SCS Engineers is a proud supporter of the SWANA Evergreen Chapter. the Chapter offers an annual scholarship to qualified undergraduate and graduate students in honor of Deborah Lambert. Ms Lambert was the SWANA Evergreen Chapter President 2002-2005, and we honor her for the many years she dedicated to the solid waste management field.
Please join us for our Winterfest Annual Holiday Party, which will be held today from 4:30 to 8:30 PM at the Bellevue Club, 11200 SE 6th Street, Bellevue, WA 98004. Enjoy fabulous food with friends and colleagues at the beautiful and festive Bellevue Club, the perfect way to start the holiday season! In addition to being a fun holiday event, Winterfest is our primary fundraising opportunity for our Educational Scholarship Fund.
Bellevue Club
11200 SE 6th Street
Olympic Suite A
Bellevue, WA 98004
High-density polyethylene pipes have been used for landfill leachate collection and conveyance lines for several decades because of the chemical compatibility of HDPE material with many different types of liquids and chemicals. Designing a leachate collection system for a landfill disposal cell involves numerous engineering analyses of different components involved in collecting and conveying leachate. One of the important engineering evaluations is a determination of structural stability of HDPE leachate collection pipes at the bottom of the landfill.
Structural Stability of HDPE Pipe
Modern landfills are gradually becoming larger and deeper; deeper landfills will naturally impose a higher surcharge loading on the HDPE leachate collection pipes below the waste column. Engineering methodologies for the structural stability evaluation of HDPE pipes with significant surcharge loading have been around as long as HDPE pipes have been in production.
There are three criteria used when evaluating the structural stability of HDPE pipes; wall crushing, wall buckling, and ring deflection. Wall crushing can occur when the stress in the pipe wall, due to external vertical pressure, exceeds the compressive strength of the pipe material. Wall buckling, a longitudinal wrinkling in the pipe wall, can occur when the external vertical pressure exceeds the critical buckling pressure of the pipe. Ring deflection is the change in vertical diameter of the pipe as the pipe deforms under the external pressure. Empirical formulas by HDPE pipe manufacturers or researchers are available to check each criterion.
SDR 11 vs. SDR 17 HDPE Pipe
When a structural stability evaluation involves high surcharge loading on the pipe, an engineer may automatically select SDR 11 HDPE pipe without going through an evaluation process. The engineer’s reasoning is that the higher wall thickness of SDR 11 pipe, as compared to SDR 17 pipe, is the logical choice because it provides a higher level of structural stability to the pipe. In the case of wall bucking and wall crushing, where the pipe strength in these two criteria is inversely proportional to the SDR value, the engineer is making the right choice. The strength is greater for the lower SDR value that represents thicker pipe wall thickness; making SDR 11 stronger than SDR 17.
However, in the case of ring deflection, the pipe strength is not a function of SDR, but a function of another parameter called allowable ring deflection. The allowable ring deflection value varies from one SDR to another and is generally reported by pipe manufacturers. The allowable ring deflection for SDR 17 pipe is greater than all other SDR pipes, which makes SDR 17 pipe stronger when considering ring deflection. SDR 17 pipe is also the most commonly used HDPE pipe in the landfill industry, being lighter in weight per unit length of the pipe than SDR 11, thus making it less expensive than SDR 11 pipe.
Which Is Best For My Landfill?
SCS Engineers recommends that landfill engineers consider SDR 17 pipe as the first choice for use as a leachate collection pipe below the waste column, and then other SDRs if SDR 17 does not pass the three structural stability criteria mentioned above.
Read more blogs by Ali Khatami, click here and type “Advice from the Field” in the search box.
National Waste and Recycling Association is sponsoring a FREE 90-minute webinar on December 6 at 3:00 pm ET. The webinar is highlighting the programs, strategies, and best practices of their six 2017 Recycling Award Winners.
The recipients will describe their unique blend of technologies, outreach, and program management that made a difference in their communities. The audience will have a chance to ask questions and find out how to implement these innovative ideas into their own operations and businesses.
Agenda:
More Solid Waste Management resources and success stories here.
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
Most often, landfill gas system design is added to an existing landfill cell, but the co-authors of this article explain the benefits of considering the LFG system during the landfill bottom liner design process. Doing so during the early stages of the landfill’s life, make it possible to improve collection efficiencies, lower operating costs, and save time in the future.
Continue to the full article, Planning Ahead for the Bottom Liners, published in MSW Magazine’s November 2017 issue and learn about the co-authors from Sarasota County, Florida Public Utilities and SCS Engineers.
How to stay in compliance, do what is right and avoid costly fines and litigation.
The State of California passed regulations in 2015 that impact all craft brewers (SIC Code 2082) who must comply with these regulations by either preparing and implementing a plan or certifying “no exposure” for their facility. While enforcement has so far been limited, the State maintains a searchable database by SIC code, and compliance determinations by government officials, environmental groups and other non-government organizations is comparatively easy.
Based on our research, the current compliance rate for craft brewers in California is relatively low. Those who don’t comply run the risk of fines or citizen suits by non-profits, which can be costly and time-consuming. Find out about the different types of compliance, what is involved, and how to stay in compliance.
A Qualified Industrial Storm Water Practitioner (QISP) can help you answer the following questions:
For more information or help with stormwater compliance in California, contact Dan Johnson at or the California Craft Brewers Association. If you are a CCBA member, you may access slides from a recent Webinar relating to Stormwater Compliance for Craft Brewers here. To sign up for our e-newsletter on stormwater and compliance tips send an email to .
Contact for stormwater compliance services in all 50 states.
Material recovery facilities (MRFs) are seeing many challenges that directly impact operations. Some of these challenges include: new recycled material quality standards from China, the ratcheting up of voluntary and mandatory local and state recycling goals, lower tolerance for worker injury, increasing volumes and a changing waste stream, disposal bans on organics in landfills, and high demand from emerging energy
markets for organics.
MRFs equipped with the latest technologies are able to meet tightening standards for traditional quality recycled materials and some are also starting to provide a separate, clean organics stream for downstream alternative energy projects. Many MRF operators are now benefitting from these new technologies, with increased throughput and quality of end product.
The article by Bruce Clark and Mike Kalish of SCS, provides an overview of the latest developments in MRF processing equipment systems that are helping owners and operators meet these challenges and at the same time helping maintain a healthy bottom line.
Related articles, case studies, and services.
Ryan Joslyn
University of Central Florida, MS
Robert P. Stearns/SCS Engineers Master’s Scholar
Project: Field Investigation of an Elevated Temperature Florida Landfill
For reasons that are not entirely clear, incidents of elevated temperatures in municipal solid waste landfills are occurring at increasing frequency. These landfills present temperatures that well exceed the range tolerable for micro-organisms (~176°F). Given the significance of elevated temperatures at landfills and the growing number of landfills with these issues, the goal of Joslyn’s research is to develop a more complete understanding of elevated temperature landfills using landfill gas and leachate monitoring data, specifically in the state of Florida.
Robert P. Stearns, Chairman and CoFounder of SCS Engineers, joined the EREF Board of Directors in 1999 and served as Chairman from 2004–2005. At SCS, he directed or served in a review capacity on many of the firm’s solid waste management-related projects. In 2007 EREF awarded the first Robert P. Stearns/SCS Engineers Master’s Scholarship, which was established to expand EREF’s successful doctoral-level scholarship program.
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.
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