stormwater runoff report

[brockelbank]

Could you please explain to me what the $amount stands for on the report. Is it the amount of money the city will save for construction to contain storm water or entirely something else. And how is the default set up to be used for the calculation.

[smaco]

The dollar value for stormwater interception is different for each climate zone in STRATUM. The origination of these values are chronicled in the Tree Guides. Each STRATUM climate zone is represented by a specific Tree Guide, which describe the underlying research methods and tree growth models used to develop benefit valuations of street trees within the STRATUM application. The USFS Community Tree Guides can be accessed from the Resources - Archives page http://www.itreetools.org/resources/archives.php under the i-Tree Streets Reference City Tree Guides tab

--Scott

[brockelbank]

The tree guide explains the benefits of trees in relation to stormwater collection, and mentions a dollar amount for these benefits. But it does not explain what that dollar amount is related too. Can you please explain what the dollar amount represents? Thanks

[smaco]

Below is an excerpt from the Northern Mountain & Prairie Tree Guide (Appendix B, pp. 82-3):

"To estimate the value of rainfall intercepted by urban trees, stormwater management control costs were based on construction and operation costs for a recently built detention/retention basin in Fort Collins, CO. The drainage area was 660 acres (267 ha). The basin was designed to hold 17.2 acre feet (21,216 m3) of runoff and cost $1.04 million to construct (McBride 2002). With operating and maintenance costs of $700/month for 20 years, the total project costs were $1.21 million. Assuming that the basin filled once annually for 20 years, the control cost was $0.0108/gal ($0.000041/m3)."

The methodology will differ by climate zone, so be sure to check the Tree Guide for your area.