Terra-Petra’s Blindside Waterproofing Project featured in Waterproof! Magazine

Terra-Petra Building Waterproofing Division Project Featured on the Cover of Waterproof Magazine, Fall 2018



Blindside waterproofing systems are among the most difficult to design and install.  These waterproofing and drainage systems are placed before the structural walls are poured, which means they must be installed over a soil retention system rather than concrete or masonry.  That retention system—whether it be lagging beams, sheet pilings, shotcrete, or compacted native soils—is typically rough, uneven, and subsequently requires extensive detailing.

Additionally, blindside applications are usually part of massive projects that extend far below a water table where, in some cases, hydrostatic pressure can be extreme. Here, the workmanship must be flawless, as once the structural wall is in place, it is extremely difficult to repair any leaks that develop.

While blindside waterproofing is a considerably more complex below-grade solution, sometimes it’s the easiest—or only—way to get the job done: Applications of this waterproofing methodology can be found in bored tunnels and deep foundations where over-excavation isn’t possible, for example. Blindside techniques are also optimal when property lines and/or nearby structures limit excavation and access, such as “zero lot line” foundation walls.

This was the case at 1840 N. Highland Ave., a luxury multifamily complex constructed in the heart of Hollywood, California, steps away from the world-famous Hollywood Bowl and Hollywood Boulevard.  Typical of many projects in high-density, built-up areas, the 118-unit complex is sited on a tight lot, and extends three stories below grade to create space for mechanical systems and tenant parking; an ideal scenario for blindside waterproofing techniques.

As the schedule moved forward, it transpired that there were several unique complexities, which made the project even more challenging.

The entire lot was excavated to more than 30 feet below grade, with soldier piles, wood lagging, and rock bolts used to keep the surrounding soil in place.

“There were some real twists to the project, including two fault lines under the cantilever of the building and the water table, which sat at different levels,” says Josh Heidt, with Terra-Petra, the company contracted to provide waterproofing consulting services.

Terra-Petra brought in Epro Services, a Kansas-based waterproofing company with a long history of success on blindside jobs in the state, to provide a solution. Heidt says, “Epro has the kind of case history we were looking for from a manufacturer on a multi-faceted project like this.”

Construction began with a major earthmoving project.  The entire 8,144-square-foot lot was excavated to more than 30 feet below grade.  Soldier piles and wood lagging were used as a retention system, augmented by tiebacks and soil nails. On one wall, massive tubular steel rakers—more than three feet in diameter—were used to ensure that the foundation of the adjacent seven-story building stayed in place.

To ensure optimal waterproofing, the system had to seal tight despite the irregular substrate and needed to be durable, too. The structural walls would be placed with shotcrete, which would be applied directly to the membrane without a protection course.

The underslab barrier extends up the wall two feet higher than the water table. The mat of reinforcing steel will be encapsulated in the four-foot-thick foundation

The architect worked closely with the geotechnical consultant and the waterproofing supplier to ensure the specified system would perform as designed.  Architect Ronald Rosell, representing the project architect Arquitectonica, says “Epro helped us and the geotechnical consultant work through the issue regarding the north face of the building where the fault line divided the water table.”  He continues, “The fault acted like a subterranean waterfall, and Epro gave us recommendations for how best to prevent that hydrostatic pressure and constant flow of water from impacting the structure.”

The general contractor, Frymer Construction, was also brought into these discussions to ensure the design would be buildable.  “We collaborated with Terra-Petra regarding the usual qualifications, review of transitions, and fastening and drainage considerations,” says David Frymer, company president.

The bottom of the excavation was about 10 feet below the water table, so crews poured a “mud slab,” then installed the underslab waterproofing system:  Epro’s E.Protect+ Underslab, which features built-in layers of redundancy.  It’s achieved by combining different types of waterproofing materials to leverage the positive attributes of each, a technique they call “Redundant Field-Installed Composite Design.”

Tubular steel rakers more than three feet in diameter provide support for the lagging and simplify the detailing.

In this particular application, E.Protect+ Underslab was comprised of a layer of 16-mil HDPE thermoplastic membrane with heat-welded seams, over which the team spray-applied a 100-mil layer of polymer modified asphaltic membrane.  Finally, this was topped with an HDPE-reinforced bentonite sheet which will expand to seal any leaks that may develop in the future.

This triple system was installed across the slab and up the walls two feet higher than the historic high water table level.   Then the structural slab was poured, four feet thick with a double mat of reinforcing steel running 12 inches on center in both directions.

