Shared stormwater best management practices (BMPS) collect and manage stormwater from several properties, typically saving space, money and maintenance costs.

Benefits and Problems Addressed

Constrained lots: Shared facilities help  to manage stormwater where lots are too small to handle required rainfall volumes or where soil or groundwater conditions preclude 100% infiltration on an individual site. 

Reduced costs: Multiple landowers share the costs and maintenance burdens.

Facilities that house multiple uses:  Shared stormwater management can be designed into other facilities such as parks and landscaping.

Overflow: Shared use facilities can serve as emergency overflow in an area; this is likely to grow in importance with expected increases in  extreme storm events.

Tips & Techniques

Identifying shared-use facility locations: Shared systems work best in space-constrained areas where handling stormwater on individual properites is infeasible.
Identifying candidate site for multiple uses: Look for multi-use design (e.g. landscaping, parks). This can occur early for facility updates and renovation.
Cost and maintenance allocation: Design should allocate costs fairly, for example amount of stormwater discharged and/or treated.
Hot Buttons: Requires contracts among property owners to ensure proportaional responsibility and financial support.  Also includes shared liability.

Example

The Highline - New York City, NY, USA
11th Street Bridge Park - Washington DC USA
 

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