Borehole Drilling: The Benefits of Multiple Bores

Borehole drilling is a critical factor in geotechnical engineering, which is why we sat down with one of our engineers, Geoff Webster, to learn more about this process and the benefits of multiple bores.

What are boreholes and why is borehole drilling important for geotechnical engineering?

To properly characterize a building site and to design a foundation that will support a structure, a geotechnical engineer must understand the types of soil deposits that will support the foundation. Rarely is the soil homogenous, and the soil profile will vary with depth and may vary across the site as well.

The process of identifying the layers of soil deposits that underlie a proposed structure and determining their physical characteristics is referred to as a Subsurface Investigation. A primary method of gathering subsurface information is the Soil Test Boring. A soil test boring is made by advancing a continuous-flight auger a predetermined distance into the ground. Power to advance the auger is provided by a truck-mounted drill rig. A cutter head is attached to the tip of the auger and auger flights carry loose soil from the bottom of the borehole to the ground surface where it may be observed and collected by the driller.

Why are multiple boreholes advantageous for some projects?

Soil is produced by the weathering of various rocks. Soil produced through weathering processes may be moved by physical erosional processes to locations distant from their origin. These are transported soils and they may be deposited over vast areas in random ways.

Other weathered soil may stay in place atop bedrock as residual soil. Both types of soil may exist in one location with transported soil overlying residual soil. The random nature of deposition means the soil profile of a given site may vary spatially across the site. The manner in which soil is deposited and the grain-size variation in deposited soil determine in part the strength parameters of soil. Structure foundations need to bear upon soils of similar strength to avoid differential movement. Borehole drilling multiple boreholes spaced at the corners and in the center of a proposed structure can ascertain a more complete characterization of soil under the proposed structure than could one borehole placed, say, at the center of the structure.

What are some of the technical aspects of bore holes?

Geotechnical engineers have developed laboratory test methods and mathematical formulations relating the physical characteristics of soil to the strength and performance of soil under loading. A key function of performing boreholes is gathering representative soil samples for use in laboratory testing. Soil samples are typically obtained every five feet of drilling, most commonly using a split-spoon sampler.

This device is pounded into the soil at the bottom of the borehole using a standard weight hammer to collect a 2-foot soil sample. In addition to collecting a soil sample, the number of blows required to advance the sampler a given distance produces a number called the N-value, a measure of the soil’s resistance to penetration. The N-value is the most significant soil value that may be obtained from a borehole, and is a seminal value that has been correlated to many strength and other soil parameters through laboratory testing and mathematical relationships.

What does RMG do to assess how many boreholes are needed?

A subsurface investigation for a given structure or development may be generally divided into three broad phases. Information gathered in each phase before borehole drilling allows RMG to determine a sufficient number of holes.

  • In Phase I we compile existing information regarding the proposed structure such as the type of structure and its intended use, building code requirements, and column and foundation loads.
  • Phase II includes gathering existing site and subsurface information. Such information may be gleaned from geologic maps, soil surveys, or existing soil exploration reports. This information may provide insight into the type of soils to be reasonably encountered and drilling problems that might be anticipated.
  • In Phase III, RMG engineers reconnoiter the site to assess accessibility, drainage patterns, and physical features that may provide clues to subsurface conditions.

While no hard-and-fast rule exists for determining the number of boreholes or the depth to which test borings should be advanced, information gathered during the three phases is used in conjunction with tried-and-true guidelines developed through time. For multi-story structures of light construction and normal loading, for instance, approximately 10-feet depth for each story up to three stories is typical, with at least one boring to a deeper depth to determine depth to bedrock, if present.

For taller structures of heavier loading deeper depths are required. With respect to borehole spacing, building codes and public agencies often specify a minimum number of borings per acre for site development, or a minimum number of borings per length for roadways. Otherwise, judgment and experience are used to ensure sufficient coverage.

Want to learn more about borehole drilling or RMG’s other geotechnical engineering offerings? Contact us today!

