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V O L 1 4 , I S S U E 4 S P R I N G 2 0 1 2A B R A U N I N T E R T E C P U B L I C A T I O N

While seen as strong, durable products, steel and copper pipe generally don’t last forever. Over time as pipes start leaking and potentially causing

damage within the structure, decisions need to be made for how to address common problems such as pitting and corrosion. Before making the decision for corrective action, investigative work is needed to identify the piping’s current condition. Was this leak just a fluke, or is there damage present throughout the piping? Unfortunately there is no easy way to tell without performing some investigative work.

There are many mechanisms that can cause corrosion or erosion in piping systems and these mechanisms are typically dependent on the conditions of their environment. For example, copper water supply pipe may be susceptible to localized pitting corrosion in low flow areas due to bacteria-forming acidic sulfides. High flow areas may be more susceptible to erosion around fittings from excessive flow often created by the turbulence from not deburring the pipe ends; and from using undersized lines. Corrosion also may occur simply from water with solids or sand in suspension.

Drain and vent piping are common locations for severe corrosion. Most corrosion mechanisms require oxygen and these areas are normally open to the atmosphere with plenty of oxygen to feed the corrosion frenzy. Food and household chemicals that are washed down the drain also can accelerate corrosion. Additionally, cast steel vent stacks are susceptible to sulfide attack. Sulfides dissolve the iron in the steel, leaving only a carbon skeleton behind. Visual inspection of the pipe alone may not cause suspicion, but take a small hammer and tap it lightly, and the pipe will shatter like glass and collapse.

Heating and cooling lines are susceptible to external oxidation corrosion. These lines are usually insulated and sweat in the humid summer months. Insulation materials, if not specified correctly, can contain corrosive material that can leach out and accelerate the oxidation damage. Location of the piping can also be a factor for corrosion. Piping in a city may be more susceptible to acid rains or CO/CO2 emissions from nearby stacks that can penetrate at breaks in the insulation.

When Gum and Duct Tape Just Won’t Work

See PIPING - Continued on page 4

Example of hot and cold water copper pipes. Very fine scattered pitting on the pipe exhibits 30% wall loss. Water sampling predicted that the lines were susceptible to corrosion based on hardness and pH levels.

By Jason Vickers

Nondestructive Examination Group

Example of a sanitary sewer examination where piping was in service for more than 75 years. No significant corrosion was found in this vertical section.

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It doesn’t seem that long ago that sustainability and “going green” were all the rage. The two concepts, though not equivalent, had all the

makings of classic fads. Even though people have grown weary of the buzzwords and empty green products that don’t work or get tossed out just as readily as traditional items, the overall concepts of sustainability have staying power. Why? People are of course concerned about generations that will follow, but more pragmatic are the commercial and economic drivers. For example, if you are working collaboratively with Fortune 100 or Fortune 500 companies, you know that they are seriously tracking and reducing their carbon footprint for branding and economic reasons and if you want to continue working with them, your company may have to take actions to support those activities. This is known as the sustainability of their supply chain. The economic drivers are more obvious: savings on electricity, fuel for heat and vehicles, waste disposal and water drop right to the bottom line. If there are services related to sustainability that can be offered to clients, it gets even better.

Our corporate sustainability program, Project Sage, will be entering its fourth year this spring and is blossoming as it evolves. In concept, it began as a mainly green initiative, focusing on waste and simple energy use reduction. As the steering committee was formed and champions were identified, the concept evolved into a triple bottom line sustainability program, with the foundation concepts of people (wellness, safety and community relations), planet (environmental

sustainability) and profit (how these efforts impact our bottom line).

Where is the “people” part of the equation? It includes our community outreach and charitable giving efforts, wellness initiatives, and safety focus. Besides the standard practices of examining our current practices and setting baselines to determine where we can make positive changes and then executing on those changes, Project Sage also promotes business practices that help our clients and other stakeholders attain sustainable designs in the building process. These practices revolve around the Leadership, Energy and Environmental Design (LEED) principles, and touch all of our business units. The main idea of LEED is the reduction in consumption of energy for the construction and operation of our buildings. Specific Braun Intertec service areas with which we can assist with these sustainability efforts include the following: soils engineering, indoor air quality/industrial hygiene, building sciences, geothermal evaluations, and environmental consulting.

Sustaining a Sustainability ProgramBy Jim DeLuca, PG, jdeluca@braunintertec.com

Environmental Consulting Group

Some of our internal Project Sage “planet” activities include the following:

• Exploring ways to reduce miles traveled by bundling trips, improving driving habits, and reducing unnecessary travel; including a pilot GPS-driven program being tested in more than 20 Braun Intertec vehicles.

