In an old farm field near New Carlisle, Indiana, a new kind of ‘plant’ is growing. It did not require a tractor and plow to take root, but a multitude of Putzmeister truck-mounted concrete boom pumps and Telebelt® telescopic belt conveyors to construct seven large foundations and multiple smaller ones for a new plant that will produce electricity, one powered by natural gas instead of coal.
Phase I of the St. Joseph Energy Center construction project involves building a 700 megawatt greenfield natural gas-fired, combined-cycle power plant. The waste heat from the gas turbines will be used to power the steam turbine and for generating additional electricity without using more fuel. The heated water, which is the by-product from the process, will be cooled in cooling towers and cycled back to feed the power plant. Plans call for an identical second phase, resulting in an estimated total project cost of a half billion dollars.
So many construction trailers have been assembled, the 165-acre job site looks like its own village. Masterlink Concrete Pumping LLC of Northwest Indiana is one contractor frequently seen on-site, providing both the backfill and concrete placement services for the high-profile project, which is under the direction of Kiewit Power Constructors.
“Building a power plant depends on time and schedule; there is no leeway for downtime,” said Mark Ansin, Concrete Structure Lead Superintendent of Kiewit. “That's why I specifically visited three local pumping companies and three local concrete suppliers to find dependable equipment and services.”
“I've done thousands of pours with Putzmeister pumps, and they've always been reliable,” adds Ansin. “The brand is important in the selection process; however, I always check that the pumping company keeps its equipment well maintained.” Masterlink's fleet passed the inspection, and their company's documented maintenance program was even reviewed, which was an added plus.
Masterlink, under the ownership of Steve Slater, additionally brought 12 years of experience placing concrete, highly trained ACPA-certified operators, and a wide range of different sized concrete boom pumps, conveyors, and trailer pumps. Once awarded the job, they went right to work to meet a fast-paced six-month deadline for completing the foundation work.
In March 2016, the placing company pumped their first yard of an estimated 28,000 total cubic yards (21,408m³) of concrete for Phase I. They also placed their first ton of an indefinite but colossal amount of sand and stone needed as backfill during the project.
Pump Sizes Grow
Initially, an exorbitant amount of duct banks, designed to protect the electrical wiring, were installed underground. With a basically barren site, the conveyor could easily find a place to setup and backfill around the duct banks, and then the 32Z- and 38Z-5-meter boom pumps encased them in concrete. However, as the project advanced, the site became more congested with a maze of underground piping to maneuver around. To accommodate, the larger 40Z- and 47Z-meter models, at 128'3" (39.10m) and 151'3" (46.10m) vertical reaches respectively, were dispatched as the reach requirements grew greater.
Although there are countless foundations and varied areas that need concrete placement, seven large sized foundations took center stage. The size and complexity of the foundations were all different; however, the process is similar for each—digging a deep hole, backfilling with sand or stone, placing a six-inch (152mm) mud mat, erecting tall forms and pumping concrete up to a four-and-a-half foot (1.37m) thickness. Pours range from 600 cubic yards (459m³) for the smallest pour to 1,500 cubic yards (1,147m³) for the largest.
“Every power plant has its own set of challenges, but the foundation always has to be exact,” says Ansin. “For instance, when we cast huge anchor bolts into a foundation, these bolts have to be within a 1/32 of an inch in matching up with the plant's machinery that will set on top of them. There's no room for error when placing concrete to avoid losing such a complex foundation.”
The concrete pours have been going like clockwork to handle an array of foundations with code names such as HRSG, CTG, STG, etc. Typically, a 4,500-psi (31 MPa), seven-inch (178mm) slump concrete with superplastizers is used that allows concrete to easily flow through the pump and rebar. However, the CTG foundation, where the steam turbine engine will set upon, is one foundation that specified a different mix.
“We used a hydration stabilizer, which causes a chemical reaction that basically put the concrete to sleep for four hours. It is a dual purpose product that acts as both a type D water reducer and retarder,” said Jim Sellers, Quality Control Manager at Kuert Concrete of South Bend, Indiana. “The technology has been around for more than ten years, but more contractors are just now being introduced to the hydration stabilizer by the ready mix industry.”
The hydration stabilizer is very potent so it is very important to add the precise amount to the mix based on the time delay desired. Its benefits include providing good consolidation without cold joints, allowing finishers ample time to finish a job, and offering a precautionary measure in case of delays or problems so the entire foundation is not lost.
Layer after Layer
For the CTG pour, concrete promptly arrived at 2 a.m. in the morning to beat the summer heat. From one setup location, two boom pumps - a 40Z and 47Z-meter - set up at opposite ends of a 50 foot by 115 foot (15.24m x 35.05m) area that required a four-and-a-half foot (1.37m) concrete thickness.
Pumping concrete from their respective edges and meeting in the middle, the team of pumps pumped a third of the special concrete mix at a time, placing the bottom, middle and then top layer. As a result, 600 cubic yards (459m³) of concrete was pumped in four hours.
The ready mix company recorded dispatching concrete up to 280 cubic yards an hour (214m³/hr) from their high output central mix plant in South Bend. Ansin said, “The pumps pumped the concrete as fast as it was delivered, which is important as we want to get at least 120 to 130 cubic yards an hour (92 to 99m³/hr) for these large pours.”
Predicting future setup challenges, Jason Rapley, Sales Manager at Masterlink, notes, “As more foundations are built, there are different structures being worked on at the same time so it's going to be tricky to coordinate upcoming pours. We will need to find both a path to get to the next pour and one that allows for efficient ready mix truck flow. We definitely need our bigger boom pumps, such as the 52Z-meter with its longer 170 foot (52m) reach.”
The Telebelt TB 105 and TB 110 conveyors, with 105 and 110 foot (32 and 34m) horizontal reaches respectively, have been conveying a mammoth amount of sand and stone as backfill.
The conveyor is kept busy placing backfill almost every day of the week. “Our Telebelt has been the answer to this project's enormous backfill needs. I have absolutely no idea how Kiewit would have been able to backfill as efficiently using anything else,” said Rapley. At one point, the conveyor even had to build its own ramp with backfill to ironically access an area that needed backfill.
Capable of conveying at high outputs up to five cubic yards a minute (3.8m³/min), the conveyors quickly place sand and stone exactly where needed, under sloped pipe edges as well as around and over pipes that were five foot (1.52m) in diameter. Once finished with a section, the boom pumps take over to place concrete.
Electricity on its Way
The output from Phase I will be capable of serving approximately 450,000 households and is expected to generate approximately 500 jobs during the construction phase and 25 permanent jobs when it comes online in the first half of 2018.
Owners/Developer: Ares EIF Group, a subsidiary of Ares Management; Toyota Tsusho—St. Joseph, Illinois; and Development Partners Funding
General Contractor: Kiewit Power Constructors—Lenexa, Kansas
Concrete Placing Contractor: Masterlink Concrete Pumping LLC—Merrillville, Indiana with service operations in Chesterton, Plymouth and Indianapolis
Ready mix supplier: Kuert Concrete, Inc.—South Bend, Indiana
Equipment: Putzmeister 52Z-Meter, 47Z-Meter, 40Z-Meter, 38Z-5-Meter, and 32-Meter truck-mounted concrete boom pumps; Putzmeister Telebelt® TB 105 and TB 110 telescopic belt conveyors