Memorandum 10-66 Storm Water Plan

MEMORANDUM 10-66

TO: Mayor Hornaday and Homer City Council
THRU: Walt Wrede, City Manager
FROM: Rick Abboud City Planner,
Julie Engebretsen, Planning Technician
DATE: May 3, 2010
SUBJ: Ordinance 10-26

Introduction
The City of Homer enacted requirements for storm water plans in 2004. Over the years, permit applicants and staff have noticed some small problems. This year, planning staff presented some housekeeping amendments to the Homer Advisory Planning Commission. The Commission conducted a public hearing on April 7th, 2010, and forwarded the ordinance to the council for consideration.

Summary of Changes
This ordinance makes the following changes to current code:
1. Requires all (rather than only part) of the storm water plan to be prepared by a civil engineer.
The existing code is written in a way that makes it seem an engineer is only needed for one section of the storm water plan. However, in practice, every storm water plan to date has been fully prepared by the engineer because they are required to sign off at the end of the project that the storm water work was done correctly and the plan will work as intended. Rather than having the requirement for an engineer buried in code, this new code language alerts applicants up front that they must hire an engineer.

2. Specifies the storm water event that must be designed for. When designing a storm water plan, an engineer needs to know how big a storm to plan for. There are two variables: duration and magnitude. The duration is measured in hours; how many hours will it be raining hard? Magnitude is measured in years – is it the biggest storm in 100 years? Ten years? There is published NOAA data, called “rainfall frequency maps” that estimate how much rain will fall in storm. To have useful code, code must state what storm event should be designed for. The standard that has been used is the 10 year 3 hour storm, although code was unclear. This ordinance amendment clarifies that the 10 year 3 hour storm will be used, and that is calculated to 0.5 inches per hour.

3. Section 3 of the ordinance completely repeals current code and creates new code.

A. Requires a civil engineer to submit an estimate of how much it will cost to install the storm water plan improvements. Current code requires a cost estimate, but does not state who shall figure the costs out. The cost estimate is used to determine how much money must be bonded. It’s important that an accurate unbiased figure be provided to the city.
B. Allows the use of escrow funds rather than requiring a bond. Staff has found for smaller projects, an escrow account is a simpler way for a developer to meet the financial obligation requirements. The ordinance also exempts storm water plans costs less than $7,500 from the bonding or escrow requirements.

C. Increases the bonding or escrow amount from 100% of the installation cost, to 150%. Several years can pass from project permitting to completion, and costs always rise. Should the city have to arrange for a storm water plan to be installed, there needs to be enough money to cover the costs.

D. Clearly states the engineer must provide written documentation that the storm water plan was installed in a way that meets the mitigation methods. This is a current requirement in code, but not written clearly. The new code language clarifies what the engineer needs to do, and that the city will then release the bond or escrow funds.