes acknowledged it will increase as a result of the historic flooding last month.
“We have to make sure it’s taller than the highest point of the water. From an engineering standpoint, it’s good that we have that data,” he said.
FEMA is expected to award the pre-disaster mitigation grant next July. It would cover 75% of costs related to design ($1.44 million) and construction ($10.12 million), as well as reimbursement of more than $550,000 the county has incurred from performing the environmental assessment and hydraulic modeling.
If the grant is approved, the flood wall will be completed in either late 2023 or early 2024.
The local share of the cost is estimated at $2.89 million. Jeff Franklin, assistant utilities director for finance and administration, noted the project has been included in the Utilities Department’s 10-year capital improvement plan and its rate model since 2018.
“The rate model provides for rates and fees to be spread out over time, preventing rate spikes to our customers. This project utilizes reserves and fees that have already been accounted for in our current rates,” he said.
In retrospect, Hayes says the county made a mistake 53 years ago by building the Addison-Evans plant in the floodplain of the Swift Creek Reservoir.
“In the 1960s, water treatment plants were located as close to the supply as possible,” he said. “Today we have better data and hydraulic analysis to know where floodplains are and to stay out of them.”
Source: chesterfieldobserver
