Three stormwater treatment technologies were tested for effectiveness in removing pollutants from boatyard stormwater in a pilot study, the results of which are presented in The Boatyard Stormwater Treatment Technology Study (Taylor Associates 2008).
Cost estimates for each technology were developed to help determine if they should be considered as “all known, available and reasonable methods by industries and others to prevent and control the pollution of the waters of the State of Washington” (this statutory requirement is generally known by an acronym – AKART). This report presents order-of-magnitude capital and operation and maintenance (O&M) cost estimates necessary for an AKART determination by the Washington State Department of Ecology (Ecology).
In order to develop a common basis of costing, a typical boatyard was considered to be two acres of flat, impervious surface with one stormwater outfall. Based on a survey of boatyards, the typical boatyard does not have all necessary infrastructure in place to
effectively collect stormwater. The following four cost estimates were developed:
- StormwateRx® Aquip™ capital and O&M costs
- Siemens Water Technologies, Inc. Wastewater Ion Exchange System (WWIX) capital and O&M costs
- Water Tectonics, Inc. Wave Ionics™ Electro-Coagulation System capital and O&M costs
- Drainage improvement and infrastructure capital and O&M costs
A net present value (NPV) analysis was performed based on 15-year project life. The results of the NPV suggested that StormwateRx® Aquip™ and the electrocoagulation systems had similar NPVs of approximately $220,000 to $230,000 for a typical 2-acre boatyard. The Siemens Water Technologies WWIX system NPV was over three times the cost of the other two technologies. Site improvements for a typical 2-acre boatyard are estimated to contribute to approximately one-half of the total cost to install and operate a stormwater treatment technology.