805 Yankee Doodle Rd - Stormwater Mgmt Plan - Outlot A "INN JO 5060700010
Stormwater Management Plan for Ponds on Outlot A
Gertens will:
1. Ensure zero discharge of stormwater runoff(from a 1%/24-hour precipitation frequency storm
event (7.47")) from the yard waste composting operations and ponds on Outlot A to North Lake.
2. Dewater ponds on Outlot A to the newly constructed pond on Outlot I. The pond on Outlot I is a
zero-discharge pond, with up to 663,349 cubic feet of capacity prior to overflow. The volume of this
pond will be sufficient to accept the pumped water from the ponds on Outlot A. Timeline for
completion: August 2017
3. Remove residual soil and sediment deposition from the bottom of the ponds on Outlot A to restore
their original depths, after initial dewatering. The removed material will be reintroduced into the
compost operation. Timeline for completion: Mid-September 2017
4. Add stormwater volume storage capacity to the ponds on Outlot A to fully contain the runoff from
a 1%/24-hour precipitation frequency storm event (7.47")from the yard waste composting
operations on Outlot A and drainage contributions from Outlot H. This will be accomplished by
raising the outlet level 24 inches and raising grade at the north end of the ponds on Outlot A.
Timeline for completion: Mid-September 2017
5. Maintain stormwater volume capacity needed to fully contain the runoff from a 7.47" event from
the contributing drainage areas on Outlot A and Outlot H, by pumping out the ponds on Outlot A to
the pond on Outlot I as needed and/or used for irrigation on site, to ensure zero discharge to North
Lake. Notify City of Eagan Water Resources staff of any pumping operations and any discharge.
Timeline: Volume capacity management/maintenance will be continued until Gertens has removed
all soil and compost operations from Outlot A and the area has been restored to natural cover.
6. Minimize introduction of sediment into ponds on Outlot A by installing and maintaining filter berm
systems at pond inlet areas. Filter berms will be constructed of wood fiber mulch and rock and
modified as necessary for ensure proper function. Filter berms installed in May 2017.
7. Ensure unavoidable discharge(s)to North Lake from the ponds on Outlot A, due to Act(s) of God,
do not contain more than 0.050 mg/L of total phosphorus by treating the ponds and/or the
discharge(s)with aluminum sulfate, or employing a similarly effective phosphorus-reduction strategy,
and monitoring the quality of the discharged water, until Outlot A is vacated and restored to natural
cover. Notify City of Eagan Water Resources staff of any unavoidable discharge(s) and any
phosphorus-reduction plans.
8. Expedite the development of Outlot I. This will allow Gertens to vacate Outlot A,thus eliminating
phosphorus sources from Outlot A entering the ponds on Outlot A or North Lake. Expected to vacate
Outlot A by July 2018.
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