CLIENT

Village of Grayslake

LOCATION

Grayslake, Illinois

COSTS (2016-2022)

$30,000

PROJECT FEATURES

Drainage Study
Stormwater Mitigation

SCOPE OF SERVICES

Stormwater Modeling
As-built Review
Agency Coordination
Permit Assistance

During and after the 2017 storm events in Lake County, standing water throughout the Village was generally limited to detention basins, floodplains, and known problem areas. However, high water levels within the Haryan Farm subdivision and West Trail subdivision ponds persisted for an extended period, which had not occurred following previous large storm events. Since this system outlets to an existing 18” field tile line located on private property outside of platted easements, the Village requested GHA investigate the existing outlet capacity and explore alternatives to relying on this existing field tile line.

Gewalt Hamilton Associates (GHA) reviewed as-built subdivision records, interacted with Village staff, and created existing and proposed stormwater models for the areas upstream and downstream of Haryan Farm Subdivision. The objectives of this effort were to:

  • Quantify the volume and rate of stormwater flow tributary to the Haryan Farm Ponds and the downstream outlet pipe during design storm events and compare with drainage conditions experienced during and after the July 2017 storm event.
  • Identify and evaluate existing stormwater infrastructure between the Haryan Farm North Pond and the Lake Street box culvert.
  • Determine appropriate storm sewer sizing and suggested routing to improve the Haryan Farm North Pond outlet condition without unduly affecting downstream properties.

    • The alternatives analysis provided the Village with a summary of existing and proposed water surface elevations associated with a suite of proposed storm sewer improvement options. GHA provided recommendations for improvements that would result in a cost-efficient solution to lower upstream water surface elevations without adversely impacting downstream properties. The proposed improvements have been budgeted for in the upcoming Capital Improvements Plan.