Haster Basin is a 200-acre-foot retarding basin located on a 22-acre site in the City of Garden Grove.  The Orange County Flood Control District retained AKM to evaluate alternatives and prepare construction documents to allow the Basin to attenuate the 100-year expected value peak flow from the upstream (2,200 cfs) to the downstream channel capacity of 400 cfs.  AKM’s scope of work included the preparation of a comprehensive Preliminary Design Report, a Basis of Design Report documenting the steps and calculations used in the design of the project and the preparation of plans, specifications and an engineers estimate.  The final project included a 460 cfs pump station incorporating three 153.4 cfs mixed flow pumps operated by three 845 HP natural gas/LPG engines; re-grading of the existing Basin to increase its volume by 50 ac-ft; water quality features in accordance with the County’s Drainage Area Management Plan; various site improvements to facilitate  maintenance access to the facility, and joint use of the overall site as a community park with two soccer fields, and architectural enhancements to the pump station building consistent with the character of the surrounding area.  AKM verified the hydrologic studies and conducted hydraulic analyses of the East Garden Grove-Wintersburg Channel to ascertain that the outflow from the basin could be safely conveyed downstream.  AKM developed modifications to a 100-ft long section of the channel to increase its capacity from 400 cfs to 460 cfs, which in turn reduced the required flood storage volume and allowed the planning and construction of two soccer fields at the site.

The project also included 700 feet of a triple box culvert inlet drain (double 11.5’ W X 6’ H and a 9’ W X 6’ H). AKM processed the structural design of the pump station, channel modifications, and the triple box inlet channel through the County’s Building Department. AKM provided engineering services during construction, as well as startup and commissioning of the $26 million project.

The following is from an e-mail from Vincent Gin (former OC Public Works Project Manager) to Shane Silsby (former Director of OC Public Works) and Kevin Onuma (Deputy Director, OC Public Works Operations and Maintenance) regarding AKM’s performance on the project:

“More than most projects in my experience, the consultant, AKM Consulting Engineers, was especially emotionally engaged in the project.  Zeki Kayiran, John Logue, and Glen Deiter are not only technical experts in an esoteric and highly specialized field but performed beyond our expectations.  And we learned from them–our knowledge base is now greater than before expressly because of our work with AKM.  It was a privilege to work with AKM and witness their high level of competence, and I don’t say that easily about any consultant.”

-Kevin Onuma
 Deputy Director, OC Public Works Operations and Maintenance