Article No: 299

2011-07-14 11:22:56
CFA's BEST FOR 2011
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River City Foundations, a Concrete Foundation Association (CFA) member since 2005 from Louisville, Ky., won the CFA "Overall Grand Project Award for 2011," a 28,000-square-foot single-family private residence believed to be the second largest home in the area.

The sheer size of the foundation usually would normally send the owner looking for a commercial company to do the work instead of a residential company. But owner Bo Harrison said the homeowner came to River City Foundations for the project because of work the company had completed for the owner before, and because of its reputation for being the best at large and complex projects.

"This type of situation is what we excel at," Harrison said. "We are known for pulling off those 'impossible' jobs and doing it well."

"The completed foundation on this project is significantly different from the original blueprint," Harrison explained. "Major changes in the field meant countless hours of dismantling wall panels and redesigning new walls to meet the homeowners specs. You might say that the design aspect was a continuous work in progress.

"It had examples of almost every type of situation you can encounter in foundation work. Most challenges could be met with careful pre-construction planning; however, some had to be met in the field at that time."

The project has more than 1,500 linear feet of foundation wall containing more than 600 cubic yards of concrete and 41,000 pounds of steel reinforcement. The project includes a 12-foot walkout basement and a two-story, 24-foot-tall vault. Wall heights ranged from 2-foot 4-inch to 24-foot, and ranged from 10 to 15 inches in thickness.

River City poured footings that were all 3 feet wide and placed at a variety of levels with footing steps ranging from 8 inches to 5 feet in height. There were also special footings for a recessed elevator pad and the 10-foot by 15-foot vault.

"Typical of very large residences, the geometry and layout further complicated the construction," Harrison explained.

There are 11 individual radius or curved walls with radii from 2-foot to 38-foot 2-inch and a total length of 223 feet. The foundation also had freestanding columns up to 3-foot 4-inch square and 7-foot-tall, as well as concrete floors and ceilings in the vault.

"Approximately two weeks prior to the start date was spent proofing the blueprint, discovering errors and planning a schedule," Harrison said as he recounted the challenges. "We visualized how to stage equipment and designed ways to most effectively facilitate some of the more complex concrete placements."

Estimating was also a challenge and required multiple trips to the jobsite before elevation shots and layout could commence. Although significantly more detailed than a traditional set of plans and specifications, the architectural and engineering blueprints required intense scrutiny due to the level of detail involved with the full project.

Technology played a significant role in the success of the project for River City Foundations as they solved the complex layout of more than 700 individual points with a robotic total station. Concrete pumps delivered the concrete to much of the foundation due to the size and height of many of the wall areas.

"Being as the project schedule spanned different seasons, the working conditions varied from oppressive heat and mud to frozen ground and snow. Every day brought new challenges and new decisions," he said.

"We are blessed to have such a great work force of men and women," Harrison said. "I am very proud of the quality and pride that goes into all of our foundation jobs, big or small. I think this and many other reasons are why we maintain more than our fair share of the work in this market, despite the very slow economy."

SINGLE FAMILY RESIDENCE

Ekedal Concrete Inc., based in Newport Beach, Calif., won the 2011 award for a 13,000-square-foot single family private residence, also in Newport Beach.

The project started with drilled caissons at the rear of the property against the existing sea wall. Next, the existing sea wall was removed and a new sea wall location was placed.

v"We then started drilling 24-inch-diameter soldier piles, 32 of them in all, placing 162 yards of concrete," explained Vice President Ryan Ekedal. "The piles combined for a total depth of 1,303 feet and we excavated 220 yards of spoils."

Due to the water table, 22-inch casings were used on each hole to prevent collapse due to the presence of sand and water. When the correct depths were reached, the casings were pulled by crane and I-beams, which totaled 190,000 pounds of steel, followed by the caisson pours. This process required the use of a 10,000-gallon Baker tank onsite for the pumping of water and contaminants of each caisson location.

Because there was water in each caisson, the use of a tremie on the boom pump was key. This is a method where a long pipe is kept submerged in the water while concrete is pumped through it to the base of the pour. The rising concrete displaces the water until the form is filled. The project continued once all caissons and piles were in place.

"Well points were drilled to install and set up the dewatering system for the balance of the foundation construction," Ekedal said. "We had a total of eight well points, which were 30 feet deep, and we ended up pumping out well over 1,700 gallons per minute back into the ocean."

The pumps, powered by 75kVA generators, ran 24 hours every day, while onsite cameras monitored the process after hours to ensure the site was functioning properly and secure from vandalism.

Back-up diesel generators were on standby to take over if a power outage were to occur. Additionally, the team implemented a warning system to alert them if the water table onsite reached a certain elevation to prevent a catastrophic event on the property or any of the adjacent multi-million dollar properties."

All of this occurred before they could excavate the basement.

"During this (excavation) phase and the balance of our scope of work, we had a civil engineer come out and monitor the project's shoring walls to ensure we weren't sucking any sand out from beneath the neighboring properties due to the dewatering pumps," Ekedal said.