 

 

 

 

 

 

3 Drilling Methods To Consider For Soil And Rock Testing

In geotechnical engineering, different drilling methods are used to better understand the soil beneath the surface. There are three common methods to consider: solid stem auger, hollow stem auger and mud rotary. Here is what you should know about each method.

Drilling Methods 1 – Solid Stem Auger

Solid stem augers (SSA) use continuous flight augers which mechanically excavate and continuously transport cuttings to the surface. Augers are available in diameters of 3 to 14 inches. Solid stem augering has a number of advantages. It produces a moderate amount of easily contained cuttings and little or no fluid is required in the drilling process. Thin wall and split barrel sampling operations are supported. Because of lower torque requirements for solid stem augering, smaller drill-rigs can be used, simplifying site maneuvering and often incurring lower costs.

However, this drilling method also has a number of disadvantages. In order to obtain soil samples, the solid stem auger must be removed from the hole and therefore, is limited to stable soils which will not collapse when the augers is removed. Soil sampling during solid stem auger drilling is labor intensive, especially in deeper holes because the augers must be removed from the hole during each sampling procedure.

Drilling Methods 2 – Hollow Stem Auger

Hollow Stem Augers (HAS) are commonly used to set ground water monitoring wells for environmental and geotechnical applications, but can also be used to obtain soil samples. Hollow stem auger drilling uses large diameter (up to 14 inch outside diameter) continuous flight augers which mechanically excavate and continuously transport cuttings to the surface. A center bit, which is attached to the drill rod and bolted to the auger drive cap, is inserted through the cutter head to excavate the center of the boring. As the boring is advanced by adding sections of auger, sections of drill rod are added, maintaining the center bit at the face of the cutter bit.

Hollow stem augering has a number of advantages. The augers act as a temporary casing during and at the completion of drilling to facilitate the soil and water sampling and the installation of monitoring wells. It is relatively rapid and little or no fluid is required in the drilling process. Additionally, this drilling method readily supports thin wall and split barrel sampling.

Hollow stem augering has a handful of disadvantages. For example, it is limited to drilling in poorly lithified to unlithified sediments and to a maximum depth of 150 feet. Shallow bedrock or other hard to drill materials may reduce this depth significantly. High hydrostatic pressures when borehole drilling can cause problems with sand heaving up into the auger during soil sampling and well installation.

Drilling Methods 3 – Mud Rotary

The mud rotary method of drilling uses a drill bit that is mounted on the end of a drill rod and is advanced by the rapid rotation of the bit. The cuttings are removed by pumping drilling fluid (water or water mixed with bentonite or other fluid enhancers) down through the drill rods and bit and up the annulus, between the borehole and the drill rods. The drilling fluid also serves to cool the drill bit and stabilize the borehole walls.

Mud rotary drilling methods have a number of benefits. It is a very fast and efficient means of drilling—efficient drill-rigs can produce several hundred feet of hole per day. Mud rotary is adaptable to a wide range of geologic conditions. However, exceptionally large, poorly stabilized boulder conditions are unsuitable for mud rotary drilling. Sediment sampling is broadly supported and thin wall and split barrel sampling is available.

Mud rotary has a number of disadvantages. The use of drilling fluids may require support vehicles to properly manage and contain both the cuttings and the drilling fluids. The use of drilling fluids may also invade permeable zones compromising the validity of the monitoring well sampling.

RMG’s highly skilled team of geotechnical engineers have the knowledge and experience to assess which of the available drilling methods is best for your project. Contact us today to learn more about our services!

 

5 Things That Great Structural Engineering Companies Do

A beautiful building is nothing if it cannot stand the test of time and nature. This is why we have structural engineering companies! These engineers are the backbone to any well-built structure, which is why it’s so critical to find a reliable and knowledgeable team to help materialize your project.

But not all structural engineering companies are created equal. Here are the top qualities of these engineers to look out for the next time you’re starting a new project.

1)   Structural Engineering Companies Combine Logic With Creativity

Much like architects, structural engineers need to balance logic and creativity in order to solve problems and create the best structure. Specifically, they must be able to come up with several possible solutions to fit clients’ needs that comply with design criteria and fit within construction budget and achieve desired end result.