• Completed retrofitting of tractor trailer trucks and drill rigs through the Minnesota Environmental Initiative and its “Project GreenFleet” program, reducing particulate and emissions from our older diesel trucks and rigs. http://www.projectgreenfleet.org/

• Cycling in more fuel-efficient vehicles as our fleet ages.

• Improving building envelopes on properties we own (and working with our leasing partners for properties we don’t) to increase our energy efficiency. This includes an “extreme makeover” at headquarters that will include a significant investment in solar panels and geothermal supplement to our current HVAC system.

• Partnering with Agile Frameworks, our technology subsidiary, to examine energy-saving technology options such as cycling in more energy efficient units and modifying shut-down schedules; and to pursue cutting edge technology that helps reduce paper usage.

• Reducing waste at our offices and at company functions.

• Calculating our annual carbon footprint using Greenhouse Gas Protocol methods and evaluating potential areas for improvement.

Since Project Sage was founded in late 2008, almost 300 pounds of junk mail have been elimated from our mailboxes.

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The indoor air quality portion of our Industrial Hygiene group has helped our clients manage and reduce the LEED process of flushing out volatile organic compounds (VOC) contaminants from paint, adhesives, carpeting, vinyl flooring and cleaning materials via air exchanges upon completion of the building. This process can take approximately 30 days of operation to exchange enough air to meet the LEED requirements. Through innovative vacuum canister air sampling, we have been able to reduce or eliminate the 30 days of purging and non-occupancy of the building, saving the contractor considerable amount of time on the schedule and allowing earlier move into the facility, not to mention energy savings.

Critical to gaining LEED points is reuse of existing materials or recycling of those materials as well as recycling of entire buildings. The hazardous building materials portion of our Industrial Hygiene group helps assess the capabilities of an existing structure through evaluation of potentially hazardous materials like asbestos, mercury etc.; while our Building Sciences group performs evaluations on some of the structural capability components of the building, as assistance to the project structural engineer. Through the use of ground penetrating radar, coring drilling of the concrete and evaluation of the strength of the existing reinforcing, an overall picture can be generated of the capabilities of reutilization of the structure.

As the LEED process was modified in 2009, maintaining operating efficiencies and making sure that the building operates the way it was intended was stressed over simply scoring LEED points. This requires the continued management of the building systems and monitoring them to make sure that the energy efficiency is achieved. To this end, our Building Sciences group assesses problems on the exterior envelope and loss of energy out of LEED-certified buildings.

Brownfield sites are especially tricky and really aren’t allotted an appropriate number of points in the LEED system, but there are places in the process that where Environmental Consulting skills are nonetheless important in the redevelopment process. Examples include determining how to manage materials within the site that could be potentially hazardous and preventing them from entering the building through the use of vapor mitigation systems, management of the soils on-site and capping the soils within the site boundaries to prevent leaching to groundwater and human contact. We can also assist in recognizing whether surface water run-off from an impacted site creates an environmental hazard, or if the water may be reused for some of the irrigation systems.

Besides the LEED point for the Brownfield cleanup, our Environmental Consulting staff helps our clients attain credits with engineering and institutional controls that allow impacted soil and groundwater to remain at the site rather than increasing the carbon footprint by removing the contaminated materials. The engineering controls, such as soil vapor mitigation systems or impervious caps, minimize exposure to contaminants; and the institutional controls provide a legal framework for the contaminated materials to remain in place. Environmental consulting efforts also come into play with stormwater management and application of geothermal energy at contaminated sites.

A key component of constructing a high-performance building and boosting LEED points is the building’s HVAC system. As the barriers fall to using geothermal sources for heating and cooling buildings and the positive returns on investment are calculated and realized, Braun Intertec Geothermal (BIG) has become increasingly busy

helping our clients evaluate geothermal for their sites. Our geothermal, civil, environmental, geotechnical and building science

professionals deliver ground heat exchanger solutions and help remove the unknowns that previously contributed to questionable applications, using a systems approach to create cost-efficient, dependable hybrid ground heat exchange (GHX) system designs.

So are sustainability programs sustainable? Absolutely! As long as they are realistic and have positive outcomes for company stakeholders, there is no reason they can’t be sustainable. And if an internal program can churn along while clients benefit from services related to sustainable practices, everyone wins!

