Land Clearing, Grading and Site Preparation, Many Methods are used, what is Best for You?
With a major project to construct, a land owner has to start with raw space, have you ever thought about land clearing a new piece of property? The site of a major construction project somewhere in the world, with local laws, methods and customs, and doing it on your own? Did you ever happen to think about the other details; does that land clearing have to adhere to rules and regulations unique to a specific area? Are there any special regulations regarding water runoff, storm water collection and distribution, or certain trees and waterways that are protected by law in that local area? Where should you start? What is the equipment you need for this job? Where should you start? What equipment do you need for that unique job? Are there existing underground utilities that may be damaged? Are there any abandoned underground or above ground structures that will need special removal? All these questions and more will be answered in advance, by a competent major projects consulting firm, one like Nationwide Consultants, LLC
A firm ready to begin a project involving raw land with intention of constructing on it, needs the services of competent consultants like Nationwide Consultants, LLC. Chances are that it needs to be cleared of rocks, trees, bushes and any existing structures above and beneath the ground as well as hidden junk that may have accumulated over the years. Other questions may arise that can only be answered with research and the experience to know what to look for. More importantly; it becomes essential to get the answers needed for unique situations, in a timely and efficient reporting system.
The thing to remember is; land clearing is a complex task involving heavy equipment, knowledge of laws and permits, experience with the unexpected and adequate planning. The raw land to be graded following a comprehensive surveying process may need additional services including grading grubbing, tree removal and problems that may only exist on that piece of land.
Today, the methods of land clearing have undergone tremendous change. While in the past, Project Consultants simply resorted to techniques like burning and bulldozing; today, residential and commercial property owners are expected to use various methods available at their disposal, which are much more efficient and environmentally friendly.
Many of these modern techniques of land clearing are environmentally friendly, conforming to local laws that may exist and offer safer alternatives to traditional means. The list of land clearing equipment can range from simple hand held tools to large bulldozers and shearing devices. The larger the trees are that need to be cleared, more powerful and commercial tools will be required. If you ask experts as to which land clearing method is the best; chances are that you will get varied answers.
The method chosen depends greatly on what is done with the cleared trees and bushes. One thing is sure, Land Clearing and Site Preparation is not a job for armatures. An experienced consulting firm like Nationwide Consultants, LLC can take a lot of the guess work out of a major construction project from the first tree removed to the final landscaping if the project, and everything in-between. A good consulting firm takes all the guess work out if a major project, where guessing is not an option.
Basic Methods of Land Clearing Available Today
Bulldozing
For most residential and commercial property owners, choosing Consultants to help with the Site Preparation Services process depends on cost and time. From this viewpoint as well, especially for large properties, bulldozer method is the cheapest, fastest and most well known. However, simply pushing the bushes and trees does not kill them; moreover it leaves the soil uneven. Large bulldozers are not easy to maneuver. They often knock off the bark of hardwoods and oaks the project may want to keep as part of the final look of the properties landscaping. This has a result of leaving these prime trees scared and susceptible to oak wilt, possibly destroying the trees you are trying to save for the finished look of the property. Hence smaller machines are sometimes required to be used like skid-steer tractors (BobCat) with hydraulic shears. These machines are driven into trees like cedar, cut-off at the ground, picked with shears and carried off for burning. This method ensures less damage to surrounding hardwoods.
Chain Saw Method
Chain saw method for tree removal is an alternative to bulldozing, although it is slower and also a lot more expensive due to the fact that additional personnel are needed beyond that needed for the Bulldozing method. The chain saw is definitely not for most large sites – it requires training and expertise which raises the overall cost. This method is often considered a better alternative to bulldozing as it leads to less land disruption and erosion. The tree stumps are basically left as they are and this provides leverage to enable bulldozers to pop the stump out of the ground. You can also be selective and choose to cut one tree but leave the next and also opt for a barrier between the site property and neighboring properties. Large trees like cedar, once removed, can be burned, chipped into mulch or hauled off.
Earth Grading
The building site also has to be graded and freed from rocks and low growing plants during the site preparation process to make way for lawns, Driveways, parking lots, storm drains and buildings. For this purpose the site will need large backhoes and skid loader equipment. The owner/developer can choose to filter large rocks during this process and use them later for landscaping purposes. The dirt can also be reused later for finishing the grading, once the construction is over. Landscaping services providers can guide you regarding this aspect. Coordinating every aspect of the construction process is what Nationwide Consultants, LLC does, we take care of the details.
Silt Fencing
Silt fencing is a temporary barrier of geotextile fabric, which is placed in land clearing projects and construction sites to prevent sheet erosion during the site preparation and construction process. The disadvantage of this is that it requires maintenance and also is susceptible to UV deterioration. Forest and wildlife laws may require you to place the silt fence to prevent mud and construction waste from going into neighboring property, streams, lakes and ground water.
Before You Proceed
Before you proceed with a land clearing and construction project, it is of importance to see if there may be valuable timber on the grounds. In the case that valuable hardwood timber exists in sufficient quantity, a timber buyer may trade the clearing costs for the lumber they can remove and sell, there by doing the clearing cost free. Nationwide Consultants, LLC can help you in this regard; contact us for more information and any questions on Site Development and Construction Services supervision in general.
