Storm Drain Master Plan, Infrastructure Planning and Design
City of Dixon, California

West Yost performed a master drainage study for the City with complete review and analysis of applicable hydrologic models and development of a recommended Capital Improvement Program. West Yost also provided planning and design services for storm drainage infrastructure including detention ponds and pumping stations.

Storm Drain Master Plan

Services included evaluation of existing facilities and review of proposed new drainage facilities as part of assessment districts. Hydraulic design of detention basins, channel improvements and storm drains were also included in the plan development. West Yost assisted with the negotiation of a new discharge agreement with the downstream resource conservation district. A major effort in the study was to identify drainage from upstream agricultural lands. After identification, an evaluation of alternative means to control or bypass these flows through or around the City was conducted.

Subsequent to preparing the Storm Drain Master Plan, West Yost has provided the following additional services.

•Dixon Pond A Predesign and Design (600 ac. ft.)
•Sizing and Design of the Dixon Valley Glen Storm Drain Pump Station (160 cfs capacity)
•Dixon Pond C predesign and design (160 ac. ft.)
•On-Call Engineering Services and Development Plan Review
•Core Area Drainage Study

Storm Drain Infrastructure Design

West Yost performed planning of the expansion of Detention Pond A (from 200 ac-ft to over 600 ac-ft) and the Pond A Outfall (6 miles of open channel and culverts) by developing and evaluating three pond configurations and outfall alignments. Operation and maintenance cost estimates were developed and other non-cost issues were evaluated (such as environmental impacts and feasibility of acquiring right-of-way). An XP-SWMM model of the detention basin, existing and future tributary areas, and 6 miles of downstream channel was developed to provide the optimal final sizing of the pond storage volume, discharge rate, and the downstream channel and culverts. This resulted in implementation of an alternative that was $1.3 million less than alternatives the City had previously been considering. West Yost prepared the final design of this project and performed the construction inspection  and management for the project. West Yost also planned and designed a 160 cfs stormwater pump station for the Valley Glen development that lifts water into Pond A.

Additionally, West Yost prepared both the predesign and the design of Pond C, another detention pond facility that was identified in the original master plan. West Yost helped the City negotiate a revised discharge agreement with the downstream drainage agency, which reduced the required size of Pond C and saved the City about $600,000 in excavation costs. Based on the revised agreement, West Yost prepared the conceptual and final design for a 27 acre detention basin on a 40 acre site.

The project elements included a 160 acre-foot basin, a low flow inlet, a high flow weir, a discharge control structure, pond outlet piping, a maintenance road, headwalls, fencing, riprap, and local area drains. The pond was designed to use native California vegetation to develop aquatic, riparian, and upland habitats to attract a wide variety of wildlife. The project was constructed in two phases. Our cost estimate for both phases was $2.9 million, and the actual combined bids ranged from $2.3 million to $4.6 million. Engineering services during construction were also provided.