Above the water table, Arquitec-tonica specified E.Proformance Shoring, a blindside waterproofing system used for non-hydrostatic conditions. It’s comprised of a 30-mil HDPE dimpled drain mat installed against the lagging, which was then sprayed with a 60-mil layer of the same asphaltic membrane used in the underslab waterproofing.

The spray-applied coating is formulated so that the heat generated by curing concrete will chemically bond the product directly to the structural wall. The dimples in the drain mat also help prevent delamination between the membrane and the concrete.

E.Proformance was used all the way up to grade level, where it was transitioned to a hot rubber horizontal waterproofing system that was used to seal beneath the planters and the above-grade stucco wall system.

In total, the project used 70,000 sq. ft. of waterproofing.

EPS “geofoam,” reduces the effect of seismic movements on the building’s structure and create a smoother substrate for the waterproofing.

Experts say the key to quality in any blindside application is the ability to detail around the soil retention system.  This project used an ingenious solution to resolve that dilemma: A two-foot-thick layer of EPS “geofoam,” installed between the retaining wall and the shotcrete structural wall.

Provided by Insulfoam, this rigid insulation arrived in giant blocks and was installed between the retaining wall and the dimple membrane.  The geofoam will reduce the effect of seismic movements on the building’s structure and creates a smoother substrate for the waterproofing.

Crews fastened the geofoam directly to the lagging. Then the dimple drain sheet was fastened over the foam, with the waterproofing layer spray-applied to the dimple sheet. The same spray-applied product was also used to detail around the many pipe penetrations, the pits for elevators, and utilities.

“My experience with Epro has been outstanding,” says Mostafa Sobhi, president of BM Builders and the certified Epro applicator responsible for the installation. “Their quick turnaround in answering any concerns and providing details due to changing field conditions has been a huge factor on how jobs like this can be successful, while also maintaining schedules.”

Heidt reports that Epro representatives were “on the site a great deal of the time” to ensure the workmanship was flawless. Despite the high level of complexity and the presence of hydrostatic conditions, working closely with the project team enabled Epro to provide a 15-year no-dollar-limit warranty to the developer.

The project at 1840 N. Highland Ave. is scheduled for completion in 2019.

The 1840 N. Highland Ave. apartments are on schedule to be completed in 2019.  The development shows that despite the difficulties blindside work presents, with the right materials and know-how, contractors can get excellent results.

The Terra-Petra Waterproofing Division team will be exhibiting at the RCI Trade Show Exhibit in Houston

Terra-Petra Waterproofing Division Exhibits at RCI International Convention & Trade Show

The Terra-Petra Waterproofing Division team exhibited at the RCI International Convention & Trade Show at Houston’s George R. Brown Convention Center on March 24-27, 2018.

Our group of professionals provided information and further insight on our BUILDING ENVELOPE CONSULTING * ELECTRONIC LEAK DETECTION * CERTIFIED AIR & WATER TESTING  * INSPECTION & MONITORING services.


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The annual RCI, Inc. International Trade Show offers attendees the chance to meet and learn from representatives from over 130 manufacturers of roofing, waterproofing, and exterior wall products. 



Terra-Petra Waterproofing Team meets for continuous training with WPL Group distributors of Tyvek systems

Terra-Petra waterproofing team got together, October 18, 2017, for more continuous training by industry experts.  This latest training session was performed by the technical experts at WPL Group, distributors of Tyvek systems. Terra-Petra is continually gaining knowledge in all aspects of building envelop waterproofing and consulting, and becoming certified with many different systems and products.




Terra-Petra Company Christmas Party 2016: Another Memory Maker!

Terra-Petra's CEO, Kevin Buchanan and VP/General Manager, Justin Conaway another memorable holiday party for the Terra-Petra team and family last Saturday night! The group gathered at Downtown Los Angeles' favorite Maso Malo (one of Kevn and Justin's favorite gathering places for the group over the years). 

"I was happy to see all of the people that have helped make Terra-Petra great in 2016 having so much fun. This party was a direct reflection of the growth and success that we have had all year long.  I would have to say that this was not only our biggest, but probably the best party we have had so far. I'm happy we can continue this tradition every year. It just gets bigger and better everytime." – Justin Conaway 

The Terra-Petra Founding Fathers

The Terra-Petra Founding Father Hugh Avery with Terra-Petra original crew, John Conaway, Richard McClanahan and David Lucero.

The Terra-Petra LA Office Crew.

The Terra-Petra LA Office CAD Crew.