A key component of constructing a high-performance building and boosting LEED

points is the building’s HVAC system.

Innovative techniques we use to help clients obtain LEED points:• Site Selection/Development — Reuse of brownfields sites

and providing recommendations and strategies that can reduce or eliminate the extents of disturbance on Greenfield sites.

• Stormwater Design — Geotechnical recommendations to support use of innovative stormwater management such as permeable pavers.

• Materials and Resources — Reuse and recycling of demolition products, using materials that have high reused and recycled content and use of regional materials; and maximize the re-use of contaminated soil.

• Alternative Systems — Specifying alternative foundation systems that reduce soil export and import.

• Geothermal Consulting — Use a systems approach to create cost-efficient, dependable hybrid ground heat exchange (GHX) systems design in facilities.

• Indoor Air Clearance testing (see below) — Flushing out volatile organic compounds via air exchanges to help clients manage and reduce contaminants within the building.

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Fire Sprinkler Lines Susceptibility to DamageFire sprinkler lines are very stagnant environments that can be hosts to sulfur-producing bacteria (SPBs) and other microbes if not treated properly. This damage is very difficult to predict, and some areas of the country have documented higher rates of sprinkler failure due to microbes in the water supply. Plugged lines and/or sprinkler heads are telltale signs of corrosion. The damage is very difficult to locate and highly localized. The corrosion sites have very pronounced tubercule plumes that once removed, reveal a heavy black scale and deep pitting. Mitigating this problem once it has started is problematic because the microbes are protected by the corrosion product. Corrective action calls for the removal of the corrosion in order to kill the microbes.

The National Fire Protection Association (NFPA) has a code requirement that fire sprinkler lines be checked every five years for the presence of the tubercule corrosion. The fire marshal or sprinkler contractor doing the annual system checks may bring the corrosion concern to the attention of the building owner. The check is done at a remote location in the system by draining the system and removing a sprinkler head. The concern is that corrosion by-products inside the pipe may obstruct water discharge from the sprinkler head orifice during a fire. Some jurisdictions are also accepting x-ray of the pipe as a substitute for the expense of draining the system, and in some instances this is more cost effective.

There are a few methods to test for corrosion that provide an accurate account of what is happening inside the pipe. For example,

depending on the piping materials, there are water tests that identify elevated iron or copper levels in supply lines. This may indicate active corrosion, but generally won’t reveal the condition of the piping.

For external corrosion, visual inspection in conjunction with ultrasonic thickness testing is generally adequate. A close visual inspection of the cleaned surface is necessary. Corroded areas can be measured with pit gauges and the adjacent thickness can be obtained with the ultrasonic instrument. The remaining thickness can be determined by subtracting the pit depth from the adjacent thickness.

Another test is profile radiography. The testing can be expensive, but it provides a more in-depth analysis for determining corrective action. With radiography, a profile of the pipe is formed on film or electronic plates, and both internal and external corrosion can be detected. Using the images, measurements can be made of the remaining wall thickness and projections can be made on the pipe’s condition which aids in planning replacement. Ultimately the accuracy in determining the condition of piping systems with this method relies on exercising good sampling and utilizing people

experienced in evaluating corrosion mechanisms. For example, to assess 500 feet of steel piping, it is necessary to sample more than one location to determine the extent of the damage. Selecting a single site in the piping would not provide sufficient data for the whole 500 feet. An example approach may be examining a dead leg, a change in direction, a horizontal section, and a vertical section for every 100 feet of piping.

PIPING - Continued from page 1

Example of a stagnant sprinkler line with bacterial-induced corrosion propagating from the crevice of the connection. The radiograph on the left shows corroded ends with nearly no measurable wall remaining. The right photo shows the internal surface after sandblasting revealing the hole through.

Examples of cooling lines with aggressive external pitting observed after insulation removal. Pit gauging in conjunction with ultrasonics were used to measure remaining wall thickness.

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If signs of rusty water and/or small pinhole leaks (especially on domestic hot water return lines) are being observed it would be a good idea to check the condition of the piping to see if there is a problem before a larger failure occurs.

Braun Intertec was recently awarded an American Council of Engineering Companies of Minnesota Honor Award for our work performed on the Hiawatha LRT and Bike Trail. For this project, Braun Intertec was hired by the City of Minneapolis to provide materials testing and Special Inspection services during construction for this federally-funded project. The City recently completed the construction of a trail link between the Hiawatha Bike Trail and downtown Minneapolis as part of its initiative to enhance pedestrian and bicycle access throughout the City. The $1 million, 800-foot trail link, located along 3rd Street South just north of the Metrodome, required the complex construction of a 25 foot-high gabion block retaining wall to effectively bury the existing wall. The gabion block retaining wall was one of the first projects in the state to be used in the permanent condition, which allowed for reduced construction impacts in the area and a new passage for the trail.

