The Liebherr makes light work of a Jersey barrier.
Unless you are a seagull or a yacht, there is only one way to access Nahant Beach, Mass. — a beach with a heavily traveled causeway and public access areas in desperate need of rehabilitation.
To that end, Pihl Inc., a Denmark-based company with U.S. headquarters in Canton, Mass., is completing the seventh phase of a delicate seven-phase, $20 million, four-year beach access and rehabilitation project.
The Nahant Beach Reservation Rehabilitation Project, which began in May 2010 and is expected to be completed in May 2014, has required careful digging and temporary road building to accommodate the beach-going public and to preserve the fragile and protected wetlands that surround the excavation work.
It is a challenging endeavor that has required 13 subcontractors under Pihl Inc., and at least 18 supervising governmental and municipal overseeing bodies to monitor the work around the mudflats, the clam beds, the coastal wetlands, the beach and its erosion, the seawall and many other unusual environmental conditions. They all must remain undisturbed while dozens of backhoes and excavators fortify the shoreline and the new structures are being erected upon it.
Working in Meticulous Phases
The work had to be phased over three years not to disturb — equally — the marine life of gulls and gills or the human life of sun worshipers. This was especially tricky because the causeway is the only access to the island of Nahant.
“The project consists of seven phases in order to accommodate the public in the least inconvenient matter. In the first phase, we prepared the causeway for construction, building the temporary lanes, temporary attenuators and barrels for traffic safety,” said Theis Vangsted, project engineer and assistant project manager.
In the second phase, Pihl did all the infrastructure work — telephone, electric and drainage — on the southbound lane toward Nahant. It also performed revetment, pavement, installed granite curb, raised structures and installed guardrail.
In the third phase, it moved to the northbound lane toward Lynn, Mass. and performed all the infrastructure work, paved and raised structures, according to Danté Roberto, project manager and supervisor.
The fourth phase is divided into two parts. The first part of phase 4 consisted of reclaiming the temporary two lanes and some of the parking area, moving water mains and CATV, constructing retaining walls and installing drainage in the parking area. The second part of phase 4 consisted of constructing all drainage in the northbound lane, retaining walls with granite cap, precast/granite curb, chain link fences and constructing the landscaping area between the new causeway and reservation area in the temporary lanes.
Before phase 5 started, the contractor converted the parking area again into two temporary lanes after the beach season ended.
“We were working the northbound lane toward Lynn, where we installed the median guardrail, permanent light poles, relocated primary electric, installed granite curb,” added Vangsted. “In the 6th phase, we worked on both lanes of the causeway, where we installed granite curb, raising the structures and placing top course pavement.”
In the 7th and last phase, which Pihl transitioned to in July 2013, work will be in the reservation area, installing site improvements such as retaining walls, boardwalks, bike racks, trash barrels, planters, flag poles, a water fountain, landscape work, renovating the boat ramp, paving, stripping, and then reconstructing the big barbecue area, Roberto added.
Made for the Job
The machine that Pihl purchased from Lorusso Heavy Equipment specifically for this job is a Liebherr A924C 55,000 lb. (24,948 kg) rubber-tired excavator.
“We were looking for a very multi-faceted machine; a machine that could pick up a 2-ton Jersey barrier and travel with it, without creating any safety issues,” said Roberto. “Throughout this construction project travel lanes are being changed and a lot of Jersey barriers would be handled. We also needed a machine that could travel along a paved road on a job site that extends over 1-1/2 miles without damaging the surface of the asphalt. I had never worked on a project with Liebherr machines in the fleet, but I was aware of the company and their excellent reputation. The Liebherr was the only rubber-tired excavator in its weight class that had this kind of lifting capacity and offered the mobility that we needed.”
The secret to the lifting capacity of the Liebherr is primarily due to two features: the hydraulics and the kinematics of the boom and arm assembly. Liebherr designs and builds its own hydraulic system in house. With multiple operator modes, it is very easy to fine tune the hydraulics to the task at hand, according to the company.
In regards to the boom and arm assembly, the boom is a two-piece boom that is adjustable to accommodate both physical site limitations as well as lifting capabilities. By adjusting the boom, the load can be picked and carried much closer to the machine’s center of gravity. While almost every manufacturer offers a two-piece boom, the way in which the Liebherr is hinged is different from others. Instead of connecting the boom cylinders to the hinge point itself, which is the weak point of the system, the cylinders are connected to their own separate position on the boom, allowing for maximum lifting capabilities.
“In a lot of ways we’ve used this machine like a yard crane. In addition to all of the digging and rock moving we were able to lift a telephone manhole weighing 8.2 tons a total of 22 feet out of a hole. We also had the Liebherr plumbed with a hammer and used it for demo work in early phases of the job. The articulated bucket made the Liebherr an excellent tool for grading,” Roberto said.
“The split boom adds a lot of flexibility that you just don’t have with other machines. You can enter very low clearance areas by dropping the stick lower than is possible with other machines; or you can extend the stick straight out, which is ideal during the grading applications. The Liebherr was priced out very competitively and in spite of being a European designed machine the transition for our operators into the Liebherr was very easy. We purchased the Liebherr from Lorusso Heavy Equipment and they arranged for onsite training. In fact, Lorusso made all aspects of this purchase move along very smoothly. Their service after the sale has been exceptional. Parts availability has been excellent along with their response time to service calls.”
Many Unique Challenges
All work is being overseen by the Department of Conservation and Recreation (DCR), whose mission it is to protect and enhance the commonwealth’s natural resources.
With the causeway being the one access to Nahant, the challenge to Pihl Inc. was to keep two lanes open in, and two lanes out, at all times.
