Our project is seeking a ruling for LEED CS 2.0 WE credit 1.1-1.2, in regards to the specific circumstances for this project to recycle stormwater from a large manmade lake for landscape irrigation purposes and earn both WEc1.1 and 1.2. Background Our site is located on a former rock quarry. The quarry has been partially filled and flooded leaving a deep 12 acre manmade lake which is being recharged by runoff from a large adjacent urban zone. The project has incorporated native and adaptive species to reduce the landscape irrigation calculated total applied water use by over 50% and intends to utilize water from the non-potable source lake water for supplemental irrigation purposes to achieve both WEc1.1 and 1.2 through a 100% reduction in potable water use. A previous CIR ruling dated 9/5/2008 referred to a project that must document the stormwater coming in and going out of a pond to determine if the pond can meet the needs of the building and to compare projected pond levels to historical data. We have calculated that across the entire lake (530,996 sq. ft.), there would be a 0.274 inch/month drop due to irrigation use. The lake is being backfilled by a quarter acre to accommodate this project which will create a smaller basin and higher flows into it. Due to the dense urban surrounding of the project, we believe the runoff will easily accommodate this irrigation use. Calculating the inflows and outflows for the lake is not possible due to the unknown extent of the urban zone that is recharging the lake and historical data on the lake is not available. We intend to submit the LEED application within a short timeframe from the buildings opening and due to time constraints will not be able to verify performance of the irrigation system through measurements before the project submits. We intend to submit this credit in LEED online with the requirements as stated in the LEED CS reference guide and we would like a ruling as to whether our strategy will be sufficient to earn both WEc1.1 and WEc1.2 and if not, is there an alternative compliance path the project can take that does not involve a performance measurement time period.
The project is asking if a manmade lake, recharged with runoff, can be used for irrigation as a non potable water source, and count towards WEc1.2. It is unclear if the lake serves other uses, and if groundwater recharges the lake. If there is any groundwater present in the lake, then all three conditions of the 9/5/2008 CIR must be met. If the team can demonstrate that the lake is exclusively fed by stormwater, then stormwater and irrigation calculations must be provided for this and any future projects that may draw from the lake, indicating that over the course of the year, the water used for the project will not exceed the stormwater collected in the lake; and that in every month of the year the projected level of the pond shall not drop below historical average pond levels. Applicable Internationally.