Mt. St. Joseph in Lake County
Mt. St. Joseph is a health care facility in Lake County, Illinois, located near Lake Zurich, just north of IL Rt. 22 on IL Route 12. W-T Civil Engineering was hired by Harold R. Lutz & Associates to provide civil engineering services for a new 19,000 square foot office building. This included several new driveways, pathways and ponds. The project required zoning and extensive permitting with Lake County, the Illinois Environmental Protection Agency, and the Illinois Department of Transportation.
One challenging aspect of the storm water management design for the project was the determination of the existing on site floodplain elevation. Based on current floodplain maps (issued by Lake County), an existing pond on site was considered Zone A Floodplain. This is a floodplain that experiences flooding during heavy rain events, however, an exact 100-year storm elevation is not known. W-T Civil Engineering determined the existing tributary area to the pond. We then created a new storm water model of the existing conditions. We were then able to determine how deep the existing pond could become during the 100-year storm.
Several site-engineering challenges created unique civil design opportunities. These distinctive civil design attributes included:
* Storm Water Detention Modeling for Lake County
* Sedimentation Ponds to promote reduction in particulate leaving the site
* Handicap Access to all proposed site features (ADA Accessibility)
* Wet Bottom Pond for Storm Water Pollution Prevention
* Compensatory storage mitigation
* Zone A Base Flood Elevation Determination
Mt. St. Joseph
Best Management Practices
The latest popular acronym in Site Engineering Design is Best Management Practice (BMP).
A best management practice is defined as a structural or non-structural method intended to reduce pollution from entering ground water and surface water. In recent years BMPs in the Chicago Metropolitan Area often refer to temporary soil erosion control measures, such as silt fences and storm water inlet protection. These are intended to reduce pollutants into bodies of water during construction. Today in counties such as DuPage County, and soon Cook County, BMPs refer to absolute storm water pollution prevention improvements. These are required to be maintained by the owner for the life of the site. These new BMPs are intended to reduce storm water pollutants such as nutrients, pesticides, etc over the life span of the storm water management facility. Some of the more popular BMPs already bein utilized in DuPage County include rain gardens, vegetated swales, permeable pavers, manufactured products, and several others. Below is a short description of some options for BMPs.
Rain Garden
A rain garden is a depressional area (detention/retention pond) designed to retain water and cause infiltration through soil media to help reduce pollutants from entering the storm sewer system. Often rain gardens can be designed to beautify a site by using native plants, which not only increase the splendor of the area they are located within, but also increase the ground water infiltration.
Established Rain Garden
Manufactured BMPs
Manufactured BMPs include storm water quality inserts or structures which become an integral part of the underground storm sewer system. These manufactured BMPs can provide site engineers with scientific testing for pollutant removal, which often expedites the permitting process. However, often manufactured BMPs are expensive, and they require frequent maintenance.
Dry Wells
A drywell is an underground storm structure (like a catch basin or manhole) which has holes cored within it. This allows for ground water infiltration of storm water runoff. Drywells are also used in areas where existing storm sewer systems do not exist. Dry wells are an effective BMP, however, in the Chicagoland area dry wells are often not a viable option, because dry wells require deposits of sandy soils.