The City Center parking lot in Kimberling City, Mo., was repaved using Belgard's Aqualine L and Holland permeable pavers in Gascony tan and red. Stormwater collected by the pavers is filtered and released directly into Table Rock Lake.

 

The aggregate system is layered with four inches of three-quarter washed and cleaned stone, then three-inch stone, and finally a two-inch setting bed of 3/8-inch paved chips. The filtration system is expected to capture eight pounds of nitrogen, 1.5 pounds of phosphorous, four pounds of metal, and 125 pounds of soil and minerals per year, keeping them out of the lake.

Missouri native Layne Morrill grew up canoeing, fishing and swimming on Table Rock Lake in Kimberling City, located in the Ozarks near the state's Arkansas border. The lake's 856 miles of shoreline provide residents like Morrill countless hours of recreation and ensure area businesses revenue through the tourists that visit the lakeside towns each year. When Morrill, who since 1968 has co-owned a retail shopping center adjacent to the lake, learned that installing a permeable interlocking concrete pavers (PICP) parking lot could play a role in protecting the lake's water quality while improving his real estate investment, he endorsed the idea immediately.

"I knew I had seen permeable pavers before, but had no idea what they did until we sat down to talk about renovating our parking lot," said Morrill. Along with his five other co-owners, he had considered alternate surfaces for the three-acre, 30-year-old parking lot of Kimberling City Center, which serves the community's post office as well as a hotel, church, condominiums and various retailers and restaurants. Gopala Borchelt, executive director for the nonprofit water quality organization Table Rock Lake Water Quality, Inc., brought together the ownership group with Belgard Hardscapes, an expert in PICP solutions. Belgard representatives met with the owners, explaining PICP as a system of pavers over layers of aggregate that filters stormwater running off the parking lot down between the pavers and through varying sized stone. The aggregate cleans the water, which can be stored temporarily in an underground storage basin before being released to natural aquifers or, as in the case with Table Rock Lake, released directly back into the lake.

"Needless to say, we were impressed with permeable pavers and said "yes' unanimously on the spot," Morrill said. "Anything that we can do that will improve water quality, fix the parking lot, and showcase our property is a winning solution."

Before the introduction, Borchelt had done considerable research, including traveling to different sites around the region and considering comparable projects. She learned that based on studies of similar types of paver systems, the PICP system at Kimberling City Center was estimated to capture roughly eight pounds of nitrogen, 1.5 pounds of phosphorus, four pounds of metal (iron, copper, lead) and 125 pounds of soil and minerals per year, which otherwise would compromise the lake's water quality.

Paving installation machines from Aqua-Paving Construction can lay more than 1,000 square feet of pavers per hour. The three-acre parking lot was fully repaved in about 130 hours.

When the installation was complete, Kimberling City fire authorities demonstrated the permeable paver system by showering the parking lot with a fire hose as spectators looked on. The permeable pavers will help keep the lake water clean for years to come.

"Water quality is a very important issue," Borchelt said. "People live here, visit here, and move here for the White River Valley. We didn't want to just talk about it. We wanted to do something that would protect the lake better than it had been in the past."

She also looked at alternate surfaces.

"We didn't want to use porous asphalt or pervious pavement because of the labor and equipment needed for installation, and both are high maintenance," said Borchelt, noting that other surfaces require repair or replacement every four years whereas Belgard Hardscapes PICP promotes a 50-year pavement design. "We also needed to be able to keep the parking lot accessible during installation because the tenants need their businesses open. Pavers let us do that."

Permeable interlocking concrete pavers can be installed by a machine, and installer Aqua-Paving Construction was able to lay more than 1,000 square feet of pavers per hour at Kimberling City Center. AquaPaving compacted the paver surface with a 7,000-pound plate compactor and swept chips into the openings between the pavers that will allow the water into the system.

The aggregate system includes three-inch stone under four inches of three-quarter stone that has been washed and cleaned; the washed rock helps water pass through the aggregate, removes contaminants and returns the clean water to the groundwater. AquaPaver Construction then laid a two-inch setting bed of 3/8-inch paved chips and laid the pavers on top of that.

"A permeable paver system ensures less contaminants enter the water than when water washes off an asphalt parking lot, and the water enters the lake at a cooler temperature," said Dave Farrero, field superintendent with Aqua-Paving.

Stormwater runoff from asphalt enters streams and lakes at elevated temperatures, which can be harmful to aquatic life. In the late 1990s, Table Rock Lake suffered an algae bloom in the James River arm of the lake, and experts say stormwater runoff contributed to the problem. It is a problem that hasn't been forgotten; a recent public survey by Ozarks Water Watch of residents in the Upper White River Basin indicated the largest concern to the public in the Table Rock Lake area is stormwater from development. By using a PICP system that accepts runoff down into the stormwater system and discharges it into the lake at a reduced temperature, Kimberling City Center's owners took action to ensure the lake retains its pristine appearance.

"We plan to utilize this highly visible location to not only help protect water quality and improve the overall appearance of the community center, but also as a demonstration site for other local businesses and municipalities to learn from," said Borchelt. "So developers have the option of replacing old, worn-out pavement areas or creating new areas in a way that reduces the negative impacts on surrounding hydrology and water quality."

The plans to retrofit an existing infrastructure with newer, best management practices for stormwater management helped the Kimberling City Center project qualify for an EPA 319 Grant from the Missouri State Department of Natural Resources, making the project more cost effective for the owners, who also gained the benefit of a parking lot that is as beautiful as it is functional.

The paver design included Belgard Hardscapes' Aqualine L in both Gascony tan and red, complemented by Belgard's Holland in the same shades in the crosswalks and soldier course around curbs, islands and bioswales.

"It's just gorgeous," said Morrill. "One of the best things about the new parking lot is the mental attitude – how proud we are to have done something that no one else around here has done."