BIM Pairs with creative processes to eliminate project risks, cut costs for two Maryland developments.
Traditional earthwork estimating methods can come with risks for the developer and the contractor. Using surveying stakes and design plans, it can be difficult to estimate quantities to topsoil, other unsuitable material and structural fill. But a creative combination of new delivery processes and 3D Building Information Modeling (BIM) is reduce the construction risks for two developments in southern Maryland.
This unconventional approach was developed by construction management firm SmartSite, which uses BIM and GPS-aided accounting of the earthwork to figure contract scope and progress payments to the earth moving contractor. The BIM is a 3D model that shows several surfaces, including the original site topography, excavated surface to date, a temporary erosion control surface and the finished grade surface. In addition to SmartSite’s own GPS technicians, this system also integrates geotechnical engineers to gather topographic data with GPS rovers and data collectors, and report the information monthly to SmartSite and their clients. By contract, unit-price-based payments for earthwork are made accordingly.
Mining Dollars at St Charles Community
One of the development using SmartSite’s project delivery process is St. Charles Community a 9,100-acre master-planned community in Charles County, MD. Site Prep first reported on St. Charles’ use of this process, which replaced the hiring of a general contractor, in the August 2011 issue. The developer estimates saving at least 15 percent on site development costs, compared to the conventional general contracting approach.
Since that time St.Charles has seen other benefits to using this novel delivery approach. Besides providing accurate earthwork estimates, Sean Logan, SmartSite’s cost analyst and contracts administrator, says the 3D model also gives an as-built record of what has taken place for billing and change order reconciliation, and it allows the owner, contractors and utility companies to create an accurate locating system to identify the positions of underground work. Logan says this minimizes or eliminates the need to test pit to rediscover work performed.
In turn, the as–built model is helping the developer turn the earthwork into a potential source for revenue. At Fieldside and Gleneagles South, both St. Charles developments, the developer is mining and marketing sand and gravel for sale prior to developing the sites for housing. Rick Barnas, president of Barnas Engineering PC, says the BIM and GPS monitoring definitely make the mining process a lower-risk proposition for the developer.
“For previous mining sites that I’ve been involved with the over the years, basically you’re going in and you’re trying to dig out 20 or 30 feet of material, level the site off, then leave,” Barnas says. ”There’s no concept going in of where a house might be, a road might be, or anything. So you’re basically working blindly, and you take as much off as you can and do as little damage as you can.
“But the way it happens now with mining at St. Charles, the model indicates where the lots are going to be, where the roads are and so forth. We know exactly where we need to leave good material, and we know where structural backfill takes place and we know where we can use the material that is not structural. And then in terms of cuts, the model shows which areas can be over–excavated so that you get the most mining done without damaging the site below a certain elevation.”
As part of this approach, Geo-Technology Associates, a firm that perform geotechnical exploration, environmental studies, and constructions observation and testing services, drilled hundreds of exploration holes at St. Charles Developments to assess the depth of marketable materials.
“With St. Charles, there’s no set plan as far as where we start mining at,” says Matt Brown of Geo-Technology Associates. “That is where the GPS information is very valuable because the contractor will just mine down to a certain level to get all the materials they can. And from there, they start to refill it, and we need to get that information about where they stopped mining and start refilling — to determine how much fill is actually required. It’s a very different situation from normally-planned projects. The geology determines where the material strata changes and where we stop mining.”
Brown says BIM provides his firm with a progress report that tells where the contractor was filling each month and the current elevation on mining. “We can compare that information to our reports and make sure we’re all on the same page,” he says.
Another part of the project involved the testing of soil, asphalt and concrete for conformance with county specifications, conducted by Whitman Requardt & Associates of Baltimore. Paul Altman, a geotechnical field technician with Whitman Requardt, uses a Topcon GPS rover to record the location of tests. He says BIM definitely helps in his job.
“The model will tell me the finished grade of where the top of a building pad is supposed to be,“ Altman says. “so when I take my test, I know that they have 2 more feet to go, or 3 more feet, or if they’re at finished grade. I record the coordinates of my soil density tests, and I also list the elevation of where I took the test.”
“As great as all of these benefits are, perhaps the greatest benefit is the final phase when we transition from the mine stage to the finished development stage,” says Mark MacFarland, vice president of land development for St. Charles Community. ”Once mining is complete, we can finish the development
in less than half the time and risk as traditioanal delivery because most of the varying site conditions have been dealt with upfront”.
MacFarland says last year they delivered more than 100 lots in 60 days — from permit to turnover to the builder.
