Title
Sanitary Sewer Design Standards and Stormwater and Grading Design Standards Update
Body
RECOMMENDED ACTION (Motion):
In preparation for submitting Resolution(s) to revise the Sanitary Sewer Design Standards and revise the Stormwater and Grading Design Standards, staff will present an overview of the proposed updates.
BACKGROUND:
The Sanitary Sewer Design Standards were last updated in 1993. Similar to the Water Standards recently adopted, the Public Works Department compared the sanitary sewer standards to other design documents within the City, other codes in other cities in the region, and ensured consistency with current practices and materials now used in the industry. These revisions to the standards were presented to the Development Stakeholders Group on May 9 and were emailed to area consultants in April for comment during the month of May. The Public Works Department incorporated comments by others which included a few comments from consultants as well as comments from Water Environment Services. The Operations Division of Public Works has also completed a review of the standards to ensure they are consistent with their operations today.
The Stormwater and Grading Design Standards were completely updated in 2015. These standards changed the way we look at stormwater since the previously adopted standards of 1999. The previous standards contained a stormwater standard called Peak Flow. Peak flow considers rain events at the worst time of the event occurring. Calculations were based on a moment in time when the peak of the event occurred.
The 2015 update changed the way we look at stormwater to what is called Flow Duration. This calculation considers the duration of the event rather than the moment in time that the 1999 standards considered. Since using the 2015 standards, staff and consultants have found parts of the standards which are not clear to everybody or provide clear direction on how to address these standards consistently and effective...
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