20160906AVU to Staff 133.docx

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATIONJURISDICTION:IDAHODATE PREPARED:08/22/2016CASE NO.:AVU-E-16-03WITNESS:Scott KinneyREQUESTER:IPUCRESPONDER:Mike MagruderTYPE:Production RequestDEPARTMENT: GPSSREQUEST NO.:Staff-133TELEPHONE:[phone]REQUEST:In AVU-E-15-05, the Company estimated Regulating Hydro expenditures of $3.5 million for 2016. This project now has 2016 expenditures listed at $5 million. Please provide a detailed explanation of these costs, particularly the difference between last year’s estimate and the current estimate. RESPONSE:The Company has a 2016 project at the Long Lake HED to mitigate Total Dissolved Gas (TDG) in the tailrace of the dam. In order to complete this project, the entire spillway/tailrace was de-watered exposing the toe of the dam. In addition, an access road was built to the toe of the dam for the TDG work.Inspection of the dam upon de-watering found a large section of rock abutment had dislodged over time due to the force of spilling water. Given the need to add structural concrete to the dam in the void and the opportune timing with the spillway/tailrace de-watered and an access road already constructed, the decision was made to proceed with the structural concrete addition to the dam in 2016.The estimate for this additional work is approximately $2.1M. The Regulating Hydro expenditures have been trending slightly below estimates, so the year end estimate was revised to $1.5M to cover the new concrete addition (estimated over 700 cubic yards of concrete) to the dam.