Regional Regulations
Apart from these considerations, land owners need to check with their local, provincial and state officials as there may be several rules regarding timber permits, silt framework, mulching, burying of organic materials etc. Some regulations allow you to destroy the trees by fire while others might require you to pulverize the foliage and undergrowth into mulch. For example, St John’s Florida has following regulation regarding tree removal:
“Tree removal on lots less than one acre with an existing home or structure does not require a tree removal permit, as long as the tree does not lie within a conservation area or buffer. However, the lot where the tree is to be removed must maintain a minimum of 80 cumulative tree inches per acre.”
It is laws like this one in Florida, typical of local laws that exist all over the world, unique to a specific area that make the use of a consulting firm like Nationwide Consultants, LLC both useful and cost effective.
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Building a Green Life Cycle Facilities Assessment: a Facilities Impact on it’s Community and the World over its Projected Life
Building a Green Life Cycle Facilities Assessment in Practice balances benefits against the costs of resource consumption from fabrication to deconstruction of a building.
By comparing the whole building and individual components, architects and engineers can calculate environmental impacts at the outset of a project, and refine those calculations as the project proceeds, to show owners what the potential is for a proposed design option to cause or mitigate global warming, acidification, eutrophication (excess nutrient leaching that causes, for example, algae bloom), fossil-fuel depletion, smog formation, ozone depletion, ecological toxicity, and water use.
The life-cycle assessment (LCA) process usually includes all participants in the planning, design, construction, and operations of a facility and begins with setting the goal and scope of the LCA. The LCA might focus on one specific impact, such as global warming potential. Step two, inventory analysis, would then quantify the input and output of each element of the design being analyzed to determine how many units of greenhouse gases will be released or embodied (in this case, measured as CO2 equivalents). The impact could then be analyzed, based on the set goals, and decisions can be made based on the resulting interpretation.
The process is heavily dependent on the regional accuracy of government databases and hampered by the one-off nature of building design and construction. Government and nongovernment organizations are currently working to refining both the databases and the software that crunches the numbers to make sense of the reams of raw data for non-technical decision makers.
The Rationale
As the architectural and construction industries increasingly emphasize sustainability, more comprehensive methods are being developed to evaluate and reduce environmental impacts by buildings.
It recognized in the current construction environment, that limitations of LCA—particularly the current nascence of client demand and comprehensive databases make Green Life Cycle Assessment a rarity—one that looks ahead to the next emerging discipline in measuring building design, construction, and operations sustainability.
Some of the more outstanding and relevant assessments preformed in addition to all the usual LCA factors within a Green Life Cycle Assessment include:
Global Warming Potential (GWP)
Global Warming Potential, or GWP, has been developed to characterize the change in the greenhouse effect due to emissions and absorptions attributable to humans in a Green Life Cycle Facilities Assessment. The unit for measurement is grams equivalent of CO2 per functional unit of product (note that other greenhouse gases, such as methane, are included in this category, thus the term “CO2 equivalent” is an impact and not an emission).
Acidification Potential (AP)
Acidifying compounds emitted in a gaseous state either dissolve in atmospheric water or fixed on solid particles. They reach ecosystems through dissolution in rain. The two compounds principally involved in acidification are sulfur and nitrogen compounds. The unit of measurement is grams of hydrogen ions per functional unit of product.
Eutrophication Potential (EP)
Eutrophication is the addition of mineral nutrients to the soil or water. In both media, the addition of large quantities of mineral nutrients such as nitrogen and phosphorous results in generally undesirable shifts in the number of species in ecosystems and a reduction in ecological diversity is considered in a Green Life Cycle Facilities Assessment . In waterways, excess nutrient leads to increased biological oxygen demand (BOD) from the dramatic increase in flora that feed on these nutrients, a subsequent reduction in dissolved oxygen levels, and the collapse of fish and other aquatic species. The unit of measurement is grams of nitrogen per functional unit of product.
Fossil Fuel Depletion
This impact addresses only the depletion aspect of fossil fuel extraction, not the fact that the extraction itself may generate impacts. The unit for measurement is mega joules (MJ) of fossil-based energy per functional unit of the product. This category helps demonstrate positive environmental goals, such as reducing the energy needed to produce a product, or such as producing a product with renewable, nonfossil- based energy.
Smog Formation Potential
Under certain climatic conditions, air emissions from industry and fossil-fueled transportation can be trapped at ground level, where they react with sunlight to produce photochemical smog. The contribution of a product or system to smog formation is quantified by this category. The unit of measurement is grams of nitrogen oxide per functional unit of product. This highlights an area where a regional approach to LCA may be appropriate, as certain regions of the world are climatically more susceptible to smog.
Ozone Depletion Potential
Emissions from some processes may result in the thinning of the ozone layer, which protects the earth from certain parts of the solar radiation spectrum. Ozone depletion potential measures the extent of this impact for a product or system. The unit of measurement is CFC-11 per functional unit of the product.
Ecological Toxicity
The ecological toxicity impact measures the potential of a chemical released into the environment to harm terrestrial and aquatic ecosystems. The unit of measurement is grams of 2, 4-dichlorophenoxy-acetic acid per functional unit of product.
Water Use
Water resource depletion has not been routinely assessed in LCAs to date, but researchers are beginning to address this issue to account for areas where water is scarce, such as the western United States. The unit of measurement is liters per functional unit is used in a Green Life Cycle Facilities Assessment.
