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TO: Mayor Richard C. Irvin
FROM: Mark Phipps, Engineering Coordinator
DATE: August 12, 2019
SUBJECT:
Resolution to award a contract to HR Green, Inc. in the amount of $74,700.00 for preparation of the Mastodon Lake Stormwater Plan.
PURPOSE:
Develop a plan to improve water quality in Mastodon Lake, reduce flood damages in the surrounding area, create a new recreational amenity for the neighborhood, estimate the cost of these improvements, and identify potential sources of grant funding.
BACKGROUND:
Mastodon Lake was excavated in the 1930s during the construction of Phillips Park. Over the years, sediment and decaying organic matter have accumulated at the bottom of the Lake to an average depth of nearly 2 feet. The average water depth throughout the Lake is now only 2.5 feet. Such a shallow aquatic system is susceptible to warming, excessive nutrients, and becoming overrun with algae and other aquatic vegetation. These conditions are unsightly and limit recreational opportunities, such as boating and fishing. Within the past two years, the City has used an herbicide to control the growth of aquatic vegetation and has vacuumed the sediment near the intake for the Phillips Park Golf Course's irrigation system, in order to protect the pumps. But these are not long-term solutions to the problem.
The limits of the Mastodon Lake floodplain extend west from Phillips Park into an Aurora neighborhood. Dozens of residential and commercial properties in this area are subject to flood damage during extreme storms. Preliminary engineering has shown that the base flood elevation can be lowered significantly by lowering the Mastodon Lake outlet.
A Stormwater Plan for Mastodon Lake would allow the City to accomplish the dual purposes of improving the health of the Lake and reducing the likelihood of flood damages, while also creating a new City park in the open space surrounding nearby Little Doe Lake. The project would involve dredging the Lake, portions of...
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