Tuesday, January 16, 2018

District proceeds with plans to optimize drainage near Grass Lake and Snail Lake

Winter weather means construction season in the watershed world, and we are moving forward with plans to optimize drainage and restore natural habitat in the Grass Lake and Snail Lake area. This work is part of an ongoing study commissioned by the District in response to persistent high water conditions and concerns among local residents.


This map shows the location of projects underway to restore habitat and optimize drainage of the Grass Lake and Snail Lake system, along with surface water flow paths shown by the blue arrows. Numbered items are explained in the “Projects underway” section below.


Projects underway


1) Restore natural habitat


In partnership with Ramsey County, we were recently awarded a Conservation Partners Legacy Grant of $252,000 from the Minnesota DNR to restore 60 acres of degraded forest and about four acres of wetland habitat. This 4-year project will begin this year as we remove invasive vegetation like buckthorn and prepare the site for native planting.

2) Grass Lake berm

Plans are underway to construct a permanent berm along the north side of Grass Lake to replace two sections of temporary sandbags. The berm will help contain high waters on the lake’s northern shoreline, and construction is slated to be complete by March.


3) Twin Culverts under Ramsey County trail

East of the berm, we plan to add two 44-inch by 26-inch culverts to carry water from Grass Lake underneath the Ramsey County walking trail to an adjacent marsh. This will improve drainage beyond the smaller 18-inch culvert currently running underneath the trail.


4) Dredge Grass Lake east shoreline


We will remove about 775 cubic yards of sediment along east shoreline of Grass Lake and dig out a 360-foot-long channel 2 feet below the lake bottom to allow better drainage to the new culverts being installed.


5) Improve channel between Grass Lake and Railroad Tracks

To improve flow between Grass Lake and a wetland area near the railroad tracks to the east, we will remove about 1,825 cubic yards of sediment and dig out a 560-foot-long channel.


6) Improve channel into West Vadnais Lake

To improve flow from Grass Lake into West Vadnais Lake, we will remove about 160 cubic yards of sediment from the downstream end of two Rice Street culverts. Riprap will be placed at the end of the culverts to keep sediment from building up in the future.


7) Replace West Vadnais Blvd. culvert


To keep water flowing south under West Vadnais Boulevard, we will replace the current 12-inch culvert with a larger and slightly lower 44-inch by 26-inch culvert.


8) Improve West Vadnais Lake outlet

We are pursuing permits to improve the West Vadnais Lake outlet, which flows south under I-694, by replacing a section of the current 15-inch pipe with a larger 24-inch pipe. In addition, a new trash guard and riprap will help keep debris from blocking the outlet.


Potential projects

We are studying the feasibility of several potential projects to create additional water storage within the Grass/Snail Lake system or move water out of the system. These options are outlined in a recent Barr Engineering study and include:
  • Installing an outlet pipe from Snail Lake, which is currently landlocked, to Grass Lake. The pipe would be equipped with a manual gate to prevent backflow into Snail Lake, and only opened when Grass Lake water levels are low enough to accept flows from Snail.
  • Pumping water from Snail Lake to Sucker Lake in order to lower water levels in Snail Lake. An augmentation pipe is currently in place to carry water from Sucker to Snail (when Snail Lake levels are low), but it was not designed to work in reverse.
  • Study the connection between Snail Lake and the marsh bordering it to the northwest to confirm its connection to Snail Lake and its availability to store Snail Lake flood waters.
  • Managing water levels in ponds around Gramsie Road.
  • Constructing an emergency overflow on Grass Lake that would carry water north in very large storm events, reducing the risk of Rice Street flooding.
  • Lowering the outlet for West Vadnais Lake to create additional water storage in both West Vadnais and Grass lakes.
  • Installing a system to pump and treat water from West Vadnais into East Vadnais Lake in order to promote drainage of the entire Grass/Snail lake system. Since St. Paul draws its drinking water from East Vadnais Lake, any water pumped there would need to meet strict quality standards according to St. Paul Regional Water Services and other regulators.

5 comments:

  1. Appears to be just another expensive project to protect structures/infrastructure which were built where they never should have been. Just our watershed district's mini Houston, or your choice of names of many other locations suffering high water levels due to the effects of storms that have become the new order of the day. Those affected should thank their lucky stars that the district is able to assess taxes on all members for projects without the necessity of having to go through open meeting truth in taxation meetings.

    It would be helpful if an overlay to the provided map could be provided to show the direction of flow of surface water in the area.

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  2. In 2013, our District expanded its boundaries to include land previously managed by the former Grass Lake Water Management Organization. Since then, we’ve worked to gain a better understanding of drainage issues and flood risk around Grass Lake and Snail Lake. While homes in this area have not experienced significant flooding, it is important we take steps to optimize drainage and proactively plan for increased rain events that are becoming more frequent in Minnesota. As with all District projects, our Board of Managers will continue to closely weigh the cost and benefits of planned projects in this area.

    As for the flow direction, thanks for your suggestion. We have added arrows to show the flow of water pertaining to this post, and if you’d like to view additional drainage flow paths, please visit our new interactive map at: http://arcg.is/01ijiH

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  3. The completion date for the various steps is missing except for steps 1 and 2. Are steps 2 through 8 expected to be completed by March 2018?

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    Replies
    1. Items 3, 4 and 5 should be completed by the end of February. We're still developing project schedules for items 6, 7 and 8, but shooting for approximately May 1 on those.

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  4. Many residents have worked very hard to bring about these measures. The drainage system needs to be addressed as too much water was routed into Grass Lake. Thank you to the Watershed District and the residents for working to help protect our homes and parks.

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