Understanding Common Pollutants on the Construction Site with Nationwide Consultants, LLC
There are a number of potential storm water pollutants that are common to a developing construction site, whether on virgin land or a recycled site. The soil-disturbing nature of construction activities and the use of a wide range of construction materials and equipment are the sources of Common Pollutants on the Construction Site and contaminants with the potential to pollute storm water discharges.
One of the items Nationwide Consulting LLC personnel can monitor is the over looked area of ground water and storm water pollutants caused by new construction site preparation. Without proper planning, due diligence and close attention to these details, the owners as well as the contractor could be subject to major and avoidable fines and penalties for many of the Common Pollutants on the Construction .
Common construction activities that increase the potential for polluting storm water with sediment include:
Clearing and grubbing operations
Demolition of existing structures
Grading operations
Soil importing and stockpiling operations
Clear water diversions
Landscaping operations
Excavation operations
There are other areas of concern, areas that Nationwide Consulting, LLC can monitor and circumvent before they become an issue. When a large corporation has a remote construction project, often details become overlooked, Nationwide Consulting, LLC becomes that never closing eye on the job, that presence that keeps your foot in the game. Where we are involved, no “unplanned mistake” or “overlooked detail” is ever acceptable. Planning, details, due diligence and supervision are the difference between under budget and ahead of schedule or vastly over budget and late on delivery of a project.
Common construction materials with the potential to contribute Common Pollutants on the Construction , other than sediment, to storm water, and potentially derail a project with local and state governments include the following:
Vehicle fluids, including oil, grease, petroleum, and coolants
Asphalt concrete (AC) and Portland cement concrete (PCC) materials and wastes
Joint seal materials and concrete curing compounds
Paints, solvents, and thinners
Wood products
Metals and plated products
Fertilizers, herbicides, and pesticides
Any of these pollutants have no business getting into storm water, or run off of any kind from a properly run construction site, unless that site is lacking proper authority and site management.
Construction-related waste must also be managed to prevent its introduction into storm water. Typical waste and Common Pollutants on the Construction on construction sites includes:
Used vehicle fluids and batteries
Wastewater from vehicle cleaning operations
Green waste from vegetation removal
Non-storm water from dewatering operations
Trash from materials packaging, employee lunch/meal breaks, etc.
Contaminated soils
Slurries from sawing and grinding operations
Wastewater/waste from concrete washout operations
Hazardous materials waste
Sanitary waste
MONITORING AND INSPECTION PROGRAM
Nationwide Consultants, LLC Engineers are responsible for ensuring that construction site personnel monitor the contractor’s water pollution control practices and maintain compliance with the approved project parameters.
Review the Storm Water Quality Construction Site Best Management Practices.
Nationwide Consultants, LLC personnel with storm water responsibilities all familiarize themselves with Best Management Practices regarding pollutants escaping into the storm water systems of Florida. In particular, they become familiar with (1) the rainy season dates for our area, (2) the requirements for soil stabilization and sediment control and the BMPs for the season and specific rainfall for areas affecting the construction site.
Review the Project Plans.
Naturally Nationwide Consulting, LLC Reviews the Project Plans in the context of storm water pollution control. We visualize storm water run-on and runoff flow patterns when reviewing the plans. We review the general layout and existing drainage courses. Identify potential problem areas where storm water may run onto the site or discharge off site.
Identify the locations where structures are being constructed or modified. We are familiar with the right-of-way and easement limits. We determine the limits of clearing and grubbing activities. Identify the project phase or stage. Try to determine Environmentally Sensitive Areas (ESAs).
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Major Construction, Building in Remote locations can Face Unique Challenges
Nationwide Consulting, LLC has Extensive Experience to Meet Those Distant Challenges
By Robert Hanson
Remote locations have many challenges that are not faced when building in populated areas. Successfully building in remote locations takes seasoned, experienced professional construction management to overcome those challenges. Nationwide Consulting LLC has extensive experience in successfully completing projects that are building in remote locations.
Concrete is the foundation of any construction project working and building in remote locations means you will need to have a portable concrete batch plant to produce your concrete. The challenges of operating a batch plant are many and close attention must be paid to every aspect of the operation. Here are some of things you need to know that will keep your remote concrete operation on track.
Inconsistent concrete slump test
Simply defined, slump is a measure of the consistency of fresh concrete. The slump test is a very simple test. The slump cone is a right circular cone that is 12 inches high. The base of the cone is 8 inches in diameter and the top of the cone is 4 inches in diameter.
The test is carried out using a mold known as a slump cone. The cone is placed on a hard non-absorbent surface. This cone is filled with fresh concrete in three stages. Each time, each layer is tamped 25 times with a rod of standard dimensions. At the end of the third stage, concrete is struck off flush to the top of the mold. The mold is carefully lifted vertically upwards, so as not to disturb the concrete cone.
Only a true slump is of any use in the test. A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which the slump test is not appropriate. Low workability mixes; having slump 10 – 40 mm are used for foundations with light reinforcement, medium workability mixes; 50 – 90 for normal reinforced concrete placed with vibration, high workability concrete; > 100 mm.
A slump is interpreted using the method below and is a direct result of how the concrete is mixed.
Rarely will a laboratory mix be entirely suitable under the variable field conditions. Adjustments to the amount of water and add mixtures are commonly required. Even with sophisticated computer control batch plants, batching tolerances can affect slump control. Water cement ratios can vary by about 0.01 however with uniform mixing batching tolerances shouldn’t affect slump by more than 1/2 inch.
