OTTUMWA — Rain drops speeding across the Bethany Baptist Church parking lot will hit a slow zone by next year.

Located at 201 McKinley Ave., Bethany Baptist Church is not only in a bend of Kettle Creek but also has a large roof and parking lot. Across the street are four homes with large roofs.

All that adds up to a lot of moving water when it rains.

Jennifer Steffen is the watershed coordinator with the Wapello County Soil & Water Conservation District. She said the church has agreed to a rain garden structure and a crew began work Monday morning on one side of the “green space” area on church property.

Those working on the project include the Wapello County Soil & Conservation District, the city of Ottumwa and Bethany Baptist Church. The city workers on site were part of a sewer crew.

Steffen said workers will strip the dirt for the rain garden structure, which will be 184 feet long and 10 feet wide. When finished the structure will be parallel to and just as long as the church’s parking lot.

“[The rain garden] is designed to capture the runoff from impervious areas, such as concrete,” she said. “There’s 27,000 square feet of impervious area here.”

The rain comes down the roof and joins the runoff flowing across the concrete parking lot. After the rain garden is ready, those drops will leave the concrete and encounter the rain garden and the obstacles, or “slow-downs” the structure provides above and below the ground.

“We’ll also have a berm on the downhill side and a seven- to nine-inch ponding area where the rain drops will gather and percolate down through,” Steffen said.

Below ground, there will be layers of specified soil mix, native/natural soils, washed concrete sand and a foot or so of washed rock and subdrain.

Steffen said workers will put in 1 1/4-inch layer of rock, followed by layers of coarse sand, then sand mixed with compost. There will also be a pool below that will slow down the rain going through the storm sewer and across the street to Kettle Creek.

“On the very top of the rain garden, we’ll have native grasses,” Steffen said. “Later, the Wildwood School students will help us plant 1,840 ‘plugs.’”

Plugs are small plants about 1-2 inches wide and 4-6 inches long.

“This is a wonderful green space here,” Steffen said as she watched Robin Fitzsimmons use a track hoe to break ground for the rain garden.

Kettle Creek originates 1.5 miles south of Ottumwa and travels north and east through the city. It empties into an oxbow lake in Ottumwa Park. The creek’s watershed is 1,048 acres and it drains 633 acres of agricultural land and 415 acres of urban land.