"Because of the massive size of the excavation and the soil conditions we were dealing with, we designed a lateral shoring system that included six 24-inch structural pipes set by a crane and welded into place horizontally, which went from property line to property line and remained in place until the walls were poured."

Ekedal said that once the lagging was installed and the bottom of grade (minus17 feet) was reached, the contractor poured a 77-cubic-yard, 4-inch waste slab that was then waterproofed with two layers of salt water paraseal. This was topped with a 60-cubic-yard, 3-inch cover slab to protect the waterproofing membrane from puncture during rebar installation.

"Initially designed as a slab on grade, we suggested a switch to a thick mat slab to further add weight because we were essentially building this large project floating on sand and water," he explained.

"We were then able to start the mat slab, which ranged from 27 inches to 36 inches thick and totaled 530 cubic yards of concrete with nearly 105,000 pounds of steel."

The team then moved on to the shotcrete and poured-in-place walls with two layers of paraseal applied. They formed and shot more than 200 cubic yards of concrete and placed another 65,000 pounds of steel for walls that were 11 feet tall and 12 inches thick. Finally, they set up and poured structural deck in some of the key areas.

"This is definitely one of those projects where all of our experience, pre-construction planning, and design comes into fold and plays a major part in the success of the project," said the vice president of the company that has built award-winning homes in seeming impossible sites all over the West Coast.

"Building a basement of this size, essentially on water at 17 feet below sea level, surrounded by million-dollar homes challenges us to live up to our motto of 'Perfection.' We lived up to it again."

ABOVE GRADE

Who says you can't build an award winning home by committee?

Winning the 2011 CFA award in the Above Grade Category are Basement Contractors and Herbert Construction Co. for a two-story home in Bush, La., that came together with the precision teamwork of CFA members in several states.

The combination of Basement Contractors of Oklahoma, Herbert Construction of Georgia, Purinton Builders of Connecticut and Thermomass prove that collaboration and high-quality construction can overcome the challenges of design and location.

This unusual project began with an inquiry to CFA member Purinton Builders as a distributor for CFA member Thermomass. Purinton officials referred the owner to CFA member Mike Hancock of Basement Contractors.

Hancock said he then realized that having a partner located closer to the project and one that might be able to handle the schedule of the project would be advantageous and he quickly brought in CFA member Barry Herbert, president of Herbert Construction of Georgia.

"The CFA network delivered a complete solution as we were responsible for the construction of the walls, and Basement Contractors provided deck construction design and assistance, and placed all flatwork," Herbert said. The general contractor, Clayton Kresge, was instrumental in choosing Thermomass for the project and was very happy with the completed project. Purinton Builders was the distributor for the Thermomass insulating system."

The home is two stories, in addition to a full terrace-level walkout basement. There are two two-car garages, one of which was over a structural concrete slab to create a safe room in the terrace level.

The rear porch was an elevated structural concrete slab, while the rest of the home had conventional wood flooring. The typical first floor wall height was 12 feet and rose to 24 feet 3 1/4 inches; and the typical second story wall height was 10 feet 9 1/4 inches tall. The concrete walls ranged from 10 inches to 18 inches thick.

There were also many gable ends in the exterior walls that were formed and poured in concrete. The project actually included nearly 1,500 cubic yards of concrete and more than 86,000 pounds of steel reinforcement.

Outside the all-concrete house, the team also constructed more than 100 feet of 15-foot 3-inch-tall serpentine retaining wall to support the site development. The number of openings and services increased the complexity of the wall pours for Herbert. In all, there were 85 window and door openings in the exterior concrete walls, many of which were arched.

There were more than 200 electrical boxes for switches and outlets in the wall forms that were then cast monolithically in the concrete, according to Amanda Morris, vice president of operations for Herbert Construction.

"The owners and architect chose a concrete home for its energy efficiency, indoor air quality, immunity to termites, resistance to hurricane-related winds, and overall security," Morris said.

This project was difficult for the team to reach from their home bases. Located in Bush, the job was 10 hours away from Herbert Construction. Herbert said forms and much of the equipment were shipped to the site by common carrier.

"While we were on location for several weeks the temperature hovered around 105 degrees with humidity in the 90s," he said. "The area was experiencing one of its wettest years, which complicated the project with rain and mud."

In all, the network approach to this project combined with additional technology of Robotic Total Stations and a computer-aided design (CAD) system designed specifically for foundations allowed the efficient communication from the office to the jobsite to deliver an efficient construction and a striking residence.

ADDITIONAL CFA HONOREES

MPW Construction Services won the CFA Commercial/Multi-Family Award for five units in the 11 River project on the banks of the Rocky River in Rocky River, Ohio. River waters were as close as 10 feet to the foundation lines, and at the front of the units, the foundation walls were within 25 feet of a hillside that rose vertically 75 feet to the houses above. Concrete Monthly will profile this project in the August/September issue of Concrete Homes.

Honorable mentions, both in the Above Grade category, included the Greenbuild Legacy Project by Biltmore Insulated Concrete Inc., and the Lytle residence by Basement Contractors Inc.

Information for this article was supplied by the Concrete Foundation Association's Concrete Faces, Vol. 18 No. 4.