ASTM C 94 requires total mixing water which influences slump in water -cement ratio is to be measured within plus or minus 3%. The plant total mix water includes free waters in the aggregate and aggregate should never be loaded dry.
Measuring and correcting for fine aggregate moisture content can significantly change slump. Many batch plant operator’s measure sand moisture content in the morning as temperatures rise during the day and the aggregate dries more water is absorbed reducing concrete slump. To indicate changes in sand moisture content the plant operator should be using a properly maintained and calibrated Sand moisture meter. At the Kwajalein site the wind is typically blowing 15 to 20 miles an hour with 85 plus degree air temperature therefore a moisture content in the morning is quickly diminished as the day goes on therefore it is important that all aggregate be continually kept wet and moisture content measured several times a day.
Mixing
To achieve a uniform concrete batch ASTM C 94 requires a minimum of 72 – 100 revolutions at mixing speed. Additionally, the volume of the mixed concrete should not exceed 63 % of the total drum volume. When the truck arrives on-site turn the drum another 30 revolutions at mixing speed to reduce any segregation that may occur during the haul. To assure that the concrete is within permissible slump range the load should be dumped within 30 minutes upon arrival on site or after initial adjustment of water whichever is later.
The first and last quarter yard discharges are exempt from this requirement. ASTM C 94 permits on site slump adjustment and allows for some adjustment if the truck arrives on site with the concrete slump less than specified.
Concrete to be pumped usually requires a High slump adding superplasticizers on site instead of water can attain a pump-able mix without increasing the water cement ratio.
Common Issues & Corrective Actions
The project is working with a designed mix with the expectation of achieving a 7 slump when the desired slumps are not met the following actions should be taken:
Batch plant maintenance records should be checked to assure that scales are properly calibrated and batch plant is functioning at mix design requirements.
Aggregate stock piles should not dry but rather wet tested for moisture content when loaded into batch plant.
Supply water and aggregate should be checked for salt content.
Truck volumes and mixing revolutions should be monitored closely.
Batch plant maintenance and records
For an effective production & delivery of concrete, all plant & equipment should be maintained in a clean and efficient working condition. To achieve this, checklists are used by the batching plant personnel. These checklists include daily checks, weekly checks, monthly checks and quarterly checks. Checklists must be prepared in such a manner so that they cover the following 3 basic components of ready-mixed concrete batching plant.
Storage & handling equipment
Batching & mixing equipment
Transporting equipment (Mixer & Agitator)
Weekly Storage and Handling Equipment Checks
Check the area under plant for spillage and trace source
Check all drains and traps are clear. Check cleanliness of yard
Check to maintain settlement pits, recyclers and wash down areas in efficient working order
Check all storage bins and doors for efficient operation
Check conveyors, boom scrapers and bucket elevators for free running and wear and adjust as necessary
Routine checks and servicing on loading shovels
Routine checks and servicing on compressors
Daily Checks for Batching and Mixing Equipment
Check and adjust tare weights and clean weight dials (if applicable)
Check to ensure that weighing hoppers empty properly.
Check to washout central mixer drum or pan
Weekly Checks for Batching and Mixing Equipment
Check and maintain that all hoppers and doors are in clean and efficient working order
Check central mixer blades, paddles or arms for wear and tightness and adjust as necessary
Check and remove any cement or concrete build up in the mixer
Check and shack out cement silo filter sock (if applicable) and maintain in efficient working order.
Check dust seals on cement hoppers for wear
Check and clean knife edges or load cells on weighing equipment
Check calibration of moisture meter if applicable
Check oil levels on air-line lubricators
Drain water traps on air lines
Check rams and air lines for leaks
Check pipe-work for leaks and wear
Check wiring and electrical apparatus for correct operation and over heating
Routine checks for greasing of bearings and gears
Routine checks and servicing on central mixers
Monthly Checks Batching and Mixing Equipment
Check calibration of all weigh scales
Check calibration of water meter
Check calibration of admixture dispenser
Quarterly Checks Batching and Mixing Equipment
Inspection and testing of all weigh scales over their complete operational range
Routine oil changes in gearboxes and oil baths
Daily Check Transporting Equipment – Mixer & Agitator Units
Check and wash out truck mixer drum
Monthly Checks Transporting Equipment – Mixer & Agitator Units
Check mixer unit for blade wear
Check operation of revolution counters, if fitted
Check calibration of truck mixer water meter
Common Issues & Corrective Actions
Require maintenance records be provided by plant operator weekly to Owner
Make unannounced spot checks of records to actual plant conditions
Concrete Honeycombing
Consolidating and compacting freshly placed concrete with an internal vibrator is a fairly simple and straightforward process. A majority of honeycombing, rock pockets, sand streaks, pour lines and voids can be avoided by taking the time to properly train and educate employees on the proper use of internal vibrators and the future problems that may arise from incorrect vibration practices.
Freshly placed concrete can contain 5 percent to 20 percent entrapped air, ultimately reducing the concrete’s density. Concrete with a high percentage of entrapped air will likely have a reduced strength and increased permeability, which will greatly reduce the durability of the concrete product once in service.
In general the two most common mistakes made when using an internal vibrator are removing the vibrator head too quickly and dragging the vibrator head through the concrete. The properly trained individual will also realize that dragging a vibrator through the concrete will form a mortar channel in the concrete, creating a structurally weak area in the finished product.
