Company:

OC Public Works

Status:

Awarded

Awarded:

Flood Management Project of the Year

Additional Files

Brief photo slideshow showing various aspects of the project.

Additional Information

This system of projects reflects the spirit of Engineering in Orange County. They show how collaboration amongst various agencies to implement new approaches to engineering challenges can be utilized to for the betterment of citizens, commerce, and visitors.

Newland, Edinger, and East Garden Grove Wintersburg Storm Channel Confluence System

Project Location:

The project system is located within the cities of Huntington Beach and Westminster near the vicinity of the Newland Street Bridge overcrossing of Interstate 405.

Project Description:

The East Garden Grove-Wintersburg Channel, Edinger Channel, and Newland Channel all converge at the I-405 Freeway where the cities of Huntington Beach and Westminster share an intersection.  The project consisted of three phases: a physical hydraulic model of the freeway-channels confluence, the Edinger Channel project (which included a tunneling project under the I-405 Freeway), and the Newland Channel project which included over a mile of drainage improvements down the center of Newland Street.

Approximately 6,200 linear feet of channel were constructed for the Newland Storm Channel Improvements and approximately 3,300 linear feet of channel were constructed to improve Edinger Storm Channel (300 linear feet of this construction was tunneling beneath Interstate 405. The prime contractor for each of these projects was KEC Engineering; construction contracts were for approximately $15.4 million and $7.8 million dollars respectively.

Project Justification:

The East Garden Grove-Wintersburg Channel is the largest flood threat in Orange County and the subject area had suffered chronic flooding over the years ever since the I-405 Freeway had been constructed including widespread flooding in 1995 and again in 1997.  The improvements will assist in alleviating the overall drainage issues in the area upstream of the I-405 Freeway.  In addition, the Newland Channel project incorporated low impact development water quality features such as artificial turf and a debris capture system in the channel.

This project was unique due to its complexity.  The channel/drainage hydraulics were so complex that a $600,000 physical hydraulic model of the channel system at the I-405 Freeway was constructed to determine the hydraulic constraints for upstream improvements. Once the channel hydraulics through the freeway were determined improvements to Edinger Channel and Newland Channel could be designed with confidence.

In addition, the development and testing of the physical model allowed OC Public Works to develop water surface elevations for various channel geometries and configurations that could not otherwise have been developed using computer modelling techniques due to the complex geometries and flow regimes.

The Edinger Channel project required the addition of a 72"x113” elliptical RCP under the I-405 Freeway which required an extensive low height fill tunneling operation under the I-405 Freeway in addition to major drainage improvements upstream.

The final phase of the project included the construction of the improvements to Newland Storm Channel. This facility bifurcates its flow at the freeway, sending half of its flow to the East Garden-Grove-Wintersburg Channel (C05) upstream and the other half through a tunnel under the I-405 Freeway to confluence downstream.  The Newland Channel extends approximately 6,200 feet upstream in the middle of Newland Street, a very busy arterial highway in the cities of Huntington Beach and Westminster.  The drainage improvements included expanding the existing concrete trapezoidal channel to a larger rectangular channel and reconstructing drainage improvements under five street intersections requiring the redesign of each intersection.

Special Circumstances:

This complex system of projects required coordination amongst various agencies including the County of Orange, Orange County Flood Control District, CalTrans, the Cities of Westminster and Huntington Beach, and numerous utility agencies. The projects have been constructed in a manner that minimized or completely eliminated impacts to the motoring public. Complex traffic plans were developed to minimize impacts during construction on Newland Storm Channel within the middle of Newland Street. The construction of the Edinger Storm Channel improvements required a shored tunneling technique beneath Interstate 405 that utilized a laser topographic monitoring system that monitored displacements of the highway surface to within fractions of an inch.

Project Attachments:

This system of projects reflects the spirit of Engineering in Orange County. They show how collaboration amongst various agencies to implement new approaches to engineering challenges can be utilized for the betterment of our citizens, commerce, and visitors. This project in tandem with the larger ongoing improvements within the Westminster Watershed will help protect our community from the dangers of flooding.

Award Citation::

The East Garden Grove-Wintersburg Channel, Edinger Channel, and Newland Channel all converge at the I-405 Freeway where the cities of Huntington Beach and Westminster share an intersection. The project consisted of three phases: a physical hydraulic model of the freeway-channels confluence, the Edinger Channel project (which included a tunneling project under the I-405 Freeway), and the Newland Channel project which included over a mile of drainage improvements down the center of Newland Street.

Suggested Award Summary:

The East Garden Grove-Wintersburg Channel, Edinger Channel, and Newland Channel all converge at the I-405 Freeway where the cities of Huntington Beach and Westminster share an intersection.  The project consisted of three phases: a physical hydraulic model of the freeway-channels confluence, the Edinger Channel project (which included a tunneling project under the I-405 Freeway), and the Newland Channel project which included over a mile of drainage improvements down the center of Newland Street.

This project was unique due to its complexity.  The channel/drainage hydraulics were so complex that a $600,000 physical hydraulic model of the channel system at the I-405 Freeway was constructed to determine the hydraulic constraints for upstream improvements.  Once the channel hydraulics through the freeway were determined improvements to Edinger Channel and Newland Channel could be designed with confidence.  The Edinger Channel project required the addition of a 72"x113” elliptical RCP under the I-405 Freeway which required an extensive low height fill tunneling operation under the I-405 Freeway in addition to major drainage improvements upstream.  The third phase of the project included the construction of a facility that bifurcates its flow at the freeway, sending half of its flow to the East Garden-Grove-Wintersburg Channel (C05) upstream and the other half through a tunnel under the I-405 Freeway to confluence downstream.  The Newland Channel extends approximately 6,200 feet upstream in the middle of Newland Street, a very busy arterial highway in the cities of Huntington Beach and Westminster.  The drainage improvements included expanding the existing concrete trapezoidal channel to a larger rectangular channel and reconstructing drainage improvements under five street intersections requiring the redesign of each intersection.

The East Garden Grove-Wintersburg Channel is the largest flood threat in Orange County and the subject area had suffered chronic flooding over the years ever since the I-405 Freeway had been constructed including widespread flooding in 1995 and again in 1997.  The improvements described above will assist in alleviating the overall drainage issues in the area upstream of the I-405 Freeway.  In addition, the Newland Channel project incorporated low impact development water quality features such as artificial turf and a debris capture system in the channel.