Rock and Tight Quarters Complicate Work at Archer Hotel Site for J. Masterson
Deep excavation, substantial bedrock, and a tight site faced earthmovers for a "˜boutique" hotel under construction in the town of Burlington, Massachusetts.
"The Archer Hotel project is a rather complex site job with blasting, parking garage, big underground drainage system, and a tight site," said Bill Peach, P.E., Vice President of J. Masterson Construction Corp. Masterson is responsible for all site and building excavation and the installation of underground utilities at the Archer, a four-story luxury hotel rising in a development under the construction management of Erland Construction.
Matthew Combs is Erland's Project Manager for the new hotel that joins restaurants, retail businesses and housing in the mixed-use Third Avenue Development established by the Nordblom Company, the business park's owner. LodgeWorks Partners, L.P. are the owners and developers of the hotel, which is designed by LK Architecture, Inc.
Deep Basement Rock
Archer Hotel offers 147 guest rooms and suites, plus a restaurant, conference rooms, health club and swimming pool, and space for nearly 150 vehicles in surface and below-grade parking.
Excavation of the one-story, below-grade parking area, however, was not possible until a substantial deposit of bedrock was removed.
"This is where we encountered some of the deepest rock that required major blasting," said Steven Souza, Project Manager for Masterson. He added that other areas of the site also needed to have rock removed.
And with a number of occupied buildings close to the hotel site, a carefully executed blast plan would be necessary to minimize ground vibrations. This was provided by Maine Drilling & Blasting (MDB). Andy Dufore, MDB North Division Manager, described the task:
"The deepest cuts were up to 17 feet, and in some areas we were blasting only 90 feet from the nearest building," Dufore said. MDB used an Atlas Copco PowerROC T30 Percussion drill to bore 3-1/2-inch holes for the explosives. The blasting crew utilized a NONEL EZ DET 1.4B non-electric blast initiation system. Dufore noted that the primers were TROJAN SPARTAN boosters to optimize initiation of the BLASTEX water resistant, packaged emulsion explosives. He said that the average shot for the site covered about 1,500 square feet and yielded about 500 cubic yards of blasted rock, while the total amount of rock to be blasted and removed for the entire site was about 3,000 cubic yards.
Parking and Filtration Share Footprint
Masterson's contract calls for excavating the 30,000-square-foot building footprint together with its parking garage, and approximately 14,000 cubic yards of cuts and fills including areas of clay deposits between 3 and 5 feet thick. The contractor is also installing underground utilities including water, sewer, drain, electric, and gas lines; placing curbing, constructing sidewalks, access roads and new surface parking; and excavating and installing a 5,500-square-foot underground stormwater filtration system.
Surface parking and the filtration system are closely related and are the last major items to be built by Masterson. According to Souza, the filtration system has to be built first because it is located beneath the parking lot. But the 10-foot-deep excavation can't take place until sufficient excess cut material is removed from the site. Working quarters are so tight, there isn't enough room for stockpiles of soil and blasted rock so the material has to be exported to suitable offsite disposal areas.
The underground filtration, or retention/detention, system will capture area stormwater runoff so it can percolate into the ground. Since the system is underground, a parking lot can be built over it, thus increasing the amount of available land for the project.
Lightweight Chambers Capture Stormwater
Manufactured by StormTech, a division of ADS, the MC-3500 chamber system consists of lightweight corrugated plastic chambers resembling truncated beehives, and 24-inch diameter HDPE (high-density polyethylene pipe). The HDPE manifold pipes convey stormwater to the chambers, which are encased in stone - 9 inches below the chambers, 9 inches between the chambers, and 12 inches above the chambers. Excavation and installation of the filtration system have to follow these manufacturer's precise instructions:
After initial excavation, the contractor places non-woven geotextile over the prepared soils and up excavation walls, then places a 9-inch foundation of crushed stone on the geotextile. The foundation is compacted to achieve a flat surface, then manifolds are placed and woven scour geotextile is laid out at inlet rows at each chamber end cap.
Crews align the first chamber and end cap of each row with the inlet pipes and continue installing chamber rows by overlapping chamber end corrugations. Initial stone embedment anchors the lower portion of the chambers during construction. Manufacturer's installation specifications recommend the use of a stone conveyor or an excavator reaching along the row for this stage of the backfilling. No dozers or loaders are allowed on the bed at this time, and haul trucks are prohibited from dumping stone directly on the bed. Only after backfilling has reached at least 12 inches of cover stone over the chambers are skid loaders and small low-ground-pressure dozers allowed on the system to finegrade material.
A 2018 Target
Once installation of the filtration system has been completed, Masterson will construct the base of the parking lot, with Sunshine Paving Co. scheduled to lay the asphalt pavement. The site contractor has employed a variety of construction equipment at different times, depending on the varying nature of soils and the demands of earthmoving operations. Construction equipment has consisted of Caterpillar excavators including models 308, 320, 324, 330, 336; Volvo EL360BLC Excavator; Komatsu WA380 Loader; Caterpillar D5 Dozer; John Deere 250C Off-Highway Truck; and two Mack tri-axle dump trucks.
Masterson's equipment crews started earthmoving for the hotel in August 2016 and by June had completed about 75 percent of their site work. Developers expect the hotel to be ready for guests in early 2018.
About the Participating Companies
LodgeWorks Partners, L.P., headquartered in Wichita, Kansas, is a privately held hotel development and management company, that owns, franchises and/or manages branded hotels such as Archer, Hampton Inn, HYATT House, Hyatt Place, Aloft, and Hilton Garden Inn.
Erland Construction, with offices in Burlington, Massachusetts, and Hamden, Connecticut, provides construction management and general contracting services for new construction, additions, and renovations for residential, academic, office, commercial, and healthcare facilities.
J. Masterson Construction Corporation based in Danvers, Massachusetts, is a 30-year-old earthmoving company operating across Eastern Massachusetts and Southern New Hampshire.