09_4_Fall

Vol. 12 Issue 4 PRACTICAL AND ENTERTAINING SINCE 1997 Autumn 2009

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THE POCKET

See PROPERTY - Continued on page 2

By Steve Flaten, AIA, LEED AP, and Ron Reigle, AIA

It’s nearly impossible to turn on the radio, watch TV or read a newspaper without being bombarded by news about the economy and its impact on the construction and real estate industries. Foreclosures, bankruptcies and financing concerns are placing many projects on indefinite hold. As we noticed with previous economic downturns, tough times often result in a high occurrence of deferred building maintenance. Add staff cutbacks and capital spending freezes to the mix, and a recipe for unused and distressed properties develops.

While the market may be forcing some developers and building owners to leave projects idle, it is important to understand how making certain considerations can

impact the future usefulness of a building. Braun Intertec often conducts property condition assessments (PCAs) based upon ASTM Standards for clients and their financial organizations. Typically, on-site reviews include observation of the physical condition of a structure for any warning signs of structural damage, settlement, or deterioration of building components. We often observe that if properties are repaired during tough economic times, repairs may be done at the lowest possible cost by unqualified contractors. Resulting poor workmanship and improper use of materials may create additional problems with these properties.

Tips professionals can use to evaluate the physical condition of suspect buildings include:

Avoiding stress with distressed properties

Roofing Conditions Deterioration of roofing membranes is the primary cause of building envelope problems. If neglected, roof leaks can cause substantial structural and material damage. Roof membrane failure can impact occupancy and tenant retention and reduces the perceived quality of the property. Roof membranes are constantly tested by the elements, including sun exposure, weathering and storm damage. A common approach to roof repairs is to patch the membrane for as long as feasible to hold off on reroofing for as long as possible. Single membrane roofs of ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC), or thermoplastics normally have a useful life of 10 to 15 years. It is not unusual to reach 20 years; however, extending the life of a single-ply membrane requires regular maintenance and repairs that increase as the roof ages.

Built-up asphalt roofs have a longer life cycle than single-ply membrane roofs because they are more resistant to sun exposure,

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Steve Flaten, AIALEED AP

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Ron Reigle, AIA

Issues to consider when dealing with distressed properties include the potential for roof disrepair, leaky windows, the affects of cold weather, and water intrusion.

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PROPERTY - Continued from page 1

weathering and storm damage, and therefore require less maintenance over the life of the system. Built-up roofing typically has a higher initial installed cost, but the longer life cycle of the system typically results in a lower annual cost.

Water Intrusion New buildings are demonstrating more susceptibility to water intrusion and condensation issues that can lead to material damage and fungal growth in wall cavities due to lack of redundancy. Resulting cleaning costs and material replacement are expensive and in some instances may require displacement of tenants. The use of caulking and sealants is often the only means of keeping water out of the exterior envelope of a building. Improperly placed caulk can crack, tear, or fall out, leaving the interior of the building susceptible to water infiltration. Caulk failures typically occur in control joints, window perimeters, metal panel systems, exterior insulation finishing systems (EIFS) and precast panels. Chalking, surface crazing, loss of adhesion and tears indicate a need for replacement. Holding off on repairs can quickly lead to a total system failure in susceptible systems like EIFS.

Leaky Windows Leaks in windows, storefronts and curtain walls occur for many reasons, including product design issues, poor installation, or total reliance on sealants to provide a weathertight seal. Look for the tell-tale sign of sealants being applied over glazing gaskets on the exterior of a window. This “wet seal” is a warning sign as it often indicates recurring leaks in the system that may have had many attempts at correction. A wet seal is often applied to avoid investing in a complete repair or replacement of glazing gaskets. This fix serves as one way to cover a problem rather than repair the source and will likely continue to produce nuisance leaks and require frequent re-caulking.

