NV5 - Z-Drain Bridge

“Z-Drain” Bridge

Upon request by the County, NV5 inspected the old 5-span timber bridge and recommended complete closure based on the following deficiencies: (1) Abutment 1 piles and Pier 2 piles are out of plumb and exhibit vertical cracks; (2) Abutment 1 and Pier 2 cap beams have rotated with the deflected piles, causing span 1 to shift to the south; (3) Underground seepage through Abutment 1 bulkheads is slowly causing further deterioration of the piles.

Due to the urgency and political pressure to re-open this roadway to traffic, NV5 staff, in cooperation with County staff, prepared a full set of plans, specifications, and estimate (PS&E) for repair in two weeks.

Upon submittal to the County, we received a phone call from the Director of Public Works, commending our efforts in producing such a complete set of construction drawings in a very short period of time.

Unfortunately, due to heavy rain storms that caused additional erosion at Abutment 1, span 1 collapsed one week after a contractor was selected to perform the repairs. The County immediately tasked NV5 with the design of a new bridge to replace it. To avoid encroachment onto Imperial Irrigation District’s right of way, we designed a single span bridge using precast I-Girders. Construction was completed with design support from NV5.


County of Imperial, CA


County of Imperial