Hiawatha Golf Course. Minneapolis Park & Recreation Board City of Minneapolis. Update on investigations and Phase Two work plan 29 November 2016

Transcription

1 Hiawatha Golf Course Minneapolis Park & Recreation Board City of Minneapolis Update on investigations and Phase Two work plan 29 November 2016

2 Meeting purpose There are three primary goals for this meeting: o To briefly review findings from Phase One investigations o To describe Phase Two investigations o To update the public and neighbors on the status of related investigations and activities 1

3 Distinguishing inputs to the lake o o o East 43 rd Street pipe Minnehaha Creek Golf course ponds and pumps 2

4 Phase One primary issue The MPRB has been pumping stormwater and groundwater from ponds on the golf course to Lake Hiawatha since the 1960s In late 2015, the volume of water pumped from Hiawatha Golf Course was discovered to be far greater than allowed by a Groundwater Appropriation Permit issued by the Minnesota Department of Natural Resources in

5 Phase One investigations Understanding the amount of water pumped from the golf course required that we: o Gather existing groundwater data and develop a groundwater model o Develop a stormwater model to understand nongroundwater inflows to the ponds o Understand the interaction of groundwater and stormwater under a variety of high water and flooding scenarios 4

6 Phase One investigations: pumped water Measured pumped water using flow meters o Flow meters installed in two pumps in November 2015 o Allowed for the calculation of a reasonable estimate of volume of water pumped annually o Approximately 263 million gallons of groundwater pumped annually according to measurements and calculations o Current appropriations permit allows 36.5 million gallons of groundwater to be pumped 5

7 Phase One investigations: pumped water (100 gpm) groundwater (137 gpm) groundwater (70 gpm) groundwater (196 gpm) Net inflow to ponds o 40% of inflow is from Lake Hiawatha (lake seepage) o 60% of inflow is regional groundwater o 263 million gallons of groundwater pumped annually o 55 million gallons of stormwater pumped annually 6

8 Investigations: water quality Measuring quality of pumped water as a comparison to water in Lake Hiawatha o Water samples were collected from Lake Hiawatha, Pond E, and four monitoring wells in January 2016 o MPRB also used historic samples of water in Lake Hiawatha o Concentrations of phosphorus in samples of pond, ground and lake water were very similar o Total load of phosphorus from pumped water is less than 2.5% of the annual load of phosphorus to the lake o The impact of pumped water on the quality of water in Lake Hiawatha is negligible o Also analyzed groundwater and lake water for contaminants such as volatile organic carbons and diesel range organics and did not detect any contamination 7

9 Investigations: deep groundwater Assessing impacts on deep groundwater o An existing but rarely used deep well on the golf course was energized to pump deep groundwater for 72 hours beginning on 2/16/2016, during which time 1.7 million gallons of water were pumped from the well into Lake Hiawatha o During the pumping, data loggers in the monitoring wells were analyzed to determine if there was any drawdown in shallow groundwater o There was no recorded change in the groundwater elevations in the monitoring wells indicating there is no direct relationship between shallow groundwater and deep groundwater that is impacted by the current pumping 8

10 Investigation: water level recovery Measuring the impacts on pond elevations without pumping o A short term recovery test was performed from 12/31/2015 to 1/4/2016 o Pumps were turned off and water elevations in the pond were allowed to increase o Pond elevations increased 1 foot in 92 hours (from an elevation of to 809.8) o Pumps were turned on at the end of the test period o The test suggests, without pumping, the water elevation on the golf course property would equalize with Lake Hiawatha 9

11 Investigation: water level recovery Existing condition, pumps on drawing is not to scale elevations are approximate 10

12 Investigation: water level recovery Potential condition, pumps off drawing is not to scale elevations are approximate 11

13 Phase One findings If water levels were allowed to rise to under normal conditions with pumps turned off, based on the estimated basement floor elevations: o There are approximately 9 at-risk homes near the low spot at 19th Avenue and 44th Street o Based on a typical groundwater gradient, there may be an additional 9 homes at-risk in the watershed to the west of the golf course 12

