Soil type, planting medium and plant species must be considered for their capacity to promote infiltration. For example, clay soils do not allow for good infiltration rates and an engineered soil or compost could be added to allow for better absorption.

Consider contouring the land to direct stormwater to planting beds to reduce irrigation needs of potable water in locations where stormwater capture and reuse is not allowed. Parking lots and walkways can be graded to direct runoff to depressed swales or bioretention facilities with perforated pipes and other slow release infiltration mechanisms. This design offers better stormwater management than typical elevated or impervious planters.

The architect determines project eligibility for the building reuse credit based on pre-design assessment. A project is eligible if it is reusing an existing structure with no addition, or if the total gross square foot of the final project with the new addition would be less than two times the gross floor area of existing floor area. Use the Documentation Toolkit calculator to determine eligibility.

Treating captured stormwater to the quality standards required for this credit provides the potential for a clean water source for irrigation or toilet flushing, and a further reduction of the burden on municipal treatment facilities.

The stormwater design should reflect unique site features, attempt to minimize impacts on natural stormwater hydrology, and promote infiltration and treatment of stormwater runoff.

Previously existing stormwater management systems on the project site can be used towards credit compliance as long as requirements are met.

You must design any BMPs to local standards that have adopted an 80% TSS removal rate criterion, or use existing data that has monitored the TSS removal rates of different stormwater controls.

Find TSS removal rate data in state or local best management practice manuals.

The civil engineer and the landscape architect design the landscape and stormwater systems to maximize infiltration and collect water where possible. These systems must be designed based on the watershed region, and the BMPs employed must in combination remove 80% of the TSS for the post-construction design. The civil engineer will need to verify that the design meets the LEED requirements.

The civil engineer develops a stormwater management plan for post-development suspended sediment loads, detailing acceptable BMPs and their associated TSS removal rates. Reference the LEED 2009 Reference Guide’s table of Effectiveness of Management Practices for Total Suspended Solids Removal from Runoff. (Also shown here.)