A new top, a wider spillway and broader base will be added to the Lake Alvamar dam during the coming year, fortifying flood protection for a major road, a state highway and recreational complex downstream.
King’s Construction Co. Inc. will handle the $1.4 million job to upgrade the dam, adjacent to the Jayhawk Tennis Center, 5200 Clinton Parkway. The vegetation-covered clay regulates the speed and amount of water flowing under Clinton Parkway, the South Lawrence Trafficway and through a nearby municipal recreational complex.
Work on the dam is expected to begin in the coming weeks and be finished next fall, in time to allow the watershed lake to start holding water again. The lake effectively has been dry since 2007, when it was drained for repairs but not allowed to refill because of safety concerns.
That’s because ongoing construction of homes, parking lots, roads and other hard surfaces upstream had led regulators to reclassify the dam as a “high hazard” structure, one requiring additional safeguards against dangers that weren’t present when the rural dam originally had been built to manage the flow of Yankee Tank Creek.
Upstream from the dam is the Lake Alvamar subdivision, site of a number of high-end homes, including one valued at more than $1 million overlooking the lake. Some vacant lots along the water command values of $200,000 or more.
Construction throughout the broad drainage area upstream has sent more water moving faster into the lake, said Dick Stuntz, general manager of Alvamar Golf and Recreation Facility and a member of the Wakarusa Watershed Joint District No. 35, which is in charge of the project.
Because culverts beneath Clinton Parkway and the trafficway were designed and built with the dam in place — but before the significant development upstream — upgrading the structure became a priority, Stuntz said.
Nearly three years ago the U.S. Department of Agriculture’s Natural Resources Conservation Service agreed to spend spent $230,000 to come up with a plan for upgrades.
Now, the federal government is pumping $1 million into the contract with King’s Construction to:
• Double the width of the dam’s auxiliary spillway, and strengthening it by covering the spillway with concrete or rock.
• Broaden the base of the dam into portions of This Field and That Field, two former ball diamonds that had been managed by a previous owner, Sport2Sport.
• Add 6 feet to the top of the dam itself.
To make the dam stronger and taller, crews will use clay removed while widening the spillway, said Dale Ping, an estimator for the Oskaloosa-based firm. Bulldozers, backhoes, dump trucks and other equipment will be on site into the fall, with crews working some Saturdays to get the lake back into working order.
“We should be done in the fall,” he said.
While the bulk of project expenses will be covered by the federal government, several local sources also are being tapped. Among them:
• A benefit district that includes Alvamar and about 30 other owners of property around and above the lake, $180,000.
• City of Lawrence, $50,000.
• Douglas County, $50,000.
Other contributors include the Kansas Water Office, Kansas Athletics Inc., the Kansas Department of Transportation and the watershed district itself, Stuntz said.
“If the dam is not adequate … there is a chance for a great loss of property and a loss of life,” said Stuntz, who noted that expanding culverts beneath the trafficway instead would have been expected to cost up to $10 million.