Need for a standardized approach to characterizing, permitting, and constructing landfills in karst geologic settings

Citation
Need for a standardized approach to characterizing, permitting, and constructing landfills in karst geologic settings

Material Information

Title:
Need for a standardized approach to characterizing, permitting, and constructing landfills in karst geologic settings
Alternate Title:
NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst
Creator:
Bachus, Robert C.
Tedder, Richard B.
Publisher:
University of South Florida
Publication Date:
Language:
English

Subjects

Genre:
Conference Proceeding
serial ( sobekcm )

Notes

General Note:
pg(s) 61-69 The challenges presented by geohazards play a significant role in the permitting of environmental facilities, particularly those situated in karst geologic settings. With regards to landfills, and specifically to municipal solid waste (MSW) landfills, regulators have a significant responsibility to protect the environment and must make decisions regarding the siting and permitting of these facilities. While these decisions are based on their objective assessment of site-specific characterization information, their decisions are often scrutinized by the public and by the owner/permittee…entities that often (and usually) have contrasting interpretations of the same site characterization information. The Florida Department of Environmental Protection (FDEP) has initiated an innovative approach to help the agency in the decision-making process by convening a Technical Advisory Group (TAG), comprised of several agency- and industry-recognized experts who are experienced in the investigation, characterization, permitting, and construction of engineered facilities in karst settings. Through a process involving the compilation and assessment of various site-specific factors, the TAG is working with FDEP personnel to develop specific and objective guidelines that can be used by owners, permitees, consultants, and the agency in developing investigation, characterization, design, construction, operations, and monitoring strategies for facilities overlying karst geologic conditions. The activities of FDEP and its TAG are actively reviewed by the public, who have also been requested by FDEP to participate in the process of developing these guidelines. The objectives for making this presentation are twofold, specifically to provide information to and then solicit information from the conference participants (and readers). The approach being taken by FDEP and the TAG focuses on technical issues regarding the investigation, characterization, design, and construction of engineered facilities in karst geologic settings. The authors recognize that these technical issues impact all engineered facilities, not just those constructed for environmental applications. Therefore, the approach developed by FDEP may benefit other agencies, owners, and consultants who face similar challenges. The participants at this conference likely have specific experiences and can offer recommendations that will ultimately be beneficial to the DEP and the TAG. In this presentation, the authors will actively engage the participants and will request input based of their experience and expertise.
Restriction:
Open Access - Permission by Publisher
General Note:
See Extended description for more information.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
K26-02234 ( USFLDC DOI )
k26.2234 ( USFLDC Handle )
11807 ( karstportal - original NodeID )

Related Items

Related Item:
Click here to view/download linked file

USFLDC Membership

Aggregations:
Added automatically
Karst Information Portal

Postcard Information

Format:
serial

Downloads

This item has the following downloads:


Full Text
Description
pg(s) 61-69 The
challenges presented by geohazards play a significant role in
the permitting of environmental facilities, particularly those
situated in karst geologic settings. With regards to landfills,
and specifically to municipal solid waste (MSW) landfills,
regulators have a significant responsibility to protect the
environment and must make decisions regarding the siting and
permitting of these facilities. While these decisions are based
on their objective assessment of site-specific characterization
information, their decisions are often scrutinized by the
public and by the owner/permitteeentities that often (and
usually) have contrasting interpretations of the same site
characterization information. The Florida Department of
Environmental Protection (FDEP) has initiated an innovative
approach to help the agency in the decision-making process by
convening a Technical Advisory Group (TAG), comprised of
several agency- and industry-recognized experts who are
experienced in the investigation, characterization, permitting,
and construction of engineered facilities in karst settings.
Through a process involving the compilation and assessment of
various site-specific factors, the TAG is working with FDEP
personnel to develop specific and objective guidelines that can
be used by owners, permitees, consultants, and the agency in
developing investigation, characterization, design,
construction, operations, and monitoring strategies for
facilities overlying karst geologic conditions. The activities
of FDEP and its TAG are actively reviewed by the public, who
have also been requested by FDEP to participate in the process
of developing these guidelines. The objectives for making this
presentation are twofold, specifically to provide information
to and then solicit information from the conference
participants (and readers). The approach being taken by FDEP
and the TAG focuses on technical issues regarding the
investigation, characterization, design, and construction of
engineered facilities in karst geologic settings. The authors
recognize that these technical issues impact all engineered
facilities, not just those constructed for environmental
applications. Therefore, the approach developed by FDEP may
benefit other agencies, owners, and consultants who face
similar challenges. The participants at this conference likely
have specific experiences and can offer recommendations that
will ultimately be beneficial to the DEP and the TAG. In this
presentation, the authors will actively engage the participants
and will request input based of their experience and
expertise.



