Rating System

LEED BD+C: New Construction, LEED BD+C: Core and Shell, LEED BD+C: Schools

Rating System Version

v3 - LEED 2009, v2 - Schools 2007, v2 - LEED 2.2, v2 - LEED 2.0

Inquiry

Site Conditions - The site consists of 4.74 acres located on the north side of Ballenger Creek Drive and south of interstate 70. The majority of the site has been graded to be relatively flat with slopes of approximately 3% to 4%. Along the sites eastern boundary a large swale conveys drainage to a 4\' x 12\' concrete box culvert under Ballenger Creek Drive. The constructed portion of the site has approximately 24,000 sq. ft of paving for a parking lot. A pre-existing storm sewer system runs through the site and conveys drainage from the adjacent commercial site to the west through the site to the existing storm drain system in Ballenger Creek Drive. The site drainage from this area and the site is conveyed to a regional Stormwater management pond. The pond was designed in accordance with the MD 2000 Stormwater Management Regulations and follows the guidelines of the Maryland Stormwater Design Manual. The manual was used as a standard by USGBC when developing the requirements and guidelines for the credit. The pond was approved by the City of Frederick in 1998. This pond was designed to handle hundreds of acres in the region. Our Request - We are asking for clarification on whether or not our off-site pond and our approach qualify the project for the credit. Under the regulations in effect at that time, the 2 year, 10 year and 100 year storms were controlled for quantity within the pond. Extended detention of the 1 year storm was used in the pond for quality. All design storms are 24 hour storms. The 1 year extended detention meets the current MD 2000 Regulations for Channel Protection volume (Cpv). Our approach in meeting the requirements of this credit are through Option 1, section 2 - "Provide a narrative describing..", as we cannot get design computations for the Stormwater management pond. Water quality is addressed on site with structural BMP\'s. Although the post-development discharge from this site is higher than the pre-development discharge because it is not managed on site, we believe we meet the credits\' intent by channeling Stormwater to a detention pond, managing quality with structural BMP\'s and protecting streams from Peak discharge rates.