Watearth, Inc. worked on the forward-thinking drainage criteria manual that plays a crucial role in protecting and restoring the health of the City’s watersheds as well as protect the City’s investment in stream restoration and natural channel design projects. Updates to the DCM were incorporated into City code following City protocols and code update processes. Watearth performed a literature review and data evaluation related to methods used nationwide to address excess urban runoff volume. Watearth provided recommendations for stormwater control/management strategies to achieve volumetric detention goals for the City of Austin. Project recommendations complied with federal, state and local regulations for stormwater quality. Developed Volumetric Design Procedure criteria. Recommended incorporation of Green Infrastructure and Hydromodification Management techniques. Developed guidance and criteria for developing stage hydrographs and tailwater criteria for detention routing. Performed peer review of natural channel design criteria revisions.
Efforts included an initial development starting in 2015 and NOAA Atlas 14 updates in 2019.
NOAA Atlas 14 updates involved HEC-HMS modeling (hydrology) and an evaluation of the effect of rainfall distribution on peak flows and estimated detention volumes for the 25-year and 100-year rainfall events using updated NOAA Atlas 14 rainfall depths. Utilized multiple distributions for various Walnut Creek watershed locations and small, medium, and large size developments. Recommended distribution for use in City modeling. Prepared technical memorandum. Presented results to internal and external stakeholders.
