Techniques

BOB Sites
There are three watershed site areas involved in the BOB project:

• Mid Cumberland (Urban) / Multifamily: in the Germantown neighborhood of downtown Nashville, just a few short blocks away from the Cumberland River. 
• Mid Cumberland (Urban) / Single Family: in the Antioch area of Metropolitan Nashville in the Mill Creek Watershed.
• Harpeth River Watershed (Suburban) in Franklin, TN.
• Red River Watershed (Rural) in Logan County, Kentucky.

The work in each of these three site areas is carried out in partnership with the landowners, developers and builders along with the wide array of expert guidance on the BOB Committee, including engineers, architects, landscape designers, builders, environmental scientists, biologists, hydrologists, and local watershed protection groups.

Better Site Design
One of the best ways to protect water quality is to manage stormwater runoff for maximum infiltration and recharge through the ground instead of rapid runoff through the storm sewer system. There are a number of simple, inexpensive, and practical ways to do this through better site design and landscape features.

For example, one of the most important predictors of water quality impact from a new development site is the total percentage of impervious surface or hardscape cover on the finished site. The less you have in hard surfaces, such as roofs, roads, driveways, and sidewalks, the less damage the rainfall runoff will do to receiving streams. That’s because more of the rainfall has a chance to slow down and infiltrate into the ground, thereby filtering impurities and avoiding flash flooding that scours stream banks and carries heavy loads of pollutants downstream.

Better site design features can reduce the total impervious cover and prevent water pollution. With input from the Center for Watershed Protection and through coordination with the developers and builders, BOB residential housing sites will incorporate a number of these water protective features including:

• reduced width of streets and sidewalks,
• open channel roads instead of curb and gutter
• shared or dual track driveways
• use of pervious concrete or pervious pavers
• vegetated islands in the center of cul-de-sacs
• loop roads instead of cul-de-sacs
• minimizing the footprint of the houses and roofs
• diversion of rainfall from roofs into rain gardens and vegetated swales
• use of rain barrels to collect roof runoff and irrigate lawns and gardens

These practices serve to slow and filter stormwater runoff just reducing the volume and pollutant load of rainfall events.

Earth Craft House Program
The project demonstration sites will also incorporate the high performance home construction practices as exemplified by the Earth Craft House program. This program calls for a higher level of excellence in home construction quality that incorporates maximum energy efficiency and water conservation technology.

The construction techniques of the program result in much lower utility bills, healthier indoor air quality, and a longer lasting, more durable home. The Earth Craft House program uses a systems approach to the house so that cost savings in one area offset any additional costs in other areas. As a result, Earth Craft certified homes cost no more than 3-5% more than any conventional home construction. Yet the sells for a premium on the housing market.

To date over 1500 Earth Craft Homes have been built and certified in the Southeast since the program began just a few years ago. The techniques and cost effectiveness are well demonstrated and Tennessee homebuilders are already showing interest in this program, especially in view of its attractiveness to homebuyers.

The BOB project hopes to make possible the first Earth Craft certified homes in Tennessee. These high performance homes will offer opportunities for builders and home buyers to learn about these features and incorporate them into their housing and business decisions.