Grande Park Subdivision Detention As-7 Dam Reservoir Report

Last Updated: December 5, 2025

Located in Plainfield, Illinois, the Grande Park Subdivision Detention As-7 Dam serves as a vital structure for flood risk reduction in the area.


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Summary

Constructed in 2004 by COWHEY GUDMUNDSON LEDER, LTD., this earth dam stands at a height of 7.8 feet and spans a length of 750 feet. With a storage capacity of 114 acre-feet and a drainage area of 1.32 square miles, this dam plays a crucial role in managing water flow and mitigating potential flooding events along the EAST TRIB EAST BR AUX SABLE CR watershed.

The dam features an uncontrolled spillway type with a width of 197 feet, allowing for the release of excess water during high flow conditions. While the hazard potential is classified as low, the risk assessment indicates a moderate level of risk (3). The dam is inspected every five years, with the last inspection conducted in July 2019. Despite the absence of a condition assessment, the Grande Park Subdivision Detention As-7 Dam remains a key infrastructure for flood control in Kendall County, Illinois, ensuring the safety and protection of residents in the region.

As a privately owned structure regulated by the Illinois Department of Natural Resources (IDNR), the Grande Park Subdivision Detention As-7 Dam exemplifies the collaboration between private entities and state agencies in managing water resources and enhancing climate resilience. With its strategic location and design features, this dam not only reduces flood risks but also contributes to the overall water management efforts in the area. As climate change continues to impact water systems, structures like the Grande Park Subdivision Detention As-7 Dam play a crucial role in safeguarding communities and promoting sustainable water resource practices in Illinois.

Year Completed

2004

Dam Length

750

Dam Height

7.8

River Or Stream

EAST TRIB EAST BR AUX SABLE CR

Primary Dam Type

Earth

Surface Area

8.5

Drainage Area

1.32

Nid Storage

114

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Soil

Nid Height

8
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.