2)   Solve Problems

If architectural design is the dream, then structural engineering is the reality by which everything is judged. No matter how wonderfully-designed a building may be, if it is not structurally sound, it won’t be around long to enjoy it.

This being said, oftentimes, projects come with their own set up problems, and it’s the engineering company’s job to provide the best possible solutions. A great team will offer multiple options for a particular situation to allow the client to choose which best fits their objectives.

3)   Pay Attention to Details

With virtually no room for error, structural engineering companies must be incredibly detail-oriented. Your engineer should be as familiar with the architecture drawings as the architect is. This will help them understand where the conflicts are likely to occur, and ways to solve them before the problem is even introduced.

4)   Act Like a Partner

Successful project relationships are treated like a partnership, with each side being honest, upfront and respectful of the other team. The structural engineering team you work with should treat you like you are their only client, with prompt communication and excellent customer service.

Successful construction is equally satisfying for the design team as it is for the project owner.

5)   Know Their Capabilities 

Great structural engineering companies know what they’re good at—and also what they’re not. It is important for the structural engineer to understand the architect’s strengths, weaknesses and preferences in order to work best together. Additionally, they should not be afraid to know their professional limits for the sake of the project and the client.

With a strong structural engineering company, your vision can become a reality. RMG offers integrated services that allows us to complete entire projects in-house, making your life even easier.

If you’re looking for structural engineering help, contact us today!

Consider RMG for Your Multifamily Architecture Needs

Ever since the economic crisis in 2008, multifamily development has led the way in housing recovery. In fact, from 2012 to 2014, multifamily units increased 42%, largely due to a high demand for rental properties. If you’re looking to develop in this sector, we break down the specifics of multifamily properties and why you should consider RMG for your multifamily architectural needs.

How does multifamily architectural design differ from single-family design?

Instead of thinking and shaping space for a family, couple or an individual, the architectural designer must think about not only the micro (single occupant), but also the macro (all occupants in the group of units). How do we provide a grounded (health), inviting (welfare) and safe (safety) experience for all users?

That’s what we design.

But beyond the basic needs of a multifamily unit, RMG takes it a step further, ensuring the client is satisfied with the end result. We achieve this through the following principles.

Delight

Most single-family residence clients want something that pleases them—and rightfully so; however, multifamily architecture provides an opportunity to make a lasting design impression upon the contextual fabric for an entire populace.

Firmness

Hardiness also plays a role as many people are expected to use the product (the building). The materials and details should be at a consistently high level to take abuse over the lifespan of the building, while balancing the art of multifamily architectural design. We put ourselves into the shoes of the client and building ownership by asking: what is economical and also aesthetically pleasing?

Commodity

Higher energy demand and efficiencies are a requirement for multifamily buildings, and are stressed much more than single-family residences. We always think about how we can leverage our designs to reduce building energy consumption.

What type of multifamily projects does RMG like to work on?

RMG has the experience and expertise to design small to mid-sized multifamily structures. We relish the opportunity to successfully provide delight, firmness and commodity while meeting our clients’ and building owners’ expectations and requirements.

What does RMG do differently when it comes to multifamily architecture?

RMG is focused on the budgetary limits and requirements of all projects across the spectrum. We understand that we are not creating architectural designs for ourselves, but for our clients, and we always strive to produce thought-provoking designs when and where applicable.

What are some multifamily architecture examples RMG has worked on?

We have worked on an array of multifamily projects—ranging in size and purpose. Here are a couple examples of our work:

MULTIFAMILY ARCHITECTURE

Are you looking into multifamily development? Contact us today to speak to our team about RMG’s multifamily architecture capabilities.

 

3 Reasons Why You Should Consider Wood Framing – RMG Engineers

Structural engineering is the reason we have so many wonderful buildings that have stood the test of time. This discipline is responsible for understanding a building’s strength and stability, and how it will react to its environment and other external stimuli. Throughout the centuries of building structures, engineers have worked with various materials, from adobe bricks to steel beams, but one material has proved to be particularly advantageous for many projects: wood. Specifically, wood framing is one of the most popular materials used to frame projects such as homes, small commercial developments and multi-family units.