When training individuals on the proper use of internal vibrators, it is important to explain the basic principles of how an internal vibrator works. Simply put, vibratory impulses liquefy the mortar, drastically reducing the internal friction between aggregate particles. The mixture becomes unstable, allowing entrapped air to rise to the surface while the heavier aggregates settle under the force of gravity into a dense matrix.
The amount of time that the vibrator must remain in the concrete will depend on the vibrator’s frequency and amplitude and the concrete’s workability. The frequency is the number of vibration cycles per minute and is often presented as revolutions or vibrations per minute (rpm or vpm). Frequency will have an effect on lighter masses, moving sand and slurry around aggregate and ultimately causing the mortar to liquefy. The amplitude is the maximum distance a point on the vibrating head moves from its position of rest. Amplitude will have an effect on heavier masses, moving coarse aggregate and ultimately determining the radius of action or influence. The radius of action is the area of concrete influenced by the vibrator.
Smaller-diameter vibrators will have higher frequencies and lower amplitudes, while larger-diameter vibrators will have lower frequencies and higher amplitudes. As a general rule, the diameter of the vibrator should be a quarter of the wall thickness of the product being cast. Smaller-diameter internal vibrators with higher frequencies are typically used for consolidating higher-slump concretes.
When using internal vibrators it is important to lower the vibrator vertically into the concrete, allowing the head to descend under its own weight. Internal vibrators should not be forced down into the concrete. The vibrator head should penetrate previously placed lifts of concrete by 6 inches (150 mm). If there is a considerable amount of time lapse between the placements of subsequent lifts, it may be necessary to re-vibrate the previous lift prior to placing additional concrete to minimize the potential for pour lines and cold joints.
Vibration times will vary depending on the size of vibrator used, the concrete’s workability and depth of the concrete member. According to the Portland Cement Association, an insertion time of 5 to 15 seconds will usually provide adequate consolidation. Another general rule of thumb is to allow the vibrator to sink under its own weight and then remove the vibrator at a rate of about 3 seconds per vertical foot (300 mm). Concrete should move to fill the hole left by the vibrator; otherwise briefly reinserting the vibrator nearby should solve the problem. The vibrator should then be reinserted close enough to the last location so that the radius of action overlaps the last one.
Employees should familiarize themselves with each vibrator and mix design used at the plant. Changes in the surface appearance of the concrete and the sound or feel of the vibrator are often good indications that the concrete has been adequately consolidated. Large air bubbles should stop rising to the surface as large aggregate particles embed themselves into the concrete, and a thin film of mortar (sheen) should appear on the surface. According to the American Concrete Institute, the pitch or tone of an internal vibrator will typically decrease when the vibrator is initially inserted into the concrete, because the frequency will be reduced. The frequency will then increase slightly then level off when the concrete is free of entrapped air. Vibrator operators should become familiar with these simple indicators.
Vibrator operators should also be conscious of heavily reinforced areas and the location of large block outs, which may require increased vibration times. Noting the quality of formed surfaces and defects during a post-pour inspection are important steps in determining if the proper vibration equipment and procedures have been followed.
Formed surfaces should be relatively free of bug holes and honeycombed areas. The presence of sand streaks, caused by heavy bleeding and mortar loss, and crazing, caused by drying shrinkage cracking of the mortar, are often indications of excessive vibration, moving concrete with a vibrator and the use of an improperly sized vibrator.
Freshly placed concrete in wall and column forms behaves like a liquid producing hydrostatic pressure that acts laterally on the vertical faces of the formwork. However, due to concrete stiffening, the hydrostatic pressure is only temporary. As the fresh concrete changes from a liquid into a quasi-solid, the lateral pressure diminishes.
Common Issues & Corrective Actions
Assure that operators are properly trained in vibrating concrete
Concrete placement & vibration personnel should be experience and be a consistent placement team.
Areas where congestive steel are located require special attention to vibration detail and the work should be closely monitored by project engineer.
Reinforced rebar placement
Getting it in the right place and keeping it there during concrete placement is critical to the structure’s performance. Reinforcement should be placed as shown on the placing drawings. The drawings details will indicate the number of bars, bar lengths, bends, and positions.
Cover
One important reason for placing the reinforcing steel properly is to achieve the right amount of concrete cover that is the amount of concrete between the reinforcing steel and the surface of the concrete member. Cover is the single most important factor in protecting reinforcing steel from corrosion. Cover is also necessary to assure that the steel bonds to the concrete well enough to develop its strength. The requirements for minimum cover are usually listed in the project specifications or shown on the drawings.
Positioning
What’s important to remember is that the design of the structure is based on having the steel in the right place. Incorrect reinforcing steel placement can and has led to serious concrete structural failures. For example, lowering the top bars or raising the bottom bars by ½ inch more than that specified in a 6-inch-deep slab could reduce its load-carrying capacity by 20%.
You must use reinforcing bar supports, which are made of steel wire, precast concrete, or plastic. Chairs and supports are available in various heights to support specific reinforcing bar sizes and positions. In general, plastic accessories are less expensive than metal supports. The Concrete Reinforcing Steel Institute’s Ready Reference Reinforcing Steel Resource Guide or the classic Placing Reinforcing Bars has three tables that show most of the currently available supports in the various materials and describing the situation where each is most effectively used.