Better control at Chelsea Manor
Elsewhere in Maryland… Elm street development has put smatsite’s integrated delivery process for a 30 acre project. In 2012 general contractor Jimmy Richards and sons of Waldorf MD wrapped up $1.6 million of site preparation work at Chelsea Manor in Bryans Road, MD.
Doug Meeker, vice president at Elm Street says he’s always looking for ways to improve the business process to be more profitable and competitive. Meeker has known the leadership team at SmartSite for more than 10 years and that relationship led him to try their services.
“ I saw this delivery method as a way to not only lower my initial bid for site work but also as a way to control change orders and costs as we go through the project.” He says.
Smart site partner Frank Duduk says the delivery process at Chelsea Manor provides distinct benefits over conventional lump sum bidding.” We evaluate the scope more fairly by integrating experience and technology in a very easy – to – understand and transparent way.”
Duduk says, “with our prices it is virtually impossible for a negligent bidder to be awarded the job. And we think that’s good thing for our clients and the contractors we work with”.
For Chelsea Manor, Meeker says the first thing he did was contract with the design engineer, who prepared the construction plans required to permit and build the site improvements.
plans required to permit and build the site improvements. “When those plans were approximately 90 percent complete, I brought in SmartSite to begin the procurement phase of their scope of work,” he says.
He also contracted with a geotechnical engineer and a surveyor to provide the construction engineering surfaces. “Once SmartSite
finishes the procurement phase and moves into the implementation phase of their work, that is where I finalize the contracts with whomever the contractors are that I have selected to do the site work,” Meeker says.
One of SmartSite’s first tasks is to create a protocol document that sets standards for all clients and stakeholders who are going to use BIM. “It sets up a base of information of what they can expect, what information will be provided, how it will be laid out, what we are available to do, what we can offer them and so forth,” says Paul Gray, BIM manager at SmartSite.
SmartSite creates a preliminary construction budget and schedule, and analyzes general contractors’ bids to identify scope gaps, quantities and volumes compared to the BIM model. At the RFP stage, documents explain that payments to contractors will be made based upon field topo data that is integrated with the BIM. When the BIM is updated, SmartSite updates the project scope, quantities, volumes—as well as the preliminary construction budget and schedule. And SmartSite evaluates bids, levels out the inclusions and exclusions, and compares the leveled schedules of values to the preliminary construction budget.
In the implementation phase, SmartSite collaborates with the design and construction team and bidders to create value engineering solutions. Money may be saved by changing a method or procedure. The firm finalizes the construction budget based on the final BIM model and contract documents.
Every month during construction, the owner receives reports that lay out cuts and fills in many various areas, imported soil in several areas and unsuitable material management in several areas.
This topographic information helps contractors when it comes to billing, Duduk says. They can compare the new topo with the volumes of the previous month to ensure accuracy.
During the earthwork phase, the geotechnical engineer is on the site at all times conducting soil tests. Meeker says the engineer uses it to collect 3D points as he is doing his testing
“It was SmartSite’s idea to verify quantities,” he says. “The information that he collects is added to the model and SmartSite is produce progress reports on demand.”
Meeker likes the control that SmartSite’s reports give him. “First, they allow me to efficiently manage varying site conditions such as top soil, root depth and unsuitable material,” he says. “With the BIM, we can do fast and accurate evaluations—multiple `what-if’ scenarios to develop value engineering solutions. It helps steer the project in the right direction.”
While reporting topsoil strip volumes, Duduk says SmartSite realized Elm Street would need more structural fill material, and the job was already at a structural fill deficit—while also export- ing additional topsoil.
“This was a worst case scenario for our client— and timing is everything,” he says.
After a few hours, they were able to come up with a plan. Meeker says they had a large volume of unsuitable material that couldn’t be used in green space and other traditional areas.
“Using the model, we were able to calculate exactly how much of that material we had,” Doug Meeker, Patrick Hobbs and frank Duduk review the progress topes during a monthly progress meeting. This topographic information helps contractors when it comes to billing, nearly 10 percent of the contract’s volume, and about three to says. “We developed a plan to mine a couple of areas of the site that had an abundance of good material. We could use that good material to make site fills—and then fill the mine pits back with unsuitable material.”
Meeker says this saved Elm Street at least $150,000, which is nearly 10 percent of the contract’s volume, and about three to four weeks in project delays.
Daniel C. Brown is the owner of TechniComm, a communications business based in Des Plaines, Ill. For more information, visit www.technicomm.org