Speaking with RMG’s Structural Group Manager, David Schmidt, we learned more about the basics of wood framing and all its benefits, challenges and practical applications.

Wood Framing Benefits

  1. Renewable

As the only renewable building material, wood is the smart choice for environmentally-conscious builders. It takes less energy to extract, manufacture and transport wood and releases fewer greenhouse gas emissions than both steel and concrete. Additionally, planting new trees in place of the ones used for framing helps combat climate change. This is because of the tree’s natural process of converting carbon dioxide into oxygen (photosynthesis).

With RMG’s commitment to the environment, choosing wood framing for many residential and light commercial projects just makes sense.

  1. Better Insulation

Because wood offers “higher levels of thermal resistivity versus other framing materials” (about four times more than steel or masonry), wood framing is more energy-efficient for building and the client post construction. This is due to the cellular structure of wood, which naturally has air pockets inside of it. These high levels of thermal resistance are especially helpful in Colorado’s cold winter climate.

  1. Easy-to-Use

Wood requires fewer certifications and less technical skills than other materials such as concrete and steel. Additionally, it does not need welding or other special techniques that can add to the timeline and budget of a project. Wood is also a readily available, “off the shelf” product that is easily obtained at local big box stores. Finally, Wood is easy to maintain and repair as it ages, and it can be exposed and finished, providing an aesthetically-pleasing structural system. Wood can be used in a variety of structures, from residential to clubhouses to multifamily units, as well as commercial buildings.

Wood framing benefits

Issues With Wood Framing

  1. Deterioration

Because it is a natural material, wood is considered nutritious for many insects, such as: termites, beetles, ants and even some species of bees. Additionally, wood is particularly susceptible to fungi due to its carbon and nitrogen contents. Fortunately, these issues can typically be avoided with construction techniques such as coating, drying and applying wood preservatives, as well as providing adequate weather proofing to seal the exterior of a building.

  1. Fire Hazard

Arguably the most well-known issue with wood is that it can catch on fire easily. Considering it is made mostly from organic carbon and hydrogen compounds, adding oxygen to the mix can cause the wood to burn. To prevent this risk, fire retardants are used to reduce the wood’s flammability.

Wood framing is a reliable and long-lasting solution for your structural engineering needs, which is why it is so commonly used. If you’re looking to build a residential or small- to mid-commercial project, consult with a professional. This is especially important in states like Colorado where things like snow loads need to be considered. To schedule a consultation with our experienced team, click here.

How to Find Reliable Denver Commercial Architects

denver commercial architect

Denver commercial architects have the privilege and responsibility to alter a city’s skyline for years to come, so it’s critical that they understand both the art and science of the craft. The Mile High City has shown consistent growth and exhibits no signs of slowing down, with developers from all over the country looking to build in a competitive market.

Looking for a commercial architect can be a tedious endeavor, but it’s important that you find an experienced and reliable professional who can help you make your vision a reality. In addition to helping bring your dream to life, an architect has to be aware of the plethora of logistics associated with the job, such as zoning laws, permitting, functionality of the space and more.

So how can you tell if an architect is reliable? One of our veteran architects, Keith Moore, shares his insight on the craft, using three traits from Randall Satchell’s “Qualities of an Architect.”

  1. Ready to Listen

“Listening is an endangered art form…The architect must know how to listen and facilitate productive, engaging discussions leading to successful products.”

One of the main roles of a commercial architect is to see their client’s vision through to fruition. While it is their responsibility to ultimately bring the building to life, it’s key that they understand what the client wants, which can be attained through active, attentive listening.

Attentively listening will bring to light what the client likes, and more importantly, as Moore states, doesn’t like. But a reliable architect doesn’t just listen to their client; they apply logic and reasoning as well to help bring an idea to life.

READ MORE ABOUT RMG’S ARCHITECTURAL SERVICES

  1. Logical Reasoning

“Reasoning, pattern recognition, and deduction should be both a strength and a natural pleasure [for architects].”

Denver commercial architects understand that there are a myriad of logistics that need to be sorted before a project may begin. Moore uses the example of a restaurant when he explains that an important role of an architect is to understand the functionality of the space.