Simply placing the bars on supports is not enough. Reinforcing steel must be secured to prevent displacement during construction activities and concrete placement. This is usually accomplished with tie wire. The wire is typically 16½– or 16-gauge black, soft, annealed wire, although heavier reinforcement may require 15- or 14-gauge wire to hold the proper position of the rebar. A variety of tie types (ties are basically wire twists for connecting intersecting bars), from snap ties to saddle ties, are used in the concrete reinforcing industry.
For tying epoxy-coated bars it is recommended to use PVC ties (available from American Wire Tie). Proprietary Snap-On ties are also available, such as the Speed-Clip Rebar Tie from Con-Tie Inc. This is a simple device that attaches rebar in parallel or at any angle by hand.
The tie contributes no strength to the structure, so more are necessary only when the steel might become displaced during concrete placement. Be sure to keep the ends of the tie wires away from the surface of the concrete where they could rust. For preassembled mats or reinforcing steel, tie enough intersections to make the assembly rigid enough for placing—typically every intersection around the outside and every other in the middle of the mat.
Bar Supports
The amount of concrete cover over the reinforcing bar is very important. If it’s constructed properly, the concrete protects the reinforcing bar. Bar supports are used to hold the reinforcing bar up off the formwork or the ground to attain the proper depth of cover. They range from as simple as plain concrete blocks to plastic chairs, to wire bar supports.
Common Issues & Corrective Actions
Validate the people positioning and tying the steel and ensure they have the proper training and experience to complete the work to design specifications
Detailed inspections of steel placement and rigidity of the steel prior to pour
Rework any steel placement that shifts during pour that does not maintain proper cover
Concrete Rework
Concrete rework is an expensive and time consuming job when building in remote locations. If the contractor is required to rework a large area, it will have a dramatic effect on schedule. Will cause personnel to fall behind in other scheduled work.
Common Issues & Corrective Actions
Adequate supervision of mix slumps, placement of concrete and vibrations method must be maintained
Project engineer should be engaged in every pour
Common Issues & Corrective Actions
An inconsistent labor pool is a large contributing factor to project rework issues and is the responsibility of the General Contractor to correct. It is also a large factor in schedule slip.
Lack of consistent worker pool
Require contractor to maintain a consistent experienced labor pool
Require contractor to validate and demonstrate to the space fence management that replacement personnel are properly trained in the jobs they are performing
Require contractor to maintain records of all personnel training and performance for the jobs they are assigned
Closely monitor general contractor records to ensure experienced personnel are hired
Put the contractor on written notice and back charge contractor when inexperienced personnel are identified.
A strong experience construction manager is there to facilitate the construction process, work with the contractor to close any gaps in the construction details, answer RIFs promptly and enforce some basic rules given to the contractor at the first kickoff meeting to set the tone of the relationship from day one.
Continuous documenting of work from day one to serve as reference in the event Owner is forced to take legal action against the contractor for under performance.
Contractor must always be truthful and forthcoming with information
Misrepresentation and/or dishonest acts would be grounds for dismissal & replacement
Bad news does not get better with age – all issues need to be reported to Owner management immediately upon recognizing the problem by contractor
Inform the contractor we are here to perform this job as efficiently and professionally as possible in the best interest of the client.
When it has to be done right, hit the Expert Button
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
What is Stormwater Piping and How can it Affect a Construction Site?
Most storm sewer piping and stormwater piping flows by gravity, no pumps create pressure. The storm water drops into the system by inlets or roof drains then flows downhill. Obviously, the grade of the pipe matters. A low spot, or belly, in the pipe makes a trap, while a high spot, or hump, creates a dam. So the pipe crew needs to keep the pipe inverts (the lowest spot in the pipe where the water flows) installed in a straight line, at the slope required on the site drawings.
While the storm sewer piping rarely appears on the critical path of a project schedule, it’s surprising how many times the storm sewer installation becomes a problem and delays a project. Some of the common issues that occur with storm sewer piping are:
Unexpected rock or obstacle excavation.
Existing pipes in the way, discovered only during the installation.
Design errors that only become apparent during the installation.
Because of these type problems, a company like Nationwide Consulting, LLC can head off problems that may arise in the site development process and pay special attention to the storm piping and other underground infrastructure. The goal for the pipe work should be a speedy installation that surpasses the specification requirements (i.e. leakage, line, grade, backfill, etc.). Even if the pipe work is subcontracted, it is detrimental to the project to allow unacceptable pipe work to continue. If the pipe work has to be dug-up and redone at a later date, many other trades will be adversely affected.
Nationwide Consulting, LLC can inspect every item of work on the project if necessary. From our experience, one can predict the final quality (or acceptability) of pipe work by how the pipe foremen organizes the work. If the transit is set-up, the backhoe always digging, trenches are straight, and the pipe fitters are working methodically, the pipe work will typically be successful. On the other hand, a disorganized foreman and crew that appear to start and stop and constantly change methods are headed for trouble. At Nationwide Consulting, LLC we are aware of how the underground pipe works progresses and we try to head-off quality problems early. This type of qualified and experienced supervision can save days or in some case weeks of time and labor in the long run.
