Receive plans and specifications and authorization to bid City Project #12-28 Rum River Hills Storm Sewer Improvements

The City experienced several significant rainfall events in 2011 lead to many localized flooding concerns and resident complaints.  Throughout that summer and fall staff worked hard at registering and
responding to the calls, and evaluating the situations on an individual basis to determine whether quick fixes could
be implemented (culvert obstructions, re-ditching, etc.) to alleviate the immediate concerns.

This item was discussed at the Public Works Committee on August 15, 2011, and at that time staff summarized the
areas of concern that were being investigated based upon citizen complaints received. The attached summary was
presented at the meeting; which outlines the concern identified, actions steps to evaluate the concern, additional
investigations that would be necessary to fully understand the situation, and recommendations for specific projects
that could be implemented rather quickly and inexpensively. At that time we classified the issues into 3 categories:

1. Those that required no further action. They were evaluated and corrected, or did not need correcting because
the water was fully contained within a dedicated drainage & utility easement (functioning as designed).

2. Those that required additional investigation and evaluation before deciding on a long term solution, and
implementing corrective actions.

3. Those that had an identified recommendation for immediate action.

Throughout the winter areas in the second category were investigated, evaluated and brought forward for approval of plans for corrective actions. 

The stormsewer modifications at Rum River Hills Golf Course are the latest improvement to be reviewed by the Public Works Committee.

The Golf Course representatives will be notified that the project is being considered for advertisement for bids.

Rum River Hills Golf Club is located east of Trunk Highway 47 at 167th Avenue NW. Several areas were
evaluated and summarized in the report. The golf course was platted in the early 1980's, and at that time linear
drainage and utility easements were secured on the site to encumber areas where off-site stormwater was routed
through the site. Many areas of the site experienced flooding concerns last summer, and they were summarized
at the May 15, 2012 Public Works Committee Meeting. A motion was made to recommend preparation of plans and specifications for storm drainage improvements at Rum River Hills Golf course. Hakanson Anderson has prepared the plans and specifications and their design will be presented tonight.

Four areas were identified as need improvement, each will be discussed in detail along with the proposed improvements.

Area 1 (Pond adjacent to Hole #1)

There is a large pond along the west side of hole #1. This pond receives runoff from the area west of TH 47 and discharges through a 12" pipe. This pipe was televised in 2011 and has sags and root intrusions. Stormwater modeling indicates this pipe is undersized for the drainage area. The existing pipe runs through an area between fairways then passes under a tee box and adjacent to and traps and a green before discharging to a ditch. The existing pipe is fairly close to the property line and there are several trees that provide screening for the adjacent properties that would need to be removed. Replacement of the pipe on its current alignment would require extensive restoration and temporary relocation of the tee box. An alternative alignment was selected which will cross the fairway instead of the green and avoid the tee box. This relocation will allow for construction of a surge pond at the downstream end of the pipe which will minimize erosion. This pond will be incorporated as a water feature on the course. The main pond serves as an extended supply for the course irrigation system. An outlet control structure with a removable weir will be installed to allow regulation of the water level in the pond. The realignment will require removal of several large trees. The existing drainage and utility easement will need to be revised to cover the new pipe.

The new outlet pipe will be increased to 18" from the current 12" size. Modeling of the existing system indicates the pond would be above normal water level for almost 4 days for the 100 year event, after installation of the new pipe the pond will be above normal water level for just over 2 days.

Area 2 (Ponds North and West of the Club House)

There are ponds northwest and north of the clubhouse. The northwest pond is connected to the north pond by a culvert under the cart path. The cart path is subject to flooding after a 2 inch rain event. The pipe will be replaced with 3 parallel pipes. The cart path will still be subject to flooding after a 4 inch rain event The design process evaluated raising the elevation of the path; however, this could cause water to overflow the pond bank towards the clubhouse. The 2 inch rain event has a probability of once every 5 years, the 4 inch rain has a 10 year probability. Golf course representatives were contacted during the design process and they felt over topping the path during an event larger than the 10 year event would be acceptable.

The culvert under the path at the east end of the north pond will be replaced with twin pipes to provide better capacity and reduce the chance of over topping the path.


Area 3 (Area around Holes #15 and #16)

There is an existing metal weir across the ditch which provides drainage for the course. The ditch upstream of the weir has silted in and in some places is overgrown with vegetation. The plans propose lowering the weir by 6 inches, removing the decorative rock lining the ditch, lowering the grade of the ditch and replacing the rock.

The golf course will performing work work in area 3 to install draintile to address the the saturated soils on the fairway. They will also be stabilizing the pond dug during the summer of 2011. This pond was excavated to provide a drainage way for the saturated soils adjacent to the fairway.

Area 4 (Area around Holes #3 and #17)

This area receives drainage from an area north of the golf course. There are a series ponds connected by culverts that are in poor condition that will be replaced. Several of the culverts have shifted to the point where the downstream end is higher than the upstream end, which restricts flow. The connecting ditches will be cleaned and regraded as part of the project.

This project was reviewed by the Public Works Committee at the September 18, 2012 meeting.  The motion was made to approve moving forward with the project and to bring the plans and specifications to the September 25 meeting for approval of the plans and specifications and authorization to advertise for bids.

The Committee requested that notification be provided to residents within 700 feet of the project.  This notification will be sent out during the period when the bids are advertised.

The engineers estimate for this work is $105,000.

Staff recommends approval from the City Council to advertise the project for bids.  The bids will be opened and brought back for authorization to award a contract.

The funding for this project will come from the Stormwater Utility Fund.

Motion to receive plans and specifications for IP 12-28 Rum River Hills Storm Sewer Improvements and authorize advertisement for bids.