With his previous experience working in a kitchen, Moore shares that there is a specific order to how restaurants are designed. For instance, he notes that a reputable architect understands that there need to be separate doors for serving and clearing plates (because the last thing a customer wants is to see their food coming out of the same door as a stack of dirty plates).

Besides the functionality of a space, commercial architects have a responsibility to abide by state and local codes and regulations. Making sure permits have been obtained and necessary paperwork has been submitted will help make your dream a reality.      

  1. Imagination

“Imagination is crucial to problem solving, which often requires creative approaches to more efficiently arrive at successful results.” 

Of course, an architect is not an architect without the ability to create what does not exist. Skilled Denver commercial architects understand the “sticks and stones” concept, as Moore describes it.

Architectural design is a puzzle that requires out-of-the-box thinking to achieve a client’s wishes, but this imagination is dictated by priorities and logistics. “How can we achieve the best with the least amount of effort and cost?” Moore asks. A qualified architect will take all of the known factors under consideration to create a space that fulfills the requirements, but also stands out from the mold of its predecessors. Which is why architecture is not just a science, but an art form as well.

No matter what commercial space you’re looking to create, RMG has a staff of highly experienced architects and engineers to get the job done at every stage of the process. Contacts us today to learn how RMG can help make your idea a reality!

5 Things to Look for in a Structural Engineering Firm

The Pyramids of Giza, the Acropolis of Greece, the Coliseum of Rome—what do all of these architectural marvels have in common? Structural engineering that has stood the test of time. No matter your building project, having a trustworthy and reliable structural engineering firm can ensure your legacy will stand tall for years.

 

Top 5 Things to Look for in a Structural Engineering Firm

Our senior commercial engineer, Mark Weidhaas, breaks down the top five qualities of a structural engineering firm you should look for:

1. Longevity

Experience, quality construction documents and competitive pricing are key for any structural engineer to stay in business. RMG has been serving the Colorado Front Range and beyond since 1986, and have over 30 years of experience in building relationships with other design professionals, general contractors and builders. A longstanding firm with great relationships will provide the quality, timeliness and fair cost required for your project.

2. Responsive

No matter the size of your project, it deserves a structural engineering firm that will respond quickly to your concerns and field comments to keep it on schedule. At RMG, our team of design professionals is led by a highly-skilled project manager who is designated as your point of contact. A responsive firm will keep you informed with regular communication, reply to questions and concerns in a timely manner and makes you feel like you are the only client.

3. Staffing

Having a talented, flexible team is essential for the building experience. Having a dynamic group of professionals all under one roof helps projects move forward faster and more efficiently. At RMG, we balance staffing to be available on both large and small projects. We currently have 85 skilled engineerstechnicians and professional staff eager to work with you, solving problems and coordinating with your team to make the project successful.

4. Experience

No two projects are alike. Because of different construction materials, building codes, geotechnical foundation restraints, contractor abilities, etc., it’s important to have a structural engineering firm with experience in many types of jobs. RMG has the experience to design and clearly convey those designs in our construction documents. Our 7 structural professional engineers have a total of 175 years of experience in solving problems between them. We know a thing or two, because we’ve seen a thing or two.

5. Licensure and Continuing Education

A successful structural engineer does not stop learning once out of school. It requires a life-long education using new technologies and ever-changing building codes. RMG’s professional engineers are licensed in 25 states, including Colorado, with the capability to become licensed in additional jurisdictions if needed. Our engineers keep their knowledge current by regularly attending continuing learning programs and are involved in the engineering community by serving on regional building department boards. They volunteer their time as leaders of engineering and technical society organizations, such as: ACEC, AISC, CRSI, SEA Colorado, ABC, NSPE and PTI. Two of our principal engineers were Colorado State Presidents of the National Society of Professional Engineers, in 2006-2007 and 2009-2010.

Having a dedicated structural engineering firm will help your project stay on schedule and under budget. We have a wide range of integrated services with offices all across the Front Range to help your dream become a reality!

Contact us today or learn more about our structural engineering services here.