City Council Meeting - FINAL

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Meeting Date: 11/01/2022  
From: Edward Schenk, Water Services Manager - Stormwater

Discussion on Stormwater Credit Manual Revisions
Staff recommends accepting the proposed revisions to the Stormwater Credit Manual and seeks direction from City Council to formalize those revisions.
The most recent Stormwater Credit Manual was instituted in 2015. No amendments been made since.

A detailed review of the Stormwater Credit Manual reveals potential inconsistencies with the original intent of the manual. Concerns exist about the current Stormwater Credit Manual's provision of incentives to Flagstaff residents. The intent of this discussion item is to provide Council with the ability to review Staff recommended revisions to the Credit Manual. If approved, Staff will move forward with an ordinance to create an updated Stormwater Credit Manual for 2023 and the future. Such an ordinance would require the standard two public readings at subsequent City Council Meetings.
The most recent Stormwater Credit Manual went into effect in 2015. It is a revised version of the original Stormwater Credit Manual of 2006 and was intended to provide incentives to businesses and property owners to "go above and beyond" in their private stormwater infrastructure. The current Stormwater Credit Manual contains language that could pose possible concerns with its application. The subject of revising the Stormwater Credit Manual was briefly mentioned to Council as part of the initial City Council discussions related to the Stormwater Rate Study. Additionally, this item was formally presented to the Water Commission in September. A summary of the proposed changes are below and are also in the attached draft updated Stormwater Credit Manual. If the draft document is accepted by Council it will be put forward in ordinance form with the required two public reads at future regular City Council Meetings. 
Stormwater Detention:
In particular: the current Stormwater Credit Manual provides a 20% credit for detention of the 2, 10 and 100 year events. This must be clarified as these standards are required by current code.
The Stormwater Credit Manual provides a 9% credit for meeting detention code of the 1990s. This must be clarified to be consistent with the current detention requirements of the updated/current drainage code.
Staff recommends removing both credits and replacing with a 10% credit for detention basins that provide detention beyond current code. Specifically a detention requirement for a 500 year event.
Residential Water Harvesting:
The Stormwater Credit Manual currently provides a 10% credit for a minimum of 2 rain barrels with a combined capacity of 100 gallons on a residential property. Staff recommends this be changed to a minimum of 300 gallons of on-site residential rainwater harvesting. This change is intended to show a real benefit in terms of rainwater runoff reduction while not being too difficult to obtain for a typical property owner.
Conservation Easement:
The Stormwater Credit Manual provides a 10% credit for a minimum of 10 contiguous acres of conservation easement. This requirement will be hard to meet within City limits as open parcels become more rare, and more expensive. It is recommended that this be changed to 2 contiguous acres of conservation easement for the 10% credit.
Structured Educational Program:
No change.
Additional change to the Credit Manual:
Addition of a section for floodproofing, provide a 10% credit for "wet" or "dry" floodproofing of the primary structure(s) on a parcel.
Draft Credit Manual
Existing Credit Manual


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