Consider Stormwater Improvements at Rum River Hills Golf Course - A Continuation of Discussion Related to 2011 Flooding Concerns

Last summer the City experienced several significant rainfall events that lead to many localized flooding concerns, and resident complaints. The large volumes of precipitation that occurred over a short period of time appears to have elevated the groundwater within areas of the City, and prohibited the generous rate of infiltration that typically takes place in the Anoka sandplain. Throughout the 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.

At that meeting the Committee briefly discussed the areas of concern, and directed staff to prepare plans and specifications for the items identified in category 3. Once this direction was ratified by the City Council on September 13, 2011, and the plans completed, it was too late in the season to secure bids and complete the improvements in 2011. It was then decided to delay construction until 2012, where some of the improvements could be completed by inclusion in the street maintenance program. Staff is in the process of finalizing plans for these items and intends to solicit quotes for the improvements this spring/summer. Depending on the direction staff receives for potential improvements to alleviate some of the outstanding concerns identified over the next couple of months, additional plans can be incorporated into one plan set for bidding.

The Golf Course representatives have been notified of the meeting and have recieved a copy of the agenda.

Staff prepared a brief RFP in the fall of 2011, to investigate the areas of concern, and distributed it to members of the City's consultant pool in the fall of 2011. The goal of this project was to have an independent third party evaluate the areas, provide options for corrective actions, and associated estimates to implement the work. Hakanson Anderson was awarded the project to undertake these investigations, and they have since completed their analysis and compiled a report that references potential solutions for each area identified. Attached to this case is an excerpt of the final report.  This item was introduced in general terms at the February Public Works Committee meeting, with the direction being that staff would come back before the committee over the next several months to discuss the merits of each potential improvement in more detail. This case will focus on section three of the report - Rum River Hills Golf Club.


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 are summarized as follows:

Hole #1  (Area 1)
There is a large pond located adjacent to Hole #1, which has a 12" plastic pipe that serves as the outlet.  This outlet pipe was televised after the flooding was brought to the attention of the City last year, and the video revealed that there were several sags in the line, and many joints have been compromised with root intrusion.  This pond was evaluated with the City storm water model, and it was determined that the 12" pipe was the limiting factor and slightly undersized to accommodate the flows.  Up-sizing this line to an 18" pipe, and installing a manhole at the outfall would improve the efficiency of the stormwater routing.  It should be noted that the City has always worked with the golf course on the outlet to this pond and previously installed a removable weir so they could control the flow leaving the pond with a removable weir.  We are proposing to maintain this pond elevation adjustment for the golf course by installing a new manhole structure with a similar feature, as they currently utilize this pond as a course amenity and irrigation supply.  The golf course likes to retain as much water as possible in the pond, installing the removable weir will provide the flexibility to retain small storm events and store the water while allowing larger events to pass through the system quickly.

Cart path area near the club house (Area 2A, B)
There is a pond north of the club house which is connected to the pond on hole #1.  There are several cart paths around this smaller pond which experience localized flooding on occasion.  By up sizing the existing undersized culvert connections we can allow more water to pass through the system quicker.  The elevations on certain areas of the paths are below the maximum elevation of the pond.  The paths would need to be raised if the intent is to not have water on the paths during the larger storm events, but doing so would have ramifications on other areas of the site upstream.

Saturated soil along Hole #15 (Area 3)
Hole #15 is along the Rum River, and there is a rock dam across the main drainage way from the golf course down to the river.  This dam creates a ponding area adjacent to the fairway, and the water elevation of this pool is very close to the fairway grades, resulting in saturated soils in the area.  The golf course excavated an area adjacent to the fairway last fall in an effort to determine the source of the water and dry the area up.  Several draintile lines were uncovered by the excavation and they appeared to be plugged and collapsed in several locations.

Staff visited the site May 10th and observed the conditions in this area.  The golf course has excavated a low area and swale on the edge of the 15th fairway.  Golf course representatives said the low area had open water in it that flowed through the swale all winter, but the ponding area behind the dam froze over.  This excavated low area has standing water that flows through the swale to the river.  The water level behind the dam is approximately 1 foot below the adjacent fairway grades.

The recommendations for this area are two-fold; the golf course will undertake work that is outside of the drainage and utility easement (regrading and/or draintile installation), and the City will provide improvements within the drainage and utility easement.  The golf course will monitor the low area this summer and are thinking about improving it into another water feature on the course.

They will also contact a draintile company to evaluate the installation of a new system along the fairway.  They are also interested in removing sediment from behind the dam so that they can re-install a floating fountain.  Staff will assist by researching state requirements for disposal of pond dredge material.

The City will evaluate options for changing the control structure on the rock dam.  Currently there is an open top metal channel approximately 2 feet wide, which directs water over the top of the dam.  Rocks are placed against the edges of the channel and as the depth increases water flows over the rocks.  There is a metal dam approximately 70 yards upstream which has a flow width of 4 feet.  The control structure on the dam should be widened to match the upstream structure, and the elevation of the top may be lowered.

Hole #3 and #17 (Area 4 A, B, C)
The fairways of Hole #3 and #17 also experienced flooding last summer.  These areas receive stormwater runoff from an area north of the golf course.  The water passes through several ponds connected by culverts, which form a water hazard on the course.  The pipes have shifted over the years, and there are several locations where the upstream invert is lower than the downstream invert, thereby decreasing the capacity of the pipe and holding back flow.  The golf course is also interested in dredging a pond in this location.  The idea in this location is to replace the pipes with slightly larger pipes to increase flow, and re-establish the proper invert elevations.  This work will require coordination with the golf course so that alternate routes around the work areas can be set up before construction begins.

The funding source for these improvements is the Storm Water Utility Fund.  The opinion of probable construction costs, as prepared by Hakanson Anderson, are estimated at $47,000, with a breakdown as follows:
Area 1 $ 30,000
Area 2 $ 7,000
Area 3 $ 5,000
Area 4 $ 5,000
Total $ 47,000

Staff recommends authorizing preparation of plans and specifications for these various improvements, and requests authority to advertise for bids.  Depending on current staff workload, this project may have to be consulted out to our engineering pool for completion this year to avoid future flooding concerns on the golf course.

Motion to recommend to the City Council that staff be authorized to prepare plans and specifications for these various improvements, and authorization to advertise for bids.