The 2010 Census reported that the population of Albany, OR had grown over 50,000, requiring the city to meet Clean Water Act Phase II regulations. Phase II regulations require small municipal separate storm sewer systems (MS4s) and National Pollution Discharge Elimination System (NPDES) permits for stormwater discharges. The City of Albany hired Cardno to provide ongoing consulting / engineering services to develop a stormwater master plan.
Phase I services included providing recommendations for appropriate design storms utilized for modeling the existing and proposed storm sewer systems, as well as making recommendations regarding suitability for stormwater infiltration in areas throughout Albany.
Cardno analyzed the City’s existing stormwater detention practices and issued recommendations regarding which approaches would best fit the City. We created six detailed hydraulic models using the City's stormwater GIS data to quickly and accurately import data into modeling software. The models were calibrated to historical storms and include 100 miles of storm piping and 37 miles of creeks. Currently Cardno is working on Phase II services, and Phase III work will include existing system evaluation, future build out evaluation, develop detention standards and evaluate opportunities for regional detention facilities.
Challenges and solutions:
- apply conditions to meet a broad hydro-modification standard
- conducted stream assessments with respect to sensitivity to hydro-modification
- developed a hydraulic model using XPSWMM software and used the model to address hydro-modification and develop watershed specific standards
- complete a project started by another consultant
- performed detailed review of the existing work from the original consultant
- assessed incomplete work and completed that work by the given deadlines
- determine watershed specific criteria to protect streams for hydro-modification
- performed stream assessments to determine the flow rate at which hydro-modification occurs.