2012-08-27_PWETC_Minutes - Laserfiche WebLink

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Chair Vanderwall concurred that a better explanation and definition would be helpful; with Mr. Leaf concurring, and suggesting that some graphics may also help in that explanation. With Mr. Leaf explaining the calculations in determining those freeboard elevations, Member DeBenedet opined that he wasn't confident that they were all that conservative. While there was always the potential that a rainstorm would exceed those estimates, Member DeBenedet opined that once the new storm design numbers were released next spring that would become even more evident. Ms. Bloom advised that this challenge had been a discussion internally, regardless of changing a table to comply with new rules; and current infrastructure designed around previous designs storm numbers and concepts. Ms. Bloom opined that the challenge was the ripple affect; creating the need for an updated plan. Ms. Bloom advised that enforcing freeboard calculations with existing numbers created no compliance issues; however, with the new numbers, it created a lot of issues in the community; and would need considerable review. At the request of Chair Vanderwall regarding creating liability issues for the City, Ms. Bloom noted this was why staff was currently hesitant to address the issue at this time, since there were bigger policy issues once those numbers were published. Member Stenlund noted the "grandfather clause" and differing rules based on which plan was in effect at a given time; and making sure future plans are well aware of the updated data. Discussion ensued regarding 100 year events; emergency overflow (Item 6) and undeveloped modeling at this time; and designing of facilities based on best available information at the time. Based on liability concern issues, Member DeBenedet suggested, with review and approval by the City Attorney, that Policy #6 be revised to read: "For newly constructed storm water retention ponds, the City shall require an emergency overflow spillway to safely convey flows in excess of the 100-year (1% probability) eventJ...to the maximufn extent r efiea le ]" While most lift stations throughout the City work just fine under typical events, Ms. Bloom noted that things, such as mechanical failures, could happen. In response to Chair Vanderwall's question as to whether words become meaningless under practicable application, Member Stenlund noted that "Maximum Extent Practicable" was a legally defined term at the EPA level. Section 4.0 Goals and Policies (page 17) Page 10 of 15