It’s also important to have a basic understanding of the common pipe types. Most projects we see these days use High Density Polyethylene (HDPE) pipe. There are lots of variations of HDPE available, and we have worked with most of them. Sometimes concrete pipe still comes through as the best choice, due to its strength and durability. Corrugated metal pipe (CMP) may also be used in some site plans; we have worked with everything over the years at Nationwide Consulting, LLC.
The degree to which storm sewer or stormwater pipe must be water-tight is normally made clear in the project specifications. Sometimes, a bit of water leakage from storm sewer piping is acceptable (often a trade off for lower cost and easier installation) and other times the storm sewer piping must be water-tight under a low pressure.
The most important thing to remember about your site and its stormwater piping, is to have an experienced professional firm handle it cost effectively. At Nationwide Consulting, LLC, we are proud to say, we are that firm, we handle all aspects of developing your full construction project from site to finished structure, to spec efficiently, cost effectively and on time.
When it has to be done right, hit the Expert Button, call Nationwide Consulting, LLC
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
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What can Nationwide Consulting, LLC teach you about Earthwork Excavation and Compaction?
Earth excavation and grading can be a fascinating part of a construction project. The powerful heavy equipment, used to best advantage by a skilled operator, is a joy to behold. The scope of the excavation job varies from digging footings for a small building to moving millions of cubic yards of earth. The one thing all excavation jobs have in common, though, is that careful planning is the key to success.
There are several terms which should be defined. Excavation is often used as a broad term which includes cut (or excavation) and fills (or embankment). Cut is defined as removing material to lower the elevation of an area. Fill is defined as placing material to raise the elevation of an area. Compaction must take place during a fill operation to increase the density of the soil material being placed. Another common breakdown in excavation work is bulk excavation and trench excavation.
Swell and shrinkage are two important, and often misunderstood, terms. Consider the simple example of digging a 1.0 cubic yard hole with a shovel and throwing the dirt into wheelbarrows. In the ground the 1.0 cubic yard of soil is in its virgin (or natural) state. Upon being shoveled into the wheelbarrows the soil is in a loose (or lower density) state and probably has a volume of 1.2 to 1.4 cubic yards. This process of soil increasing in volume from its virgin state to a loose state is called swell.
Shrinkage, on the other hand, occurs when that same soil is placed back in the one cubic yard hole and is properly compacted. Depending on the soil type, the final volume could be 0.9 cubic yards or 1.1 cubic yards. The above explains why when one digs and refills a hole, sometimes there is not enough soil to fill the hole and sometimes there is soil left over.
An excellent table showing weights, swell factors, and shrinkage factors for various materials is included below. The table of characteristics is a growing body of knowledge with many contributors over the past 100 years. All the values given are necessarily approximate. The rock materials are labeled in the following way: I, igneous; S, sedimentary; or M, metamorphic. The cubic yard in cut column assumes natural moisture and has + 10 percent variation. The cubic yard loose column has a +33 percent variation. For example, damp clay with a given swell of 40 percent should be assumed to have a swell range of 30 percent to 53.2 percent. The cubic yard in fill column also has a 33 percent variation and assumes mechanical compaction at appropriate moisture levels.
In earth excavation and site grading some of the most common problems encountered are improper compaction, incorrect final elevations, and working beyond the specified area to be disturbed. There are no magic, simple answers or procedures to make the above problems not happen.
Improper soil compaction is a common and often difficult problem. Soil Engineering and Geology, a previous section, discusses the technical aspects of soil compaction. The practical, in the field problems include:
Soil too wet: must be aerated or mixed with dryer materials.
Soil to dry: must add water
Soil lifts for compaction too deep: lessen lift depth
Different types of soil: check if the proctor test (the test which measures the density of the soil sample for other tests to be measured against) matches the type of soil encountered
The soils inspector holds-up the compaction operations to takes tests: try to create a team environment and plan test taking for everyone’s advantage.
The problems of incorrect final elevations and working beyond the specified contract limits are more straight-forward. The excavation contractor certainly should be responsible for their own work, the only real problem involves determining the mistake. The site developer should be aware of this potential problem and develop his own solution to resolve it.
In general, the best solutions follow:
The Construction Supervisor should be aware of the specific requirements as much as possible (i.e. understand the whole job) and spot check on occasions.
Whenever practical the subcontractors following the site grading should check and accept the previous work prior to beginning.
Even though the excavation contractor is ultimately responsible for their work, project schedule or quality can be ruined if errors are found too late. The above are some problems encountered in the field with possible solutions. In many cases the solutions seem simple to apply but are quite difficult and costly. Regardless of the complexity, the site work is almost always critical to the timely completion of the project and must be a priority for the Site Supervisor, like Nationwide Consulting, LLC. It is important to have the experience that stretches over vast numbers of projects in the same area to fully understand and overcome possible outcomes.
When you have a construction project that involves earthwork, Hit the Expert Button; call Nationwide Consulting, LLC
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
How Green Demolition Works in Several Ways to Benefit Your Business and Your Community
Nationwide Consulting, LLC encourages Green Demolition for several reasons. First, it is good for the environment and good for your community. Second, it reduces the large amount of land fill waste by encouraging the 3 Rs – Reduce, Reuse and Recycle. Third, it turns what could be a public relations problem into a public relations boon. Often, there are community attachments to structures scheduled for demolition, with Green Demolition, the demolition becomes a re-birth of sorts.
