Crew Fights “Pier Pressure” To Meet
Blasting, Coating Challenges

By Ben Grier with Jen Kramer
    

A recent blasting and coating project for the San Clemente Pier in San Clemente, California was no simple walk on the dock of the bay. It offered significant challenges that dictated the design of a contained environment underneath the pier dock and a precisely controlled environment. Thanks in part to a sophisticated climate control system from Munters, the coatings application proceeded as planned and the pier re-opened on schedule.

The 1,296-foot San Clemente Pier offers sweeping Pacific Ocean panoramas, fishing, dining and views of surfing competitions and beach activities.

City officials determined the pier, last renovated in 2005, needed a major makeover including timber decking replacement, new guard rails and stringers, steel pile cap maintenance, repairs to protective coating on steel piling, beams and pile caps, installation of an active corrosion protection system, new light fixtures and poles, and electrical upgrades.



Corrosion of the steel pylons and metal support columns underneath the pier was the result of years of exposure to saltwater and humidity. Houston-based The Brock Group, a contractor specializing in such maintenance activities and work, was hired to oversee the blasting and coating portion of the project.

Brock decided to divide the work into four pier sections of approximately 50,000 cubic feet each. After sandblasting the metal, a three-coat painting system consisting of a zinc coating, epoxy primer and polyurethane finish would provide corrosion control and prevention.

The project began in January 2010 and required completion by that Memorial Day weekend so the refurbished pier could be unveiled at the start of the busy summer season.


Project Offers Challenges

The blasting and coating needed to take place underneath the pier, which created a unique challenge for the project because it required development of a complex scaffolding containment area to allow the crew to access that area.

“This was the first time I oversaw a pier project in which we conducted the work underneath the metal pylons that support the structure,” says Tim Johnson, project superintendent with Brock Services, Ltd., a division of The Brock Group.

Johnson hired Paramount Scaffold to design and build a suspended scaffold deck to hang underneath and be supported by the pier. Since they were working over open water, another challenge was ensuring a contained working space to prevent materials from polluting the ocean. “During blasting projects, debris grit is displaced and applied coatings can become airborne,” explains Johnson. “We had to be very careful that we did not contaminate the ocean below us, so such debris was carefully ‘managed’ with the use of a shrink-wrap plastic containment system. We also used a Vector Dust Collector and a Hurricane vacuum.”

Another major concern was moisture levels from the ocean and how this moisture would delay and negatively impact the curing of coating materials. “Condensation and temperature extremes lead to flash rusting, inter-coat adhesion problems and curing issues, and create expensive delays, rework and warranty repair costs that can affect the overall service life of the project,” states Johnson.

Dehumidification Speeds Completion

Based on these conditions and concerns, completing the blast and coat operation in a timely manner required the use of a temporary climate control system to create an environment conducive to curing the coating materials. The contractor specified that the relative humidity in each containment area remain at or below 30 percent.

Johnson, who in the past utilized the Moisture Control Services (MCS) division of Munters in other temporary humidity control applications, called Kerry Saulet, account manager with Munters, to design a system to control moisture and temperature during the blasting and coating process.

“Desiccant dehumidification (DH) technology is used in the coatings industry as a method to help control flash rusting, enabling the applicator to provide a superior finish even in the harshest environments,” says Saulet.  “This particular project required a unit to maintain conditions as each section of the pier was sandblasted so all of the coatings could be applied in a period of days.” Saulet selected a Munters DHi35 PowerPurge unit to provide humidity control for the project.

The DH unit was placed on top of the pier over the blasting and coating area and powered by a temporary portable electric power generator. A flexible duct was tunneled into the containment to vent conditioned air into the space. The space was contained with a heavy plastic shrink-wrap to maintain indoor conditions.

As work began, Johnson utilized an inspection company, Corrpro, to document each project phase and record humidity levels in the air, the temperature within the containment area and the type of equipment used. “We took manual readings of the relative humidity on a daily basis to make sure conditions were maintained,” says Johnson.

When working on the piles, pile caps, steel beams, and pile pipe collars, the Brock crew used a Binks conventional agitating spray pot to spray-apply a three-coat system of Carbozinc 859 VOC at 3-5 mil DFT followed by 4-6 mils DFT of Carboguard 890 VOC using a Graco Xtreme 56:1 airless sprayer, topped by 3-5 mils DFT of Carbothane 133 MC, also spray-applied with a Graco Xtreme 56:1 airless sprayer.

The crew used a brush and roller to apply Carboline Phenoline 309 at 20-30 mils DFT onto the steel beams and piles at the area where the pier meets the beach. Any interface areas were coated with Carbowrap Tape series (a mix of paste, mastic, and Marine tape).

The wooden handrails were primed with Carboacrylic 120 at 1-2 mils DFT and finish coated with Carboacrylic 3359 at 2-3 mils DFT.

Major Winter Storm Wreaks Havoc

The project faced one last major hurdle when a major winter storm hit San Clemente and destroyed part of the scaffolding on the pier. “We had to shut the job down on an emergency basis for over a month due to the storm,” Johnson recounts. “We evacuated all the equipment including the dehumidifiers and cranes.”

Due to lost scaffolding and other materials, Johnson was forced to hire divers to retrieve materials that fell into the water. The setback initially pushed back the timeline, but workers’ shifts were extended to make up time.

“From the beginning of the project, we held weekly progress meetings with the City, the General Contractor and all subs. San Clemente lifeguards also attended the meetings as needed in order to address any events that might take place during the job,” Johnson explains. Fortunately, the only thing that had to be retrieved was the equipment that was swept away during the storm.

The crew was very safety conscious. “When working over the water with no shrink-wrap in place, a life vest and harness were required. When sandblasting, we wore positive air-fed blasting hoods, coveralls, leather gloves, and steel-toed boots. When painting we wore Tyvek coveralls, full-face respirators, cotton gloves, and hard hats, eye and ear protection.”

Work continued a month after the storm, and the project was completed just before Memorial Day as scheduled. “Without the Munters MCS unit to control the climate in the containment area, and the guidance of the Munters team, we never would have met our deadline,” Johnson says.
 

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