5.8.2 Langdon Lake Wetland Detention Pond

ProjectLangdon Lake Wetland Detention Pond
DescriptionConstruction of a stormwater treatment pond at the former wastewater lagoon site. If an alum injection system is selected as one of the strategies to control internal loading, this pond could serve as the floc settling basin.
Need

The phosphorus reduction plan for Langdon Lake requires a reduction of 99 pounds of phosphorus per year from external sources. A wet detention pond is proposed for consideration at the former wastewater lagoon site, which drains subwatersheds LL-1 through LL-4 and part of LL-5. It would be sized to remove 50 percent of the incoming load. The estimated project cost assumes there would be no land acquisition cost as the necessary land is currently publicly owned.

If an alum injection system is constructed as the preferred internal load management option, then this pond would be necessary to serve as the floc settling pond, although that project if constructed by itself would provide some treatment for runoff from the subwatershed.

OutcomeThis pond could remove an estimated 45 pounds of phosphorus annually, along with other pollutants such as sediment.
Estimated Cost and Funding
Investigation, permitting, construction, and project
management. Funding source is the District capital levy.

$103,400 Design

$698,300 Construction

$801,700 Total

Schedule

2012 Design (in concert with internal management/alum injection)

2013 Construction (in concert with internal management/alum injection)