CEO Kevin Buchanan shows off Terra-Petra bucks for the party raffle!

CEO Kevin Buchanan shows off Terra-Petra bucks for the party raffle!

CEO Kevin Buchanan with VP/GM Justin Conaway.

In Kein Buchanan We Trust!

In Kein Buchanan We Trust!

Terra-Petra Inspection Team

Terra-Petra Inspection Team with fearless leader Dan Valdez.

CEO Kevin Buchanan with the Terra-Petra Inspection Crew.

CEO Kevin Buchanan with the Terra-Petra Inspection Crew.

Terra-Petra Inspectors

Terra-Petra Management at their finest.

Terra-Petra VP/GM Justin Conaway with Inspector Supervisor, Daniel Valdez.

VP/GM Justin Conaway with Inspector Supervisor, Daniel Valdez.

The Terra-Petra LA Office Crew.

The Terra-Petra LA Office CAD Crew.

Party goods!

Maso Malo Buffet for the Terra-Petra party goers.

Maso Malo Buffet for the Terra-Petra party goers.

Terra-Petra supports the City of Hope Construction Industries Alliance Spirit of Life Gala

City of Hope Construction Industries Alliance Spirit of Life GalaTerra-Petra has proudly joined the efforts of MVE + Partners in supporting the City of Hope Construction Industries Alliance Spirit of Life Gala which will be held in Orange County, California this fall. 

The City of Hope National Medical Center is a private, not-for-profit clinical research center hospital and graduate medical school that is dedicated to making a difference in the lives of people with diabetes, cancer and other serious illnesses.

The City of Hope mission is accomplished by providing healthcare, conducting innovative research and offering vital education programs focused on eliminating these diseases.Through making a small contribution, Terra-Petra stands together with other construction industry professionals in the spirit of life to fight against cancer and search for a cure.

For more information regarding sponsorship, tickets or other event details (venue and date to be announced), visit: http://www.cityofhope.org/spirit-of-life

Terra-Petra Welcomes San Francisco Bay Area Account Executive, Mark Wagner

Terra-Petra recently welcomed account executive, Mark Wagner, to the company’s San Francisco office. He will handle the management of the increased environmental engineering project workload coming out of a developing San Francisco Bay Area market. Mark’s degree in engineering and prior experience working for a Northern California firm that handles contaminated soil and water remediation makes him the perfect person to serve as Bay Area account executive for Terra-Petra.  

Mark received his engineering degree from Messiah College in Mechanicsburg Pennsylvania—where is also held a position as student project manager for the school’s Biodiesel Project. In this role, he conducted research for possible uses of glycerin from the biodiesel production process and led a team of peers to focus on engineering design project management. While attending Messiah, he also spent time as an intern for HCJB Global in Ecuador, gaining experience in topographical map development as well as direct project oversight and successfully led the development of a spring preserve for a community of 85 residents to access clean water in the Amazon. 

Mark gained his most recent project management experience serving as project coordinator for Innovative Construction Solutions. At Innovative, he had the opportunity to gain insight into environmental remediation working with multiple project managers, and tracking progress on multiple projects throughout the Bay Area. Mark Wagner is a true pioneer in the environmental engineering industry and the perfect fit for Terra-Petra’s expansion into the Bay Area.

Terra-Petra at ICSC RECon 2015 – Las Vegas – May 17-20

#recon15Environmental Engineering firm, Terra-Petra, will once again have a booth in the “Green Zone”  booth N1665 on the Exhibition Floor at ICSC RECon 2015 in Las Vegas (May 17-20). For more information visit: https://lnkd.in/bDrCKKS.

Contact Terra-Petra VP/GM, Justin Conaway,
to request/arrange a meeting day/time while at the convention.

Terra-Petra’s GM/VP Justin Conaway to speak at the Colorado Environmental Management Society March 10

JustinConawayVPGM Terra-Petra GM/VPCEMS March Luncheon – Engineering Control Trends in Vapor Intrusion Mitigation – March 10

Speaker: Justin Conaway, Vice President |General Manager and Patrick Guan, Regional Manager, Terra-Petra Environmental Engineering.

Tuesday, March 10, 11:30am – 1:00pm.  There will be no CLE for this presentation.

In recent years the implementation of vapor intrusion mitigation systems has become more common for ground-up development. There are many different forces and factors that are influencing this rise in popularity. There are also numerous engineering controls available to protect a given building from vapor intrusion. This presentation discusses the Vapor Intrusion Mitigation Engineering Control Trends that are being specified and installed today on new construction projects. The benefits of these systems will be outlined and we will identify how various stakeholders have influenced the current trend.