Braun Intertec wins ACEC/MN Honor Award

The 25-foot high gabion retaining wall is comprised of thickly fabricated galvanized wire baskets filled with limestone block and constructed to encapsulate the old wall in order to save demolition fees and to prevent encroachment on adjacent private property. With its limestone block infill and tiered geometry, the wall exhibits a hand-crafted style that fits symbiotically into the area’s geology and architecture.

An apartment building soil stack shows corrosion on the lead flashing, which occurred in less than 10 years. Luckily, the piping is PVC and has not suffered the same corrosion.

PIPING - Continued from page 4

City Piping and Ortho-Polyphosphate Most cities use a variety of treatments and cleaning processes for the domestic water they distribute to make sure it is safe to drink. As a means of mitigating corrosion problems, some cities often add an amount of ortho-polyphosphate to the water to help prevent deterioration of the piping through the entire city system. This chemical addition creates a deposit on the inside of the pipe and adds a level of protection to the pipe from some corrosive elements. However, when the city has a lot of older piping, the function of the ortho-polyphosphate can be “used up” by the older pipe mains that may have lost some their factory lining protection. This results in lower levels of ortho-polyphosphate in the water to provide protection to the pipes inside the building. In some instances, an injection system can be installed that adds additional ortho-polyphosophate to the water to protect against pipe wall loss. On the Cover

Jason Vickers, is a Certified Process Piping Inspector and an Associate Principal for the Nondestructive Examination group at Braun Intertec. Please send your comments or questions to Jason at jvickers@braunintertec.com.

—Steve Flaten, AIAsflaten@braunintertec.com

Building Sciences Group

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Dear Professor: In the old days when stormwater ponds were a nicety rather than a necessity, we estimated infiltration using Hazen’s formula and the D10 particle size. Kozeny and Carman came along and said we needed a full grain size distribution, a void ratio and shape factor. We went to constant head laboratory testing when we couldn’t trust empirical determinations, but then got roped into borehole and double-ring infiltrometer tests in the field. The field approach is good and is often a requirement anyway, but it’s driving the cost of site design up, and sometimes the ponds still don’t infiltrate as expected. Now we’ve got into a project where exterior grades descend below the pond bottom elevation, and we are being asked to evaluate flow through the pond bottom and out to the adjacent slope. We’ve got a cost for performing a pump test that seems high. Can you help me understand/appreciate this upward spiral of scope and cost?

The scope and cost of stormwater pond testing is indeed growing based on regulations and the need to infiltrate as much storm water as possible back into the ground. Hazen’s formula was pretty simple, and Kozeny and Carman’s method looked good because it considered more information, but both methods can yield values of hydraulic conductivity that vary by one or more orders of magnitude. Laboratory constant and falling head tests measure more directly and can be set up to account for relative density, consistency or compaction, but can’t account for in-place variations in those and other factors like composition or layering. (Construction and maintenance of ponds adds several more layers of uncertainty to pond performance, but those are topics for another day.

Every test has its purpose and application, though, and hopefully you are being steered in the right direction with your pump test proposal. Pump tests may be the most comprehensive form of field testing to determine hydraulic conductivity. Unlike virtually all other tests,

which determine conductivity from a small, disturbed or remolded sample in the laboratory or from only a portion of the geologic profile in the field, pump tests can qualify and quantify flow through thick, layered deposits of varying composition and consistency, and from multiple wells (installed in boreholes), and during both pumping and recharge. Such testing isn’t generally warranted for small projects where vertical infiltration is the primary interest, but is of great benefit where horizontal flow is a concern, particularly below or through pond slopes, levees, dams and other impoundment structures. (From a seepage and stability standpoint, horizontal flow is generally of greatest concern where flow will occur through sands or silts). If you want more information on the advantages/disadvantages of various tests to determine hydraulic conductivity, or want to know more about pond infiltration, seepage and/or stability, give me a call. —The Professor

Ask The ProfessorBy Charles Hubbard, PE, PG

chubbard@braunintertec.com

To you whose pond is only half full:

©2012 Braun Intertec Corporation

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Nearly all of us drive, bike or walk on asphalt pavements every day, but very few of us have likely

ever stopped to think how massive an investment these pavements collectively represent. In just over 100 years in the United States, we have gone from the first modern asphalt pavement project to more than two million miles of asphalt-paved roadway -- a truly astounding civil achievement that doesn’t even consider private drives, parking lots, airfields and other surfaces.

