20160906AVU to Staff 139.doc

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION

JURISDICTION: IDAHO DATE PREPARED: 09/01/2016
CASE NO.: AVU-E-16-03 WITNESS: Karen Schuh
REQUESTER: IPUC RESPONDER: Rod Staton/Vance Ruppert
TYPE: Production Request DEPARTMENT: Facilities
REQUEST NO.: Staff - 139 TELEPHONE: [phone]

REQUEST NO.:

For the two swales constructed on the Avista corporate campus, please provide a listing of all expenses associated with the construction, and the accounts to which they were booked. Please also describe the necessity and benefit of the swales.

RESPONSE:

Swale #1 will refer to the swale located on the north side of the corporate campus along Upriver Drive, next to N. North Center St. Swale #2 will refer to the swale on the south side of the corporate campus along Upriver Drive, next to Mission Ave.

Swale #1 - The necessity of this swale was to treat and filter storm (rain) water runoff that lands on the corporate campus’ asphalt surfaces, so that untreated oils and chemicals that are inherently part of asphalt do not run off with the rain water into the city storm water system, or worst case into the Aquifer or Spokane River (directly adjacent to campus). It also filters the dirt and debris that gathers through normal use on asphalt surfaces and also makes sure they do not run off with the rain water either. Swales are required through the State of Washington and City of Spokane regulations (Department of Ecology, etc.) in order to install asphalt on any new developments with asphalt, and does not pertain just to Avista. The design plans for the Swales are approved by the city of Spokane. Please see Staff_PR_139 Attachment A for cost detail of Swale #1. The majority of the costs associated with this swale are related to the excavation costs, as this swale is much larger than Swale #2.

Swale #2 - The main Avista campus is adjacent to the Spokane River. Two buildings on the main campus have large roof surface area. During storm events the roofs drain directly into the Spokane River. In the same pipe, directed at the river is the out flow from our front cooling pond. The 100,000 gallon pond has to be emptied and cleaned monthly during the summer months. A permit was obtained from the Washington State Department of Ecology for the purpose of draining the pond water into the river. The permit was renewed yearly and cost several thousand dollars. Swale #2 was designed to treat the roof drain water and the pond water through bio filtration. Flora designed to pre-filter the water as it sits in the swale was included in the design. The pipes that drained to the river were permanently plugged. All roof storm water goes to the swale now. This swale is a natural alternative to directing storm water into the river directly. The swale construction will result in reducing the potential liability associated with the pipe that flows directly into the Spokane River, and preventing the particulate matter that settles on our roofs from draining directly into the river. Please see Staff_PR_139 Attachment B for capital costs incurred to date for Swale #2. The majority of the costs associated with this swale have to do with the pump system that was installed in order to pump the water from under Upriver Drive into the swale.

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