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HomeMy WebLinkAbout5.a. Approve Plaans & Spec's / Authorize Ad for Bids, Hawkins Pond, City Project #176a DATE: FEBRUARY 25, 1988 TO: MAYOR & COUNCILMEMBERS C/O ADMINISTRATOR JILK FROM: CITY ENGINEER/PUBLIC WORKS DIRECTOR HEFTI RE: ITEMS FOR THE MARCH 1, 1988 COUNCIL MEETING OLD BUSINESS 5a. improve Plans & Specs/Authorize Ad for Bids, City Contract 1988-2 Hawkins Pond Storm Water Improvements Council last considered this item at the February 2, 1988 meeting. Because of Councils concerns regarding the necessity of proceeding with Project #177, the proposed Section 30 Storm Sewer Improvements, and what impact that it might have on the Hawkins Pond Project if Project 177 was determined not to be necessary and the fact that we have three new members on the Council, they deferred any decision until after they could meet with Staff at a workshop type session to discuss all the issues at hand so that everyone would be more familiar with these issues. At the workshop session which was held February 9, 1988, Staff presented a list of chronological events that took place back from 1971 until the present on this project. Briefly, they included a project in 1971 to construct improvements that would drain the area bordered by Diamond Path on the west, Dodd Boulevard on the south, the future Shannon Parkway on the east and 145th Street on the north and convey the storm water run-off from this area into the pond located on Mr. Hawkins property. One of the options of that plan was to construct a temporary holding pond in the Broback Industrial Park and continue with the remaining storm sewer, including removal of the temporary pond, at a later date. It appears that this is the only portion of the project that was ever done. Later, in 1981, when Orrin Thompson Homes proposed developing north of Hawkins Property, which would have required the extension of Shannon Parkway to provide additional access to Thompsons property, this project was brought up again. The project went as far as preparation of plans & specifications but was discontinued when the economy slowed down and Thompson decided not to go ahead with his project. This in turn meant that the construction of Shannon Parkway was not necessary and therefore the immediate need for Hawkins Pond was also unnecessary at that time. This brings us up to 1987 when Thompson Homes, now U.S. Homes, started up their development which required the construction of Shannon Parkway to provide better access to their development. This again triggered the need for obtaining and developing ponding area to incorporate the run-off from Shannon Parkway and the natural drainage basin surrounding the pond. In addition to the natural drainage areas, Staff looked at the areas included in 1971 plan and added the area south of Dodd Boulevard and north of County Road 42, because the new County Road 42 isolated this area when it was built in 1974, 3 years after this proposal. Page 2 Items for the March 1, 1988 Council Meeting These areas needed a permanent place to store storm water because the ponds they are using are temporary and the park areas are used as retention ponds which reduce the effectiveness of those areas as parks. The biggest question the Council has to deal with was the issue of benefit. It is not hard to show benefit to properties that directly drain into the area we're proposing to improve with the Hawkins Pond project, however it is more difficult to show benefit to properties that don't directly drain into Hawkins Pond. The City did an engineering report and subsequent feasibility study to propose a storm sewer system, very similar to the one proposed in 1971, that would convey storm water run-off, including the area known as "Twin Puddles", to the north into Hawkins Pond. This was done to insure that the city would be confident in projecting how storm water in this entire drainage area could be ponded. Although the engineering report shows it is feasible to construct a storm water collection system that would convey the water from "Twin Puddles" and the entire area south of 145th Street to the north, the construction of such a system is questionable at this time because the current system apparently meets the needs of the existing residents and is consistent with traditional storm water manufactures practices in the area. It is questionable if these needs will be met in the future because of several factors that do not currently exist in this area: 1. The current percolation rate appears to be satisfactory to handle the existing run-off, however with the use of additional fertilizers, pesticides, organic decay, etc. these may change the soil characteristics that would not allow an adequate infiltration rate to keep storm water ponding from being a problem. 2. The City will more than likely be faced with dealing with storm water run-off quality in the future and it would be much more manageable to deal with a fewer number of larger ponding areas than a larger number of smaller ponding areas. 3. The typical households in this area are empty nestors, therefore the demand for active park areas is not as great as it could be in the future when the empty nestors move out and are replaced by young families with young children. For these reasons, we feel that it is a relatively inexpensive insurance policy to construct the storm water retention pond, under Project 176, the Hawkins Pond Project, to include the entire district as the feasibility report proposes so that when future conditions demand draining storm water from the "Twin Puddles" area and the Broback Industrial Park area.there will be enough storage volume to accommodate this run-off. Then the only thing left to do in the future will be to construct the actual storm water collection system that will convey the storm water to the Hawkins area retention pond. Therefore, I would recommend that Council take action to approve the plans and specifications for City Contract 1988-2, Hawkins Pond Storm Water Improvements and authorize Advertisement for Bid Opening pending obtaining the necessary rights of entries or easements for this project.