The majority of these pavements were constructed in times of plentiful and cheap domestic oil. As a bottom-end product of the crude oil refining process, asphalt’s viscosity and adhesive properties made it the logical choice for the rapid surfacing and renewal of a growing paved road network. The ascent of oil prices, in part, has given pause to this strategy; as more is being done at the refinery to distill less-coveted products such as asphalt into fuel - now the oil beneath our tires looks increasingly valuable.

Simply milling and wasting asphalt materials is therefore no longer a desirable option. This has profoundly shaped the thinking about asphalt pavement rehabilitation: What can be done to re-use or renew this resource in which so much of our infrastructure is intertwined? The answer to that question is increasingly to recycle the pavements in place. Reclaimed or recycled asphalt pavements (RAP) can provide a high-quality aggregate akin to imported materials such as a MnDOT Class 5.

This approach, however, fails to fully utilize the coveted residual asphalt, which is where cold-in-place recycling (CIR) and stabilized full-depth reclamation (SFDR) become vital. Both CIR and SFDR work on the same principal: preserve as much material in place as possible and combine it with a controlled amount of stabilizing or renewing additive such as cement, foamed asphalt or asphalt emulsion to create new asphaltic material. Both are typically capped with a traditional asphalt overlay.

CIR, comparable to mill-and-overlay, requires a structurally adequate base and recycles only a 3- or 4-inch portion of the asphalt layer; SFDR, an alternative to total reconstruction, can be constructed on stable subgrades and will reuse anywhere between a combined 6 to 12 inches of the asphalt surface and underlying aggregate materials. According to the Federal Highway Administration (FHWA), the costs of constructing CIR and SFDR over their traditional counterparts can result in up to 67 and 55 percent savings, respectively. Each also provides structural benefits beyond the use of unstabilized RAP, possibly resulting in a reduction of the costs of future maintenance.

To achieve their maximum benefit, it is critical that CIR and SFDR are applied to the appropriate project. Although most common on rural sections that can tolerate grade changes, city streets and parking lots can also benefit from these processes if properly vetted. A feasibility study may include coring, boring and sampling of existing materials;

visually surveying the pavement surface condition; performing Falling Weight Deflectometer (FWD) testing to evaluate in-place pavement structure and subgrade soil stiffness; and using Ground Penetrating Radar (GPR) to estimate materials thicknesses.

Once a project has been selected, the next step is using a laboratory mix design that incorporates materials

obtained from the project site. In the lab, an experienced technician will prepare samples with several different additive contents in order to test curing, strength, moisture and cracking resistance, and other properties pertinent to the constructability and long-term performance of the stabilized mixture. The selected additive content will be optimized for these properties and will be used in the field by the contractor to guide expectations and control the additive application rate. Diligent field quality control of additive application, moisture content and compacted mix density rounds out the elements necessary to provide a successful and long-lasting approach to the rehabilitation of marginal pavements.

Braun Intertec is fully equipped to perform evaluation, mix designs and field support for your next CIR or SFDR project. For questions or more information please contact the Pavement Consulting Group at Braun Intertec.

Pavement Facelifts Help Iron out Old WrinklesCold-in-place Recycling (CIR) and Stabilized Full-depth Reclamation (SFDR)

By Neil Lund, PE, nlund@braunintertec.com

Pavement Consulting Group

A CIR train at work. Mix designs are recommended for CIR and SFDR to optimize additive contents based on likely field conditions.

11001 Hampshire Ave. SMinneapolis, MN 55438

braunintertec.com

Minneapolis 800.279.6100Bismarck 701.255.7180Cedar Rapids 319.365.0961 Duluth 218.624.4967Fargo 800.756.5955Hibbing 800.828.7313La Crosse 800.856.2098Mankato 800.539.0472Milwaukee 262.513.2995Rochester 800.279.1576Saint Cloud 800.828.7344Saint Paul 800.779.1196Geothermal 320.632.1081

Questions, requests and comments

Charles Hubbard, PE, PGBraun Intertec Corporation1826 Buerkle RoadSaint Paul, MN 55110Phone: 651.487.7060chubbard@braunintertec.com

©2012 Braun Intertec Corporation

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