The overall design goal for the LID subdivision was to use a cluster layout to reduce overall site imperviousness and preserve open space. In addition, stormwater infiltration was used wherever possible to preserve the predevelopment hydrologic function of the site.
The LID subdivision design was based on a Paired Watershed Approach: One watershed served as a control while the other was called a treatment watershed. The use of a control allows for statistical correction for year to year variations in weather. Click on the boxes to the right for more information on the Paired Watershed Approach.
Paired Watershed Study Design Fact Sheet
1993. Written by Dr. John C. Clausen and Dr. Jean Spooner, North Carolina State University, and reviewed by Steve Dressing, U.S. EPA.
The purpose of this fact sheet is to describe the paired watershed approach for conducting nonpoint source (NPS) water quality studies. The fact sheet describes the statistics used.
Automated Introduction to the Paired Watershed Approach for Jordan Cove
(6:39 minutes. 2006. By Dr. Michael Dietz.)
This is a narrated video presentation designed to describe the paired watershed approach, and can be paused and started as desired.
The control watershed was an existing 14-acre residential watershed containing 43 lots built in the same general vicinity of the treatment watersheds in 1988. Stormwater runoff was monitored at the outflow of a stormwater pipe at the watershed outlet. This watershed allowed for researchers to factor out weather differences from year to year, when comparing data between the treatment and control subdivisions.
The traditional watershed was five acres in size and contains 17 residential lots. This watershed was developed using standard zoning and construction practices. It is accessed by a 24 foot wide asphalt road with typical curb and gutter stormwater conveyance system.
The four acre LID watershed now contains 12 lots. A host of LID practices/BMPs were used. A cluster approach was used to aggregate homes closer together, leaving more open space in the watershed. Shared driveway entrances reduced imperviousness. Lawn sizes were reduced and low-mow and no-mow areas were designated to reduce fertilizer and maintenance impacts. The access road is narrower (20 ft.) than typically allowed by ordinance and was constructed of interlocking concrete pavers that allow infiltration. Rain gardens were installed in each lot and a bioretention area in the cul-de-sac was installed.
Best Management Practices (BMPs) Used
Rain gardens were installed in each lot to catch roof runoff. For more information on rain gardens, check out our Rain Gardens Page.
A bioretention area was made in the middle of the cul-de-sac in order to collect stormwater runoff.
No curbs were installed, allowing for any stormwater runoff that did not sink in to the pervious road to be directed into the grass swale on the sids of the road. The swales helped to maintain the predevelopment hydrology of the site, which is the goal of low impact development.
Pervious pavement was installed for the road. Uni-Ecostone® blocks were installed over a base designed for infiltration, with the spaces between the blocks (about 12%) filled with a pea stone gravel.
Several of the shared driveways were constructed with pervious alternatives to asphalt. Two were constructed with white crushed stone, two were constructed with Uni-Ecostone®, and two were constructed with traditional asphalt.
Low / No Mow Zone
The original design specified low-mow and no-mow areas on each lot. However, homeowners chose not to adopt this portion of the design, and most of each lot was maintained as lawn.
The grasses of the “Jordan Cove Mix” were fescues, which are tolerant of the local condition and have low fertilizer and water requirements. The custom mixture was composed of:
- 30% perennial ryegrass
- 20% Kentucky bluegrass
- 50% chewings fescue/hard fescue
Professors from UConn’s College of Agriculture and Natural Resources, along with graduate students, provided short workshops and one-on-one education for residents of the low impact development subdivision
A cluster layout was used instead of traditional lot layout. The purpose of the cluster layout is to minimize the extent of the developed area, so that a larger portion of the property can be kept in open space.