Drainage Investigation and Flood Analysis for Whitwell Avenue Area Watershed
The drainage watershed that encompasses Whitwell Avenue and the surrounding neighborhoods has experienced an increase in street flood events during rain events of high intensity. The storm drainage system in the area discharges into the Moat at Ellery Road.
The City awarded a contract in April, 2016 to conduct a drainage investigation and flood analysis for the Whitwell Avenue and surrounding neighborhood area to identify the causes and to develop short- and long-term mitigation measures. The investigation will consider observations made during recent street flooding events and trends in extreme precipitation events.
The first public informational meeting for the project was held on June 1, 2016.
The second public informational meeting for the project was held on December 7, 2016.
The City's engineer for the project, Fuss & O'Neill, has submitted their final report for the project which was outlined at the December 7, 2016 public meeting. The City thanks all the stakeholders that provided valuable input for the project.
Drainage Investigation and Flood Analysis for Wellington Avenue and Bridge Street
When the neighborhoods along Wellington Avenue and Bridge Street were first developed hundreds of years ago, their locations close to Newport Harbor were seen as a benefit. As time progressed more homes and businesses were established and the City installed storm drainage infrastructure in these neighborhoods and throughout the City. The investments in storm drainage infrastructure have served the City well for decades, and in many areas still provide adequate storm drainage even during the largest and most intense precipitation events. Recently, the Wellington Avenue and Bridge Street neighborhoods have experienced what is perceived to be more frequent and more severe street flooding events.
In 2015, the City conducted a drainage investigation and flood analysis for these two locations to identify the causes and to develop short- and long-term mitigation measures. The investigation considered observations made during recent street flooding events and trends in sea level, tidal cycles, and extreme precipitation events.
The City maintains a project specific website for this project which can be accessed at www.newportdrainageinvestigation.com
The project website includes:
- Project Information
- Evaluation of Typical Year Benefits
- Final Report
- Public Informational Meeting Presentations
Easton Beach- UV Disinfection System
The Easton Pond Dam & Moat Study reviewed and presented long term water quality alternatives for the moat outfall onto Easton Beach. The long term alternatives involve major capital improvements and construction.
Based on the evaluation of the alternatives, Fuss & O'Neill recommended that the City implement an Ultraviolet Light (UV) disinfection system to treat the discharge from the moat after a storm event prior to it mixing with the water at Easton Beach.
However, there are several variables that need to be better defined prior to proceeding with a design of the system. It was further recommended that the City conduct a pilot testing program. The purpose of the pilot testing was to confirm that UV disinfection could significantly reduce bacteria loadings being discharged from the moat after a storm event as well as to collect data that would be required for the final design of a full scale system.
The City amended the contract with Fuss & O'Neill in June 2007 in order to proceed with the pilot testing for a UV disinfection system. A trailer mounted UV pilot plant was operated by Fuss & O'Neill from September through October 2007. The results of the pilot study are presented in the report.
The results of the pilot study confirmed that UV disinfection could significantly reduce bacteria loadings being discharged from the moat during a storm event onto Easton Beach. While the pilot testing has confirmed that UV treatment is practical, several design issues need to be resolved as part of preliminary engineering such as: system layout and hydraulics; determine if pretreatment required; determine subsurface conditions; dilution factor; and electrical power requirements.
The City amended the Contract with Fuss & O'Neill in June 2008 for engineering design services associated with advancing the design of a UV system to a 60% level. A presentation of the preliminary design status was presented at a City Council Workshop on October 16, 2008. The preliminary design report was completed and is presented below.
- Council Workshop October 16, 2008 Presentation
- UV Disinfection Preliminary Design Report, November 2008
- UV Disinfection Preliminary Design Report, November 2008 - 2
- UV Disinfection Preliminary Design Report, November 2008 - 3
- UV Disinfection Preliminary Design Report, November 2008 - 4
The City amended the contract with Fuss & O'Neill in February 2009 to proceed with the final design and permitting in preparation for the bidding process for construction. The final design was presented at City Council workshop on August 25, 2009, prior to submitting permit applications for the project to the applicable regulatory agencies. A final City Council Workshop on the UV Disinfection Project was held on November 19, 2009.
The UV Disinfection Project will be advertised for bids beginning December 4, 2009. Construction bids for the project are due January 7, 2010.
Easton Pond Dam & Moat Study
In September, 2006 the City Council awarded a contract for engineering services to Fuss & O'Neill, Inc. for the Easton Pond Dam & Moat Study.
The work included an assessment of the dam and appurtenant structures which form North and South Easton Pond and an evaluation of the drainage moat which surrounds the dam.
South Pond Spillway
The City has identified the Easton Pond dam and its integral drainage moat as a vital piece of the city infrastructure for both its drinking water and storm drainage. Easton Pond consists of North Easton Pond and South Easton Pond totaling 112.7 acres and 147.5 acres respectively.
The north and south ponds are separated by an earthen embankment and connected by pipelines through the embankment. The ponds are two of the raw water reservoirs used by the Newport Water Division. Water from these reservoirs is treated at the Station 1- Water Treatment Plant located on Bliss Mine Road. The Easton Pond has served as a raw water source dating back to 1877 and is a vital part of the Newport Water Division's infrastructure.
The last significant work completed on the dam was reconstruction of the spillway and south bank of the dam in 1939.
A drainage moat encircles the South Pond Dam starting at Station 1- Water Treatment Plant and discharges under Memorial Boulevard to the Atlantic Ocean at Easton's Beach in the same area of the spillway for South Pond.
The shallow, nearly flat ditch (moat) was apparently constructed to carry runoff from an area northwest of the pond and flow from the emergency spillway of North Pond.
Prior to the new Station 1 coming on line in 1991, filter backwash water and sediment from the sedimentation basin cleaning were discharged into the moat.
These discharges are now discharged directly to the Bliss Mine Road Sewer Pumping Station. Over the years with the development in the City, the moat has also become a discharge channel for numerous storm drains. During significant rain events the capacity of the moat is exceeded and area flooding occurs which at times leads to road or travel lane closures.
- Easton Pond Dam & Moat Study
- Easton Pond Dam & Moat Study - Appendices
- Easton Pond Dam & moat Study - Figures