Taming a Flood-Prone Creek
Taming a Flood-Prone Creek
Twice named an All-American City, Sioux City, Iowa serves as the regional hub for Northwest Iowa, Southeast South Dakota, and Northeast Nebraska. More than 140,000 people live in the tri-state metropolitan area.
Meandering through Sioux City’s near west side and city center is five-miles of Perry Creek, a catchall for the city’s storm water. The picturesque creek eventually empties into the Missouri River. Even though the creek is 20 feet above the water table, it runs with approximately two-feet of water everyday, and is prone to flooding on a semi-regular basis with significant property damage resulting.
City partners with Army Corps
In the mid-1980’s Sioux City partnered with the U.S. Army Corps of Engineers to study and develop a plan to widen the channel and in some cases redirect it. In cities near waterways, the Army Corps has been instrumental in constructing floodwalls, levees and diversion channels to keep storm water out of homes, schools and businesses.
The Army Corps of Engineers is directing the Perry Creek project, which consists of 14,800 linear feet of grass and rock lined channel, 1,500 linear feet of new conduit, modification of 710 linear feet of existing conduit, a concrete stilling basin and a basin-wide flood warning system.
The Corps contracted with Western Contracting Corporation of Sioux City to coordinate Phase 4 as the general contractor. Western, in turn, subcontracted with Peterson Contractors Inc. (PCI), based out of Reinbeck, IA, to the excavation portion and installation of the riprap on the project.
“We’re on Phase 4 of this lengthy reconstruction project,” said Jason Billerbeck, GPS superintendent, for PCI. “Phase 4 which we are currently working on is about two miles. We’re cleaning up the channel in some parts and redirecting the creek in other parts.” Some sections of the creek channel require digging to 30-foot depths.
“The SCS900 saves me an incredible amount of time. It literally saves 80% of the time it should take.”
– Dave Horstmeyer, quality control manager, Western Contracting
An estimated 540,000 cubic yards of channel excavation will be required with approximately 376,000 cubic yards being trucked off site. Daily quantities are between 300 and 350 truckloads, with each truckload being between 12 and 13 cubic yards. To provide the Corps and the general contractor with a comfort level on the ongoing progress, PCI issues a topo report that compares load counts in the 12 to 14 side-dump and belly-dump trucks to the actual excavation amount removed.
Real-time topo volumes required
“We rely on technology to get an accurate reading on the amounts of dirt being removed,” stated Billerbeck. “With the Trimble SCS900 Site Controller System, we’re using GPS positioning technology to measure material volumes. This job requires so much topographical mapping – we can record volumes as we go…real time. It saves a lot of time versus having to download measurements in the computer and opening it up into a program like Trimble’s Terramodel to figure out the quantities. I can walk an area with the SCS900 mounted on a rod and know exactly what volumes are involved. There are far fewer steps involved in obtaining the data.”
Billerbeck continued, “Since I take a lot of topos, the SCS900 is nice because it has a little map display and fills in the data for you. The system gives me a better picture of where I’ve been and can actually generate contours to indicate if there are missed spots that need to be filled or to show any hills or valleys. The best thing is the SCS900 confirms that the job is being completed according to plan.”
The SCS900 system was used early in the project as well. “The first thing we did is literally put on a pair of hip-waders and walked the creek, slopes and tops to get an accurate topo – using the SCS900,” Billerbeck said. “We also save a lot of time in staking and don’t have to scale off the plans – they’re right on the SCS900. Before, if you wanted to find something on the plan, you either had to know the distance from a set point or you had to scale something off by knowing where two manholes were, for instance. So, I’d spend more time sitting and scribbling to figure things out.”
GC Also Uses SCS900
Dave Horstmeyer, quality control manager for Western Contracting Corporation, also uses a SCS900 on the project. “I’ve used it for plotting boundary lines, staking out retaining walls, establishing right of ways and even for tree removals. The fact that it’s so very portable means I literally can have the entire project plan in my hand and see exactly where I’m standing relative to the plan.”
“We rely on technology to get an accurate reading on the amounts of dirt being removed. With the Trimble SCS900 Site Controller System we’re using GPS positioning technology to measure material volumes.”
– Jason Billerbeck, GPS superintendent, PCI
If Horstmeyer wishes to, he can even monitor PCI’s progress by comparing the design elevation to the actual cuts and fills that have been completed.
“The SCS900 saves me an incredible amount of time,” Horstmeyer said. “It literally saves 80% of the time it should take.”
GPS Also Used in Grade Control
Peterson Contractors also uses a GPS system for grade control on its Caterpillar D6 track-type tractors that are deep in the channel completing the grading before the creek bed gets lined with bedding stone followed by a layer of small stone and then topped with limestone rip-rap.
“We have the Trimble SiteVisionTM GPS system running on the dozers,” Billerbeck said. “We literally save twice the work. We can rough in the creek bed and accurately finish it in almost no time. Before SiteVision, we’d rough it in, stake it, half finish it, and stake it again – to be honest, we’d end up staking it three or four times and hopefully get everything close enough to call it good.”
Published in Trimble Productivity, Winter 2004 (Customer Profile)