Justin Conaway, VP/GM of Terra-Petra has been with the company since 2004. In this time he has developed a unique knowledge of the vapor intrusion industry in that he has been involved with nearly every aspect of the vapor intrusion cycle from site characterization through installation.

Mr. Conaway has a wealth of experience and competencies, including: Construction Quality Assurance Inspection, Mitigation System Design, Permitting, Document Submittal and Negotiations with Governing Agencies, Risk Management Decision Making Process with Developers, Contract Negotiation, Installation Costing, On-Going Operation and Maintenance Monitoring and Reporting, and Research and Development to launch innovative vapor intrusion products.

Patrick Guan, Regional Manager for Terra-Petra has been with the company since 2012. In this time, he applied his vast experience in sales/marketing, strategic planning, operational management, and superior customer service skills that he developed over the past 17 years working for fortune 500 companies to help drive the ambitious expansion goals of Terra-Petra from a regional success story to a thriving successful nationwide operation. He has done this by executing a clear and concise marketing campaign that presented a positive compelling brand identity for the company. He helped increased the company’s market share throughout the country by emphasizing Terra-Petra’s expertise, and superior value driven customer service that has made it so successful in the West Coast region.

LOCATION: The EPA Conference Center located on the 2nd floor of the EPA Region 8 Headquarters building at 1595 Wynkoop Street in Denver, Colorado. 

To register, please visit this link

Terra-Petra Announces New Office and New Presence in New York City and on the East Coast


For Immediate Release
Contact: Laurie Pehar Borsh
Laurie Pehar Borsh PR
800-915-2151 x706

Los Angeles, CA (PRWEB) December, 02 2014–Environmental Engineering firm Terra-Petra recently announced that it has continued to formalize its national expansion with the opening of its newest office in New York City. The environmental engineering firm, specializing in contaminated soil and groundwater conditions, has opened its newest office in One Penn Plaza, on the 36th Floor.

Terra-Petra’s expertise starts with soil gas characterization, remediation, and in the design and inspection of gas mitigation systems for buildings of all types – including commercial, multiple family, single family, industrial, institutional and retail. We are methane experts and methane gas specialists. With the NYC office officially in place, the firm has already taken projects in the surrounding areas.

“Our expansion out east allows for the opportunity to offer coast to coast coverage of Terra-Petra’s services. We have found that many of our clients that are based on the east coast have projects going on in the west coast, and visa-versa,” said Kevin Buchanan, CEO of Terra-Petra. “It’s a very unique situation with many of our clients, and for us to have a presence in New York simply strengthens our relationships with our larger clients. As we suspected, our clients on the east coast are faced with very similar environmental constraints that exist on the west coast.”

“Our national reach allows us to jump in with our expertise without missing a beat, when called on to perform our services,” Justin Conaway, Terra-Petra VP/General Manager added. “Terra-Petra is also looking at the possibility of opening up an office in the Midwest next year, in order to give us even better national coverage of our services. More to come on that as we move into 2015.”

Terra-Petra was founded, and is committed towards the purpose of creating a safe environment for building and structure occupants, free of toxic vapors and volatile organic compounds. Terra-Petra utilizes current expertise and state-of-the-art technology to engineer environmental solutions in concert with local and federal agencies to assure compliance with all code and regulations, and ultimately protecting people from unsafe building conditions.

More about Terra-Petra 
With its strong presence in the environmental engineering industry for over 20 years, Terra-Petra has many successful projects to lean on. The company started its operations focusing on the Los Angeles market to address the local "methane concerns" that quickly became a big issue in the early 1980s. Terra-Petra’s in-house experts were also a big part of the original team that developed the local Los Angeles Methane Code which has been mirrored by many other cities over the years. With more than 80 years of collective experience in the environmental and soil gas mitigation fields along with a staff of Construction Managers, Civil Engineers, Registered Environmental Assessors, and Registered Geologist/Certified Engineering Geologists, Terra-Petra has the ability to find compromise solutions for any environmental concern that may arise. .

New York Office:One Penn Plaza; 36th Fl, New York, NY. 10019 – (212) 786-7456 
Los Angeles Office: 700 S. Flower St; #2580, Los Angeles, Ca. 90017 – (213) 458-0494                         
San Francisco Office: One Sansome Street; Ste #3500, San Francisco, Ca. 94104 – (415) 590-4890

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