 |
PLANNING AND ZONING
New Type of Residential Development Unveiled
at Conservation Subdivision Design Workshop
 On August 27th and 28th, the City of O’Fallon held a Conservation Subdivision Design Workshop for approximately 50
O’Fallon public officials, local developers and engineers with the goal of educating participants about a new type of residential development.
Conservation subdivisions differ from conventional subdivisions in several ways. They work with the natural environment by minimizing the amount of grading against the natural topography, establishing a more natural pattern of storm water management, and preserving much more open space. This is typically achieved by platting smaller lots and leaving a large percentage, often 50% of the property, in common open space. Conservation subdivisions also employ
low-impact development techniques, such as rain gardens, permeable pavement and vegetated bioswales. Another key feature of conservation subdivisions is the emphasis on restoring native ecosystems. In O’Fallon, common native ecosystems would be woodland savannas and prairies. These subdivisions often restore these native ecosystems through large-scale projects in the common open space, and even in some cases through small-scale projects such as native plantings on individual lots.
There are also economic benefits in using conservation development techniques for new residential developments. In fact, conservation subdivisions have been shown to often yield higher-priced lots and homes even though lots are typically smaller than conventional developments. Experience has shown that many people are willing to pay more to live in a neighborhood that has natural and open space amenities. Also, the infrastructure necessary to create a subdivision, including roadways and storm sewer pipes, can be reduced by re-orienting street networks to run with the natural topography of the land and by employing alternative storm water management techniques.
 The City hired consultants from Applied Ecological Services, Inc. (AES) to run the two-day workshop. In addition to educating
participants about the benefits and challenges of conservation subdivision design, AES ran a design charette on a local test property, the Ahl property on the northeast corner of Milburn School Road and Old Collinsville Road. This property was previously approved for a conventional, 202-lot residential subdivision, which has not been built. Workshop participants broke into teams and spent a couple of hours designing an alternative layout for the Ahl property which included several of the features they learned about earlier in the day. After everyone shared their designs, AES presented a cost-comparison between the conventional subdivision and the conservation subdivision. Overall, the conservation subdivision design yielded four more lots (although smaller ones), conserved over 50% of the subdivision in open space, and saved $665,000 in infrastructure and development costs.
While conservation subdivisions may provide for greater open space, alternate storm water management techniques, preservation of natural areas, and reduced infrastructure costs, there are also challenges that will need to be addressed, such as variances to existing city requirements, smaller lots, and the private sector determining whether there is a market in this area for these types of subdivisions. This workshop was the beginning of the educational
process for the community to evaluate whether this concept is right for O’Fallon, and if so, how to make it work as an option for future developments.
If you are interested in seeing the results of the charette, and finding out more about conservation subdivision design, you may go to the City’s web site at www.ofallon.org.
Native Planting Example Rain Garden Example
| |