“We had to build a temporary two-lane roadway in order to accommodate the commuters during construction phasing,” said Vangsted.
Beach walkways and the parking area are used predominately in summer season and are open from dusk to dawn.
“The challenge is to perform the renovation work in the area while keeping the beach safe and open to the general public,” said Roberto. “[Another] challenge is to avoid disturbing the dune grass and natural resources with wildlife protection. Mudflats are a conservation preserve. The challenge there was to construct riprap revetment with minimal disturbance to both aquatic life and/or sea plants.”
Time and tides were carefully gauged.
“The biggest challenge [so far] has been traffic safety during the summer season. We have been working right next to the public during most of the project,” said Vangsted. “In the summer season, there are only a few feet between us and the public and we have to cross the same areas. Safety is our main priority and we have been fortunate to avoid any accidents involving the public.”
Constructing the revetment was performed during low tide shifts and took approximately 11 months to complete, Roberto added.
In order to protect the clam beds, per the Army Corps of Engineers permit, a 15-ft. (4.6 m) access from the riprap toe was established. Meetings were held with the marine subcontractor prior to startup to enforce these regulations. During construction, the work was monitored by Pihl Inc., DCR, Nahant Conservation Commission and the Army Corps of Engineers.
Seaweed, eel grass and shell life along the beach is protected by the OOC (Order Of Conditions) in the contract. Pihl Inc. is performing all work within those areas. Meetings were held with DCR prior to startup to enforce the regulations.
“DCR’s resident engineer is informed on a daily basis and our approach and means of methods are discussed before working in the areas,” said Roberto. “All waterfront projects are extremely sensitive and most restrictive for permitting.”
Humans Just as Important
“The D.C.R. has provided us with construction plans that improve the traffic controls, vehicular and pedestrian safety,” said Vangsted. “All the items of the road will be in accordance [with] A.D.A. and federal standards. The new longitudinal pitch in the causeway will improve the previous flooding problems in the causeway, which only had lateral pitch. The vehicular and pedestrian lanes will be clearly marked. Boardwalks to the beach will provide improved pedestrian and handicap access.”
Reservation identity also will be improved.
“The area will be clearly identified by the landscape area, fence and retaining wall between the causeway and reservation. The landscape areas, parking, benches, bike racks and all other non-vehicular improvements will identify the reservation area as a recreational spot for the general public,” added Roberto.
It also will enhance reservation aesthetics.
“The DCR made it a high priority to design an aesthetically-pleasing project. They focused on using natural blending materials for construction of all structures,” said Roberto. “All natural resources will be fenced [with a rope fence] in order to protect them.”
The North Shore of Massachusetts has faced powerful winds of countless nor’easters, hurricanes and ocean storms for untold centuries. Nahant Beach is a peninsula right in the heart of these storms as it juts into the ocean, northeast of Boston.
The beach is eroding but Pihl Inc. has literally stemmed the tide.
“The southbound side of the causeway erodes naturally due to tidal action. In order to prevent further erosion, geotextile fabric was installed under the revetment,” said the two project managers. “The geotextile fabric is pervious to water and retains the fines from migrating away after each tidal influx. The revetment, which is made of armor stone, up to 8 tons, dissipates the wave energy and prevents further erosion.”
In various reconstructions of walls, buildings and the parking lot, the following materials will be used:
• Riprap, boulders and crushed stone — approximately 45,000 tons (40,823 t)
• Sand/soil/millings — approximately 90,000 tons (81,646 t)
• Concrete — approximately 5,000 cu. yds. (3,823 cu m)
• Asphalt — approximately 55,000 tons (49,895 t)
Beside the rebar steel in concrete structures, steel also will be used in fences, guardrail posts, signposts and miscellaneous reservation items (bike racks, benches etc.).
The guardrail used is made of timber, except the posts; granite has been used as curb, wall cap, pavers and medallions in order to complement the natural theme. No seashells have been used other than its decorative design.
“The parking lot will be completely renovated with new asphalt, striping and walls. It will have landscape boulder gardens and handicap friendly access to the beach,” said Vangsted. There will be some 900 parking spaces when completed.
The various elements of construction include:
• Marine: revetment and boat ramp at harborside; access ramps at oceanside
• Concrete work: retaining walls, median barrier and spall/crack repairs
• Asphalt work: paving roadway, sidewalks and parking areas
• Electric work: conduit, wire and light poles
• Utilities work: telephone, electric, drainage, water mains and CATV
• Masonry work: granite wall cap, medallion, pavers, granite bollards and site improvement
• Parks work: benches, trash receptacles, bike racks, flag poles, water fountains, etc.
• Traffic controls: signage, markings and message boards
“We want the public to appreciate the safety measures, quality of work and patience Pihl took to improve this location for them,” said the managers. “The project is a complete renovation of the entire area and nearly all utilities. The project will eliminate all flooding and erosion problems that the area has been dealing with for the last decades.”
The work has been extended 12 months due to unforeseen conditions, improvements of design and extras. Despite all the changes, the project is still on budget and its revised schedule on target.
DCR’s investment in the community goes beyond the $20 million causeway project. The Ward Bathhouse on site was rebuilt ($600,000), rail painting was performed on Lynn Shore Drive ($200,000) and a “Halfway House” was reconstructed for $1.2 million. These are all separate Nahant Beach contracts, beyond the work by Pihl Inc.
And even when Nahant Beach has been restored, the work won’t end for Pihl.
“Pihl Inc. is proactive in ’beneficial reuse’ of onsite demolished materials such as concrete, asphalt and soils,” said Vangsted and Roberto. “Most are processed here onsite to be reused as gravel base, structural fill and landscape bedding.”
Away from the beaches, of course.
For more information, visit www.pihl-inc.us.