The original Folsom Dam in Folsom, California, received damage during a flood event that ripped gate structures from the top of the dam and destroyed large portions of the concrete spillway while attempting to rapidly release water from the reservoir. This four-phase project is designed to improve the ability to manage 200-year flood events by allowing more water to be safely released during storm events and leave more storage capacity in the reservoir when peak flows from the American River reach the reservoir. The Bureau of Reclamation and Army Corps of Engineers began the undertaking in January of 2008. The already-completed Phase 1 and 2 consisted of excavation for the new spillway, while Phase 3 is a new control structure. This article focuses on Phase 4 – the new concrete spillway which is being constructed by Kiewit Construction with the help of customized Sika Greenstreak PVC waterstop.

 

Prior to receiving the purchase order for PVC waterstop, Sika Greenstreak personnel met with the project managers and purchasing agents at the jobsite. The goals of these meetings were to determine the contractor’s main priorities, which were to minimize scrap material and field labor. The unique sales position of Sika Greenstreak lined up perfectly with the contractors priorities. The construction joint layout of the spillway is in 21-foot and 24-foot squares, depending on the slope of the channel.

PVC Waterstop Folsom Dam

Because Sika Greenstreak waterstop is normally run in 50-foot coils, this would have contributed to excessive waste of “drop-off” cuts. To eliminate this waste, Sika Greenstreak offered to run custom length coils for Kiewit. This simple idea saved over 4,000 pounds in scrap material. In addition, Sika Greenstreak’s fabrication department capability to hold tight tolerances was discussed.

 

It was proposed to Kiewit to create specially configured, long-legged crosses for the intersection of the slab construction joints and “Z” shaped fabrications for the step footing joints. According to a planning engineer for Kiewit, this approach would save Kiewit personnel from performing over 2,000 field welds on the project. Further, Sika Greenstreak also suggested the use of ST-10 field-welding tables to speed the field welding process and improve quality to meet the rigorous Army Corps of Engineers standards. No other waterstop manufacturer can provide all these benefits to a contractor! So, even though Sika Greenstreak’s basic cost per square foot was not as low as the competition, this creative savings approach, combined with technical field support and training, made the decision to choose Sika Greenstreak PVC waterstop an easy one.

 

An initial order was sent to the jobsite to aid in the construction of the half scale mock-up required by the Army Corps of Engineers. Kiewit had also designed a custom form work system to address the steep slope of the spillway. Suspended bulkheads forming “2 step” and “3 step” concrete pours will be used as construction moves down the extremely steep drop in the spillway in 100 cyd increments.

PVC Waterstop Folsom Dam
PVC Waterstop Folsom Dam