The United States generated an estimated 136 million tons of construction waste in 2014 according to the Environmental Protection Agency. This accounts for up to 40 percent of the country’s solid waste [source: Whole Building Design Guide]. Green Demolition or deconstruction is the dismantling of a building so that as many of its elements as possible (usually around 80 percent) can be recycled or reused rather than going to landfills and subsequently polluting the Earth’s soil and water.
Green demolition is now mandatory in some cities, such as San Diego, California. Developers will only get their permit deposits refunded if they prove that 50 percent or more of their construction waste was reused or recycled. Some states have waste facilities that will accept construction waste in bulk for a higher fee while others require the materials to be separated before they can be processed.
Recycling is a costly process, which is why it’s the last of Nationwide Consulting, LLC’s “three Rs” – reduce, reuse and recycle. Reducing requires advanced planning because it involves paying attention to the dimensions of the materials you’ll need so you can get by without throwing out too much excess. This is especially true with cardboard, drywall and wood, the three most used construction materials. Reusing might be the most important of the three. All of the following materials can be reused in later projects if harvested properly:
Wood floors and beams
Windows and doors
Fixtures and appliances
Tiles and carpeting
Aluminum siding
Roofing materials
Pipes
Bricks
Green demolition takes time and also costs more per job initially than traditional demolition; but you can save money on landfill charges and also get tax credits if you donate some of the materials. If the event is used properly by the public relations department, the value in good will can be enormous. In addition, if you want your company to be LEED certified according to the United States Green Building Council standards, you’ll need to use green demolition, something Nationwide Consulting, LLC can help you with from start to finish.
Considerations During Green Demolition
Reusing and recycling construction and demolition waste is the “environmentally friendly” thing to do, and could also result in cost savings while promoting local entrepreneurial activities. A waste reduction plan, clearly outlined in the project’s specifications, would require the following:
Specification of waste-reducing construction practices.
Reuse of construction waste (or demolition) material on the construction site (for instance, concrete can be ground up to use for road aggregate).
Salvage of construction and demolition waste for resale or donation.
Return of unused construction material to vendors for credit.
Delivery of waste materials to recycling sites for remanufacture into new products.
Tracking and reporting all of this activity.
It is critical to note that reusing, salvaging, and/or recycling materials require additional up-front planning. The contractor must have staging/storage locations and must allot additional time for sorting materials, finding buyers or recycling centers, and delivering the materials to various locations.
Remember if you have a project coming up next year, now is the time to call Nationwide Consulting, LLC for help and advice. We can take your project from raw acreage to finished site as effortlessly as making that call to Nationwide, call us now, We can help:
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
At Nationwide Consulting, LLC we understand the needs of the office complex developer, efficiency and cost effectiveness. One of the most important facilities of an office building is the parking facilities. Now we concentrate on commercial parking lot design and how to best serve both the developer and the eventual tenants and visitors of the facility, efficiently and cost effectively.
The ease in which the customers can find a parking space near the office they are looking for is very important, in order to make that office complex a favorite destination. It is equally important that the visitors be able to find their way back to their car easily, and exit the office complex without incident.
Walking from the Space to the Offices:
Once the office worker or visitor has safely gotten his or her car into the best available space, he or she has only to walk to the office destination. We have been assuming that parking would be laid out around the outside of the office building, with the interior of the Commercial Parking Lot Design reserved for pedestrian movement.
Some parking lots have concrete sidewalks between the rows of parked cars. If they are installed, they should be at least 7 feet wide to allow for the overhang of the front ends of the cars, and to allow room for two people carrying files or equipment to pass each other without difficulty.
An office building, which is served by a multi-story self-parking structure, is able to boast that no tenant or visitor need walk more than 110 feet from his parked car without being under some cover. Covered walkways for office workers and visitors can be an important feature, especially where the parking is spread out considerably, and the weather often inclement.
Multi-story parking garages, because of the relatively high cost per parking space, are not usually recommended by Commercial Parking Lot Design, except where the amount of land is limited and its cost per square foot is high.
For office complex purposes, it is almost necessary that the structure be a self-service parking garage, and this fact raises some problems of design in a multi-level garage, particularly in the size of the spaces and aisles on each floor, and the width and design of the ramps leading to the floors and elevators.
Can you have too much parking?
We know of no existing office building that has too much parking. It is true some parking spaces are not economically used, due to their distant location from the offices. The poorly located spaces would be used more frequently if they were more conveniently located. The limit on parking area is for the most part determined by the distance that people have to walk to get from their cars to the offices.
In an office complex which offers only an uncomfortable walk through a sea of parked cars, the limit that people can reasonably be expected to walk is about 350 feet. On the other hand, if you can offer the tenant or visitor something other than cars to look at, he will most likely walk further. Arcades with meaningful statuary and interesting displays, or pleasantly landscaped areas to walk through might permit the extension of the parking area in commercial parking lot design.
Nationwide Consulting, LLC has handled over 400 million dollars worth of office building and manufacturing facilities development projects all over the world. Unique challenges can come up in the office complex parking lot design process, and Nationwide is uniquely qualified to handle any challenge.
Whether it is land clearance, demolition of existing structures, parking lot coverings, curbs, access roads, infrastructure, or the building itself, Nationwide Consulting, LLC is the go to firm for results. Put your projects site development supervision needs in our hands and be assured the job will be done, efficiently and in a cost effective manner.
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
Call Nationwide Consulting, LLC today for a free consultation and you hit the expert button:
