Using a simple example the authors make apparent the importance of understanding a refrigeration system’s actual performance. An energy balance is a very useful tool to do so.
Not only do PSM regulations require that facilities have this in your PSM program, there is real value in understanding a system’s capacities. Operation and efficiency translates to substantial dollar savings every year. Savings that can be reinvested in your facility.
Calculating the total consequences of an unbalance system is more complex, but there are considerable savings running a properly energy balanced refrigeration system. Savings that can fund maintenance needs and avoid postponing timely repairs.
This white paper, presented at the RETA 2017 Conference in Pennsylvania is available in English and Spanish by clicking here.
Learn more about environmental and engineering services for Process Safety Management (PSM), Risk Management Plans (RMP), and ammonia refrigeration safety at SCS Engineers.
Ann O’Brien of SCS Engineers has pulled together a list of questions that printers should be asking themselves before the environmental reporting season is upon us.
Use Ann’s questions as a guide to find out how ready your company is, and decrease your risk of non-compliance by being more organized.
If you don’t know the answers, ask Ann. She’s one of our air and water permitting, monitoring, and reporting experts at SCS. Ann specializes in printing industry compliance.
Contact and we’ll direct you to an air, storm water, wastewater, or groundwater expert near you and in your industry.
We continue SCS’s Advice from the Field blog series with guidance from an article in MSW Magazine by Daniel R. Cooper, Jason Timmons, and Stephanie Liptak.
The authors of a recent article in MSW Management Magazine present engineering ideas that provide for more efficient construction of a GCCS. Gas system operators will benefit by having fewer pumps to operate and maintain and shallower headers that are more easily accessible. Odor management will be easier along with other benefits.
Read the full article here to learn about the design elements for maximizing long-term benefits, impacting: bottom liners, location of the blower/flare station, leachate risers, extraction well targets, and external header piping.
It is challenging to restore properties with a past, but you can do it on time and on budget if you plan ahead to address contaminated historic fill. Follow these tips and use the brownfield redevelopment checklist to keep your next redevelopment on track.
Design Phase
Consider how contaminated historic fill impacts the following:
Site feature locations – You can reduce or even eliminate landfill disposal costs by carefully selecting locations for your building, underground parking, parking lot, utility, and green space.
Storm water infiltration – Do you know that storm water infiltration devices must be located in areas free of contaminated historic fill? Infiltration devices cannot be located where contaminants of concern (as defined in s. NR 720.03(2)) are present in the soil through which the infiltration will occur.
Subslab vapor mitigation system – Already know you have contaminated historic fill on site? Consider adding a subslab vapor mitigation system to the design of your new building. It is usually much cheaper to install this system in a new building than to retrofit one into an existing building. It can also mitigate radon gas.
Planning & Design
Determine if contamination requires the following plans to manage the construction phase:
Material management plan – It establishes how you will separate excavated contaminated material from material that is not contaminated. It also outlines how you will handle contaminated material, either by disposing of it off site in a landfill or reusing it on site in an approved area such as a paved parking lot. This plan also covers screening, sampling, and testing contaminated materials, if required.
Dewatering plan – If the development requires excavation through contaminated historic fill to depths below groundwater, you will need a dewatering plan to properly manage discharge of the water. You may be able to discharge the water to the storm sewer or the sanitary sewer depending on the type and concentration of contaminants. You must determine local and state permit requirements before implementing your dewatering plan.
Demolition plan – The demolition plan for removing existing structures during redevelopment should include handling, removal, and disposal of potential contaminants such as lead and asbestos. The demolition plan should also address recycling and reuse of existing on site materials like concrete. You may be able to save money by crushing and reusing concrete on site as fill material, or by hauling and crushing it off site to reuse it as fill at another property. This approach can save you considerable money compared to landfill disposal.
Ready to start saving time and money addressing contaminated historic fill at your next redevelopment? Contact Ray Tierney for help evaluating your options in the Upper Midwest, or using the SCS Brownfield Redevelopment Checklist .
Live in another part of the country? SCS Engineers offers brownfields, remediation, due diligence, and all appropriate inquires services nationwide. Contact us today at .
Learn more about these services at SCS Engineers; read our case studies and articles:
Brownfields and Remediation
Due Diligence and All Appropriate Inquiries
Temporary Landfill Caps
Temporarily capping landfill slopes is becoming a common measure for landfill operators. There are many benefits to closing landfill slopes with geomembrane on a temporary basis. One of the benefits is delaying construction of the final cover. Following is a discussion of the steps that should be taken to determine whether temporarily capping the slope with geomembrane and postponing the final cover construction is a better financial/operational decision.
Cost Burden
Constructing the final cover is costly, and it is considered an unavoidable expense that has no return on the money spent. Therefore, some operators perform a financial evaluation to determine whether the final cover construction costs can be delayed (provided, of course, that such delays are acceptable to the regulating agency). When evaluating whether to delay the final cover, the cost of maintaining the slopes during the postponement period should be considered. The operator must look at the financial aspects of either closing the slopes with a temporary geomembrane or of leaving the slopes open during the postponement period.
Temporary Landfill Capping Option
The benefits of temporarily capping the slopes during the postponement period may include:
The other side of the coin is the expense associated with the temporary cap. There may be repair costs associated with the geomembrane every few years in order to ensure that the temporary cap remains intact.
Leaving Slopes Open Option
The option of leaving the slopes open during the postponement period involves maintenance expenses such as:
The benefits of leaving the slopes open are twofold: first, the operator will save the costs of constructing the temporary cap; and second, the operator will gain additional airspace as waste settles during the postponement period.
Experience with the Temporary Capping Option
As discussed above, both options provide the benefit of gaining additional airspace during the postponement period. Constructing a temporary cap involves the costs of materials and installation, including the geomembrane and the ballasting system that keeps the geomembrane in place. Generally, the financial and non-tangible benefits of a temporary cap that remains in place five years or longer are more attractive than leaving the slopes open; therefore, most operators choose to install a temporary cap. The next step in the financial evaluation should be comparing the costs of the temporary cap to permanently closing the slopes without postponement.
Final Step in the Financial Evaluation
The next question is whether it makes financial sense to postpone the construction of the final cover.
Waste settlement during the postponement period and the resulting airspace are considered the determining financial factor in choosing the right option. If the present worth value of the airspace generated from waste settlement during the postponement period is greater than the cost to construct the temporary cap at the present time, then the temporary cap option would make financial sense; otherwise, the final cover should be constructed without postponement.
It should be noted that the length of the postponement period plays a very important role in this financial equation. Longer postponement periods have the potential for a greater gain in airspace. Another incentive that should be factored into the financial evaluation is the potential return on the money set aside for the final cover construction during the postponement period.
To assist with this financial evaluation, landfill operators are encouraged to discuss these options with their landfill engineers. Settlement models can be performed to calculate the amount of airspace that may be generated during the postponement period as well as the present worth value of the generated airspace. The returns on the final cover construction costs during the postponement will just be “icing on the cake.”
Read the related Advice From the Field blogs from the landfill and LFG experts at SCS Engineers:
Contact the author: Ali Khatami or your local SCS Engineers’ office.
Typical Conditions
The organic matter that is placed in landfills goes through a decomposition process that is exothermic and releases heat inside the landfill space. There are also other exothermic processes such as metal corrosion, hydration, carbonation, and acid-base neutralization that contribute to the heat generation phenomenon in landfills. Municipal solid waste has a relatively low heat conductivity characteristic, which means the heat is not as easily conducted through the waste keeping the landfill interior generally warmer than the areas near the landfill exterior.
Landfills expel the heat in different ways; propagating through the waste mass to the air, ground, leachate, and gas heat sinks. The heat escapes the landfill at its boundaries by convection to the air above the landfill surface and by conduction to the ground below the waste. Heat can also escape from landfills through liquids and gases removed from the landfill. For example, by conduction, via leachate that flows through the waste and is removed by leachate sumps and by convection, and via gases generated inside the landfill that are removed through the gas collection system.
Special Conditions
The large majority of landfills in the country show no signs of special conditions indicating too much heat. The characteristics noted in this blog have been observed in a few large, deep, wet landfills. Field investigations at landfills with high temperatures revealed that the highest temperatures are generally located at mid-point to the two-thirds depth of waste from the top surface. Temperatures as high as 250 °F have been recorded by specialized measuring devices.
Under certain conditions, elevated temperatures may occur inside a landfill, and the excess heat changes the character of chemical reactions taking place in the landfill, such as the decomposition process of the organic matter. Other documented changes that may take place in accumulated heat conditions are: leachate becoming stronger with higher BOD, lower pH, higher carboxylic acids and salts; concentrations of certain acids increasing; carbon dioxide and carbon monoxide generation increasing; the ratio of methane to carbon dioxide decreasing; hydrogen generation increasing; landfill odors changing to a significantly pungent character; landfill settlement rates increasing; gas generation and gas pressure increasing; leachate generation increasing; along with other changes.
Research
Heat generation in landfills is studied by researchers, reported in technical literature and scientific papers by academia and the industry. A summary of the findings related to the amount of heat generated from municipal solid waste in landfills is presented in Table 1 of Heat Generation in Municipal Solid Waste Landfills posted on the California Polytechnic State University, Robert E. Kennedy Library website.
Since the issue of high temperatures in landfills is of extreme importance to landfill operators with respect to compliance, operations, and financial aspects of these cases, finding out the cause and sources of excess heat is a hot subject in the field of landfill science. The largest research grant supporting the on-going research in this field was awarded by the Environmental Research & Education Foundation (EREF) in December 2014. So far, three parts of a technical article explaining chemical mechanisms through which organic matter decomposes and generate various types of other chemicals and heat have been published by the researchers of the above grant in Waste360. The research is on-going, and more information will be published in future. Links to the first three parts of the above article are provided here:
Prevention, Diagnosing and Managing ETLFs
SCS was involved in the preparation of standards for large, deep and wet landfills for a major waste operator in 2016. The intent of the standards is to implement measures to prevent elevated temperature conditions in large, deep, and wet landfills. SCS’s experience at such landfills and its in-depth knowledge can be valuable to those waste operators who are either experiencing elevated temperature conditions in their landfills or want to prevent conditions forming in their landfills proactively.
About the Author: Dr. Ali Khatami
Join SCS Engineers at the Global Waste Management Symposium to learn more, or click these links read about our landfill and landfill gas to energy services, clients, and articles.
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Discovering unexpected pockets of soft soils at the time of construction can delay your project and drive up costs for landfills, support features, and many other types of construction. If you don’t find them, building over them can result in unexpected settlement affecting a structure or building, or cause a slope stability problem for a berm or stockpile. You can avoid both of these scenarios with early investigation and appropriate construction planning.
While landfill development investigations typically require numerous soil borings within the proposed waste limits of the landfill, it’s common to overlook perimeter areas. Pockets of soft soil deposits can be associated with nearby existing wetlands, lakes, or rivers; with wind-blown silt or ancient lake deposits from periods of glaciation; or with fill placed during previous site uses.
The landfill perimeter areas may contain tanks for leachate or fuel, buildings, perimeter berms for screening or landscaping, stockpiles, and other features. A tank or building constructed over soft soils could experience unexpected settlement affecting the performance and value of the structure. The potential for a slope stability problem can increase for a large berm or stockpile built on soft soils.
The first step to avoid these problems and identify problem soils is to include perimeter areas in your subsurface investigation. Perform soil borings or test pit excavations at the locations of the proposed perimeter features such as tanks or berms. If you encounter soft soils, address them like this:
Contact SCS’s geotechnical engineers for more information on how to find and test soft soil areas early in a landfill’s project schedule, so you can effectively address associated construction issues in a way that considers cost and minimizes unexpected project delays.
These grants often target rural areas that don’t necessarily have the support needed to catch up in today’s world of rapid technological advances. A quick Google search shows that at the national level, the USDA offers a Solid Waste Management Grant which may be applied to the cost of program improvements such as landfill evaluations, technical assistance, or training. For this particular grant, any local government, academic institution, or nonprofit servicing an area with fewer than 10,000 people may apply.
This type of funding presents an opportunity for SCS to help address clients’ financial burdens. Awareness of the grants available is a common obstacle, but with some region-specific research, potential project identification, guidance and assistance with grant funding SCS can enhance your arsenal of services.
Here are some places to look for funding:
Contact the authors if you have questions: Ryan Duckett and Quinn Albertson, we’re always happy to help.
Pat Sullivan discusses two case studies that provide examples of two different approaches to odor management. The proactive approach resulted in a more positive outcome than the reactive approach. Although the odor issues never go away completely, the proactive facility has avoided lawsuits and regulatory enforcement and continues to have a positive working relationship with the community.
SCS Engineers freely shares our articles and white papers without imposing on your privacy.
Click to read Part I of this two part series. We’ll let you know when Part II is published soon.
Tuesday, October 10, 1:00 pm – 2:30 pm ET
This Air & Waste Management Association webinar covers the effective, sustainable operation of municipal solid waste (MSW) landfills in today’s changing environment.
The latest updates to EPA regulations in over two decades limiting air emissions from landfills will be reviewed in detail.
Participants will learn the available models for quantifying landfill gas generation emissions and which model to use in different situations as well as energy recovery from landfill gas, its emissions, and how control requirements can affect feasibility.