14 Phase One findings If water levels were allowed to rise to under normal conditions with pumps turned off, based on the elevations across the golf course: o As most fairways are at an elevation of about 811 to 812, large areas of the golf course would be inundated o Because groundwater levels would likely be at or near the same elevation of the water on the golf course, a large area of soils outside of the inundated area would be saturated 13

15 17TH AVE S 18TH AVE S CEDAR AVE S LONGFELLOW AVE 19TH AVE S 20TH AVE S 21ST AVE S 22ND AVE S STANDISH AVE 23RD AVE S Phase One findings 24TH AVE S 25TH AVE S 26TH AVE S 43RD ST E 27TH AVE S 44TH ST E 44TH ST E 29TH AVE S 30TH AVE S 45TH ST E Lake Hiawatha 45TH ST E 46TH ST E 28TH AVE S 46TH ST E Legend 47TH ST E 47TH ST E Feet Feet Existing Open Water 27TH AVE S 29TH AVE S 30TH AVE S 14

16 Other Phase One activities o Meeting with owners of potentially impacted properties o Determining basement elevations of potentially impacted properties o Coordinating with regulatory agencies to understand the process of updating the groundwater appropriations permit and other applicable requirements. 15

17 Phase Two investigations Original project goals remain valid, with two significant modifications o Developing concepts to restore or reconfigure the golf course if pumping continues or to imagine other park configurations if pumping stops o Improving the ecology of the creek through the golf course property o Considering options for the pipe from East 43 rd Street (north side) that empties into Lake Hiawatha o Understanding fully the potential groundwater impacts on nearby private properties if pumping stops 16

18 Phase Two investigations and explorations Work will proceed in concert with City of Minneapolis Department of Public Works (DPW) As appropriate, MPRB and DPW will engage other agencies and regulators to review findings and directions We need to understand impacts beyond the areas considered in Phase One (the golf course and nearby private properties) 17

19 Groundwater appropriations permit City and MPRB staff met with MnDNR staff in November o Reviewed general outcomes of Phase One investigations o Described activities anticipated for Phase Two o Asked for comments on a work plan o Reviewed the status of the permit 18

20 Phase Two primary issues Framing regulatory parameters for pumping options Determining specific effects of pumping scenarios on the golf course and nearby private properties Understanding effects on water quality, ecology, and public infrastructure Defining a preferred scenario on a reasonable timeline 19

21 Phase Two investigations and explorations Four major tasks are envisioned as a part of Phase Two o Engaging internal and external resources to accomplish Phase Two o Updating elected officials, regulatory agencies, and the public at the outset of Phase Two o Conducting further investigations focused on the implications of pumping and no pumping scenarios o Exploring options focused on o Continued pumping o Reduced pumping o No pumping 20

22 Phase Two investigations and explorations Options will consider factors including: o Defining pumping volumes and review of permit allowances o Impacts on golf operations and golf play o Water quality impacts on Lake Hiawatha and Minnehaha Creek, and as appropriate on Lake Nokomis o Short- and long-term ecologic impacts o Impacts on nearby private properties o Public infrastructure impacts o Likelihood of achieving regulatory approvals Exploration of options will result in the identification of a preferred scenario 21

23 Phase Two schedule and outcomes TASK 1 Engage internal and external resources TASK 2 Update officials, regulators, public TASK 3 Conduct further investigations TASK 4 Explore pumping options SCHEDULE o Consultants engaged by December 2016 o Public meeting on 29 November 2016 o Updates complete by December 2016 o Investigations completed by March 2017 o Preferred scenario identified by July 2017 OUTCOMES o Day-to-day project management process defined o Consultants engaged o Updates completed o Status review with MnDNR completed o Baseline investigations supporting options accomplished o Regulatory concerns identified o Options framed for each scenario o Review of options accomplished o Preferred direction identified 22

24 Questions 23