At the first public meeting about a West End flooding study last spring, people learned what dangers lay in store if there was ever another storm like the one that unleashed a huge flood in 1937.
At the second public meeting, set for Nov. 18, people will hear about the detailed alternatives that a team of engineers developed to deal with another flood.
As consultant John Eisen put it, “OK, we've got a problem. What steps can we take to mitigate that problem?”
Based partly on what they hear at the Nov. 18 meeting, the engineers will come up with a final plan that will be reviewed by the Federal Emergency Management Agency and eventually submitted to the Billings City Council and the Yellowstone County Commission for approval.
The study actually looks at two big issues — what to do with floodwaters in the event of a major storm and how to replenish groundwater supplies on the West End.
The alternatives that will be presented at the public meeting range from creating two large impoundment ponds on Cove and Little Cove creeks to building more greenways and diverting the flow of Cove Creek to west of 56th Street West.
Eisen said the engineers deliberately haven't chosen any favorites and are hoping to get further guidance from the public at the Nov. 18 meeting. About 150 people attended the first meeting in April.
The $300,000 study is being funded by FEMA and the state Department of Natural Resources and is being directed by the city-county Planning Department. The lead contractor is PBS&J, a consulting engineering company in Bozeman, with support from two Billings companies, HDR and JGA Architects, Engineers and Planners, the company Eisen is with.
The most recent draft of the study puts estimated price tags on each of the alternatives. The most expensive option, including construction, land purchase and engineering, is the building of the impoundment ponds, estimated at nearly $36 million. The cheapest, more greenway development, would cost about $7.5 million.
That's a lot of money, but floods do a lot of damage.
In June 1937, two days of heavy rain to the west and northwest of Billings filled Canyon, Cove and Alkali creeks to the point of overflowing. There was heavy flooding in large areas of the West End and in the downtown area. More than 3,000 homes and businesses were flooded and one person was killed.
Damages were estimated at $3 million, or nearly $45 million in today's dollars. The big difference is that in 1937, nearly all of the West End, now dotted with houses and commercial development, was agricultural land.
All of the alternatives in the plan were based on high-tech analyses included in a flood-hazard study conducted in 2006 and 2007, also by PBS&J. Using global positioning and light detection and ranging technology, the study created detailed, accurate flood-hazard maps.
The study area takes in 20 square miles, roughly bordered by Shiloh Road, 72nd Street West, Rimrock Road and Hesper Road. There will be newspaper ads announcing the public meeting, and the Planning Department will send personal invitations to some 2,300 residences next week.
At the meeting, there will be exhibits showing details on each alternative, with engineers on hand to answer questions. The alternatives will also be explained in presentations to the whole group, followed by discussions of the alternatives with engineers, consultants and members of the public.
Everyone will be asked to fill out a card listing a favorite and a least favorite alternative, with plenty of room to comment. Here's a quick look at the alternatives:
No. 1: Construction of large storage impoundments upstream of the study area on Cove and Little Cove creeks. This would include embankments to hold back floodwaters, pass-through culverts and emergency spillways. Benefits include a big reduction in peak flood flow rates. Concerns include regulatory issues, land ownership, cost and the need to keep the ponds empty most of the time, so they could always handle major flooding.
No. 2: Greenway development to route floodwater through the area. Benefits would be confining flooding to a better-defined area while creating more open space and bike and foot paths. The main concern is the need to acquire private property from numerous landowners.
No. 3: Greenway development paired with splitting Cove Creek, which would involve routing nearly all of the creek's flood waters to the west of 56th Street West. This would greatly reduce flooding east of 56th, but would increase flooding west of there. Greenways would help reduce the impact of flooding on that area.
No. 4: Greenway development, Cove Creek split and Canyon Creek diversion. This would add to the previous option the creation of diversion channels and pipes to route more water into Canyon Creek. This would do a lot to decrease downstream flooding, but there are concerns about impacts to Canyon Creek and questions as to how much more water it could handle.
No. 5: Greenway development, Cove Creek split and Knife River gravel pit. This adds to alternative No. 3 the reclamation of the old Knife River gravel pit near Shiloh and Hesper roads. This would add storm-water detention capacity and help recharge groundwater aquifers. There are concerns about land ownership, acquisition costs and commitments from the gravel companies.
No. 6: Greenway development, Cove Creek split and Sharptail Pond. This adds to alternative No. 3 the creation of a retention facility at the confluence of Shiloh Drain and Hogan's Slough, at Sharptail Pond. This option would add to water detention and groundwater recharge and create recreation opportunities. Concerns have to do with land ownership and acquisition costs.
Once the final plan is approved, it will be adopted as part of the Yellowstone County Pre-Disaster Mitigation Plan, which is being updated. That process is supposed to be finished by next April.
Project manager Wyeth Friday, with the Planning Department, said funding sources will vary depending on what option is chosen.
Contact Ed Kemmick at firstname.lastname@example.org or 657-1293.