Cold Weather Damages We also see a number of buildings put into “cold storage” when a lack of occupancy results in turning down the heat to just above freezing or shutting it off entirely. Without proper draining of hot water heating systems, toilets, domestic water piping, boilers, and heating, ventilating and air conditioning (HVAC) units, there can be a lot of hidden damage. Lack of heat in a building can cause hidden damage in the walls and other components due to condensation and freeze/thaw. Masonry block walls, especially rock face or split face, may absorb rain and condensation that can freeze in the wall cavity or in the face of the masonry, causing spalling of the masonry surface. In older buildings it was not unusual to fill masonry cores with vermiculite insulation. In extreme

cases, water in the wall saturates the vermiculite, which in turn causes further structural damage to the wall when frozen. Regular maintenance may have avoided very costly repairs. Vermiculite is a potentially hazardous material that can potentially contain asbestos. It should be handled accordingly.

Similar to the inspection process for buying a car after a flood, due diligence is also key when purchasing distressed buildings. For protection, start by looking for some of the above warning signs. Ask for records and receipts of repairs. Talk with maintenance staff, if available, and contractors who performed the work. Review their recommendations and how they were received. In general, additional due diligence is advisable to evaluate the true condition of distressed properties.

Prospective buyers are strongly encouraged to retain professionals to conduct due diligence investigations before making final commitments on distressed properties. Know what you are walking into before you make the purchase. Damage due to poor maintenance is not always visible to the untrained eye.

Instead of repairing the window, sealant was applied to the glass intersection.

This brick has a partial tuckpoint allowing water intrusion through wide open joints.

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This Harvey Dunn painting of a resident in a retirement home for Vaudeville actors was x-rayed at Braun Intertec. The portrait of the actor was painted on top of another image, which was revealed via x-ray because of the lead content in the materials that Dunn used.

By Greg Ebeling

Editor’s note: Greg Ebeling, a technician in the Braun Intertec nondestructive examination (NDE) group, along with a paintings conservator from the Midwest Art Conservation Center, carefully examined this painting to determine appropriate settings for x-radiography. Ebeling has examined pottery and sculptures using NDE methods to help

X-ray reveals what was behind the face

determine their authenticity and quality of workmanship.

Harvey Dunn was an American illustrator from South Dakota whose work appeared in The Saturday Evening Post, Harper’s, and a number of other publications during the early part of the 20th century. Like many artists at that time, Dunn re-used old canvases and created new paintings on top of old images.

In 2008, the Midwest Art Conservation Center, on behalf of the South Dakota Art Museum at South Dakota State University in Brookings, brought a Dunn painting to Braun Intertec to be x-rayed. Curators suspected that the painting, which featured a Vaudeville actor in a retirement home, may have been painted on top of another image. They hoped an x-ray might reveal an image below the portrait of the actor, as paint from that period most likely would have contained lead, detectable by x-ray. In the testing industry, x-ray tubes are often used to examine welds, castings and other objects.

With this piece, the entire painting was x-rayed in one exposure with overlapping films placed under the painting. Using very low kilovolt and milliamp settings, as well as a long x-ray tube-to-film distance, the film was allowed to expose for about 30 minutes. The results were impressive and the film picked up an image of men on a boat. The Midwest Art Conservation Center was then able to digitize the x-ray films and “stitch” them together to make a seamless composite, as the paintings are often large and each piece of film only covers a portion of a painting. The South Dakota Art Museum then began working with volunteers to identify the image.

Because the paint that Dunn used contained a high amount of lead, it was possible to clearly see the image of the original painting. That was pretty amazing. So often, the nondestructive examination x-ray services that Braun Intertec provides relate to welding or piping discontinuities, so being able to use this technology to learn more about art was special.

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Greg Ebeling

Braun Intertec opens two new offices:

Duluth and Milwaukee We are pleased to announce the opening of our new Milwaukee and Duluth offices. The Milwaukee location will be managed by Matt Poehlman, PE, who recently joined Braun Intertec as a project engineer. His office is located at 304 Travis Lane, Suite 21, Waukesha, WI 53189. Matt can be contacted at 262.513.2995, or [email protected].

Earlier this year Braun Intertec opened a regional office in Duluth, MN, to serve the region’s growing industries. Paul Burley, PE, PG, will oversee the Duluth office as a principal engineer and scientist. Joe Butler, PE, is from the Duluth area and serves as a project engineer for the office. The Duluth office is located at 4511 West First Street, Suite 4, Duluth, MN 55807. You can reach Paul or Joe by calling 218.624.4967.

Paul Burley, PE, PGpburley@

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Joe Butler, PEjbutler@

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See CHERRY - Continued on page 5

By Tim Williams

Editor’s note: Tim Williams, a National Association of Corrosion Engineers (NACE)-certified Level 3 coatings inspector at Braun Intertec, designed the specifications and oversaw the recoating of the “Spoonbrige and Cherry” sculpture, which is displayed in Minneapolis. This article was recently featured in Materials Performance magazine.

For more than two decades, the “Spoonbridge and Cherry” sculpture in the Minneapolis Sculpture Garden near the Walker Art Center has been a symbol of the Twin Cities. In February, after more than 20 years of being perched atop a giant spoon, the 1,200 pound metal cherry was removed and taken to a local paint facility for a facelift.

Walker Art Center representatives who are in charge of the sculpture by Claes Oldenburg and Coosje van Bruggen had noticed some surface irregularities on the cherry and were concerned about the condition of its coatings. A failure analysis was performed by closely inspecting the cherry from a lift while it was still attached to the spoon. While the cherry had been repainted three previous times throughout the years, it was noted that the paint was fading, exhibiting slight discolorations, along with some microscopic surface cracking. These conditions were most likely brought on by more than 20 years of extreme conditions, such as temperature variations, ultraviolet (UV) rays from the sun, and being exposed to water as the sculpture is part of a water feature. Because of that perfect storm for paint problems, and after being displayed for more than two decades, it was really a choice between refinishing the entire cherry or repairing different areas of the sculpture year after year.

After examining multiple options, Walker Art Center representatives decided to refinish the sculpture’s “cherry.” In February, they removed the cherry part of the sculpture and sent it by flatbed truck to Industrial Painting Specialists (IPS), a local coatings facility in Hugo, MN. Specifications were designed for how the cherry should be coated after taking several issues into consideration. Rob Roy, one of my NACE instructors who I’ve stayed in contact with throughout the years, was able to provide me with background information about the sculpture. Roy had consulted on the sculpture as it was being built in Connecticut. Networking through NACE helps professionals maintain the standards that are taught to them when they get their certification.

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Tim Williams

Recoating a symbol of the city

The sculpture is subjected to the harsh array of Minnesota conditions, such as temperatures that can range from more than 100 degrees Fahrenheit in the summer to 30 degrees below zero in the winter. When the temperature changes, the sculpture’s base metal, which is aluminum, can expand and contract through a process called coefficient of thermal expansion and contraction. If the sculpture expands in the summer and then contracts in the winter, the paint could present problems with adhesion at a microscopic level. The sculpture is also wet much of the time. It contains an internal watering system, which keeps the cherry looking shiny, but also creates harsher conditions for the coatings. It is for this reason that marine-grade immersion materials, which are often used to recoat yachts, were chosen for the project. Because the sculpture is displayed outdoors, it is subject to high ultraviolet conditions, which can cause problems such as fading and degradation for highly pigmented colors. Additionally, because the project is literally a piece of art, it has to look good. The first step in the cherry’s refinishing was to remove all of the old coating materials by hand abrasive blast cleaning. This yielded a surprising insight into the sculpture, as it was discovered that

To celebrate the cherry’s reunion with the spoon, those involved with the project, as well as many students and community members, gathered to view the sculpture during a special ceremony. From left are Chris Swingley with Swanson & Youngdale, Inc., which provided the fairing compound services; Joe King, associate registrar of the Walker Art Center who served as project manager for the cherry’s recoating; Gary Papermaster of Industrial Painting Specialists, which did the recoating work; and Tim Williams of Braun Intertec, who designed the specifications and provided critical phase inspections for the project.

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the cherry was constructed of aluminum and not stainless steel as first thought. The Braun Intertec nondestructive examination (NDE) group used a testing method called positive material identification (PMI) to confirm the material’s type. In order to protect the aluminum, a first coat of Sherwin-Williams SEAGUARD MP Multi-Purpose Epoxy Primer was applied, followed by a coat of Sherwin-Williams SEAGUARD 5000 HS Epoxy to protect the primer. Each layer of coating material helps to protect the underlying layers.

Once the first epoxy coats were applied, the process of reshaping the sculpture began. Several coats of Sherwin-Williams Pro-Line Y8004 Pro-Smooth Fairing Compound were used to recreate the original “cherry” shape. A large local commercial and industrial painting contractor, Swanson & Youngdale, performed this phase of the restoration. This portion of the project turned out to be one of the most challenging, requiring the use of personnel with experience similar to that encountered in high-end automotive body work.

Numerous layers of the fairing compound were applied in light coats before being sanded. This process was repeated several times until the final shape was accepted by Joe King, associate registrar of the Walker Art Center who served as the project manager of the cherry’s refinishing. After the final shape was accepted, the coating process began again. Another coat of Sherwin-Williams SEAGUARD 5000 HS Epoxy was applied over the fairing compound and the entire surface of the sculpture.

In late April, the cherry was finally ready to be painted with a Sherwin-Williams Pro-Line Y7001 Deep Gloss Linear Polyurethane red topcoat that was commissioned especially for the project and aptly named “cherry red.” Two coats of red polyurethane were applied and the cherry was lightly re-sanded to remove any remaining surface imperfections or sanding lines. After the final red top coat application, final inspection and acceptance by King, two coats of Y7001 Linear Polyurethane (untinted) clear were applied to discourage fading and aging from exposure to UV rays. The clear coat acts like a pair of sunglasses for the cherry. It helps make the red color last longer, which is important with such an iconic piece.

Ripening the cherry The cherry went through many phases during its recoating and took on many colors before it was reunited with the spoon.

One of the first steps was to remove the old coating materials by hand abrasive blast cleaning, and then prime the sculpture.

Once the first epoxy coats were applied, the process of reshaping the sculpture began. Several coats of fairing compound were used to recreate the original “cherry” shape.

A red topcoat was commissioned especially for the project and called “cherry red.” Later, two coats of clear coat were applied to discourage fading and aging from exposure to ultraviolet rays. The clear coat acts like a pair of sunglasses for the cherry and helps the red color last longer.

This is a stereomicroscopic cross-section of the cherry’s original coatings. It shows that the cherry was repainted several times throughout the years.

CHERRY - Continued from page 4

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By Kelton Barr, PG

One of the geologic hazards that can befall a landowner in this part of the country is the sudden appearance of a sinkhole, when the land surface subsides, then disappears into a gaping hole in the ground. When landowners think of such sinkholes, they often think of the kind found in epigenic karst landscapes. These

Potential dangers lurking below…

are where infiltrating waters recharging the groundwater system create sinkholes and other voids and conduits in shallow, soluble bedrock, such as limestone or dolomite. If the land is mantled by glacial drift, landowners often disregard the risk of this geologic hazard.

However, there is another type of karst process, called hypogenic karst, where upwelling waters in the discharge portions of regional groundwater flow systems can create voids and conduits in soluble bedrock. These voids can be formed deep within the subsurface; subsequent erosion can result in these voids becoming shallowly buried.

Two geologic units in the Upper Midwest that are susceptible to hypogenic karst processes are the Prairie du Chien Group and the Platteville Formation. Both of these formations are composed primarily of dolomitic limestones. Not only can solution voids be formed within such formations, these solution processes can continue upward along a point of weakness, creating a vertical void called a breccia pipe. Breccia pipes are so-called because they may be partially filled with broken rock and debris passing down the pipe from overlying formations. Where breccia pipes extend to near the land surface, they can undermine the surficial soils, eventually causing the overlying ground to collapse, creating a feature that can look like a sinkhole. Both formations can be found throughout the Twin Cities.

Several such collapse structures have occurred in the Twin Cities area, often initially identified as sinkholes instead of breccia pipes. One such collapse structure was documented in 1989 in Mahtomedi. A “sinkhole” appeared overnight, creating a hole that was 42 feet wide and 36 feet deep (Figure 1). The “sinkhole” developed in glacial deposits overlying St. Peter Sandstone. The report of the sinkhole’s characteristics and the subsequent subsurface investigation is no longer available; however, it is now suspected that it resulted from a karstic void originating in the Prairie du Chien, which extended as a breccia pipe through the

overlying St. Peter Sandstone into the surficial overburden.

Another such collapse structure near the metro area occurred more recently in 2005 after a newly constructed infiltration basin filled with storm runoff for the first time. A few days later, more than 1.5 million gallons of water had disappeared into 12 sinkholes that developed on the floor and walls of the basin (Figure 2A). The subsequent investigation determined that the basin was excavated through the surficial glaciofluvial sediments and approximately 35 feet into the subcropping St. Peter

Sandstone and that the basin floor was approximately 80 feet above the underlying Prairie du Chien. Ultimately, the main sinkholes were found to be part of a large collapse structure with a diameter of approximately 50 feet at the excavated surface. This was filled largely with blocks of St. Peter Sandstone in a matrix of glaciofluvial sediment and sands derived from the St. Peter Sandstone (Figure 2B). Another collapse structure with a surface diameter of approximately 30 feet was also found nearby in the basin.

A much older example of a collapse structure can be found in east Minneapolis near the Mississippi River. Seven Oaks Park occupies a sinkhole depression that predates the settling of Minneapolis. On its periphery is an “L-shaped” cavern in the St. Peter Sandstone. Known as Channel Rock Cavern, this was encountered in 1935 as a sewer tunnel was excavated through the area. Figure 3A shows the locations of both the Seven Oaks Park sinkhole and Channel Rock Cavern. The cavern is approximately 725 feet long with passageways approximately 20 to 30 feet high and 35 to 60 feet wide (Figures 3B and 3C).

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Kelton Barr, PG

Figure 1: Collapse structure in glacial drift, Mahtomedi, Minnesota, 1989. Photo courtesy of D. Setterholm.

Figure 2A: Locations of sinkholes. Photo courtesy of E.C. Alexander.

See KARST - Continued on page 7

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KARST - Continued from page 6

The floor of the cavern was originally comprised of blocks of St. Peter Sandstone, and a number of voids and fractures in the sidewalls indicate that the cavern is a prominent void of a larger collapse structure underlying the Seven Oaks sinkhole. The known collapse structure features suggest a diameter at least on the order of 1,000 feet. To date no connection has been found between the cavern and the Mississippi River, either from within the cavern or from the river bluff.

Because of the numerous buried and present valleys eroded into the bedrock in the Twin Cities area, hypogenic karst development and the subsequent development of breccia pipes can potentially be found in the vicinity of these valleys. Unfortunately, unless these collapse structures are already at the land surface, it can be very difficult with conventional subsurface investigations to discern whether the foundation soils are already influenced by an underlying breccia pipe. Studies of hypogenic karst in other regions indicate that collapse structures can reach the surface with as much as 150 feet of burial.

The take-away lesson: When contemplating development, a prudent landowner should speak with a geotechnical consultant about the likelihood of hypogenic karst features that may compromise the project. The absence of surface evidence is not enough!

Figure 2B: This is a collapse structure in the St. Peter Sandstone. The floor of the excavation is on the St. Peter boulders filling the collapse structure. The darkened surfaces around the perimeter are fracture and void surfaces, stained by topsoil during the escape of the basin water through these voids. The tape measure (circled in red) has been extended to its maximum 25-foot length into a fracture.

Figure 3A – Locations of the Seven Oaks Park sinkhole (circled in red) and Channel Rock Cavern (inset map), Minneapolis, MN.

Figures 3B and 3C: Channel Rock Cavern, Minneapolis, MN. Figure 3B shows a transverse perspective of the base of the Platteville Formation comprising the ceiling. Figure 3C shows a side passageway which continues via the hole above the seated person. Photos courtesy of J. Lovaas.

On location

The Professor, Chuck Hubbard, is on assignment in North Dakota fighting floods and other geotechnical disasters. He will return for the next issue to pen Ask the Professor.

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©2009 Braun Intertec Corporation

Questions, Requests and Comments

Charles Hubbard, PE, PG Braun Intertec Corporation 1826 Buerkle Road Saint Paul, MN 55110 Phone: 651.487.7060 Fax: 651.487.1812 [email protected]

This newsletter contains only general information. For specific applications, please consult your engineering or environmental consultants and legal counsel.

Drilling solutions to meet your site’s challenges

Using the largest drilling fleet in the area, Braun Intertec provides a wide range of soil, rock and environmental drilling services. From direct push/probes to CPT rigs, to units that can drill over water or inside existing buildings, we likely have the right rig for your next project. To learn more about how our drilling services can work for you, contact Greg Bialon at 952.995.2380.

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