PAGE 1

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 61 issues regarding the investigation, characterization, design, and construction of engineered facilities in karst geologic settings. The authors recognize that these technical issues impact all engineered facilities, not other agencies, owners, and consultants who face similar challenges. The participants at this conference likely have In this presentation, the authors will actively engage the participants and will request input based of their experience and expertise. Introduction It is often said that we can only be certain of two things professionals can safely add three more relative certainties: (i) as a society we continue to generate large amounts of garbage (i.e., MSW) that require safe and (iii) geohazards that restrict the location of these performance, there is a reticence of the populace to view this as a societal need and prefer that the problem be shifted to others at other locations. Regarding geohazards Florida, which is one of the most populated states in the country. Across Florida, and particularly in Central Florida where the karst is prevalent and the population societal need runs headlong into geologic constraints. NEED FOR A STANDARDIZED APPROACH TO LANDFILLS IN KARST GEOLOGIC SETTINGS Robert C. Bachus, Ph.D., P.E., D.GE. Geosyntec Consultants, 1255 Roberts Blvd. NW, Ste. 200, Kennesaw, Georgia 30144 USA, rbachus@geosyntec.com Richard B. Tedder, P.E. Florida Dept. of Environmental Protection, 2600 Blair Stone Rd., MS 4565, Tallahassee, Florida 32399 USA, Abstract The challenges presented by geohazards play a facilities, particularly those situated in karst geologic must make decisions regarding the siting and permitting of these facilities. While these decisions are based on their information, their decisions are often scrutinized by often (and usually) have contrasting interpretations of the same site characterization information. The Florida Department of Environmental Protection (FDEP) has initiated an innovative approach to help the agency in in the investigation, characterization, permitting, and construction of engineered facilities in karst settings. Through a process involving the compilation and permitees, consultants, and the agency in developing investigation, characterization, design, construction, operations, and monitoring strategies for facilities overlying karst geologic conditions. The activities of who have also been requested by FDEP to participate in provide information to and then solicit information from the conference participants (and readers). The approach

PAGE 2

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 62 In anticipation of the collision course, the Florida Department of Environmental Protection (FDEP) has taken a proactive course of action to develop technically rigorous recommendations regarding the siting, permitting, design, construction, operations, and monitoring of MSW facilities in the State that need to be located over karst terrain. This paper will identify geotechnical, water resources, and geoenvironmental professionals who must deal with the often competing demands placed by society in dealing with the disposal of MSW and the locations of the disposal facilities. proactive strategy for addressing the waste disposal problems caused by the challenging geologic conditions, in Florida. Finally, the authors will solicit opinions and experiences from the participants of the conference regarding improvements to this initiative, recognizing that do nothing or take the waste elsewhere is not a sustainable alternative. Before a strategy can be developed, a sense for the magnitude of the problem needs to be recognized. In Florida (as well as in many parts of the country), the problem prevalence of karst in the underlying geologic formations. A brief summary of these problems follows. Regarding solid waste practices and experiences, Florida follows many of the trends evident across the country. Figure 1 shows the reality of solid waste generation in Florida over the past 20 years. The downward trend since 2005 is a combination of and on the recent economic conditions in the U.S. If these trends are compared to national trends and coupled with the population, results indicate that in Florida, the waste generation can be represented as approximately national average of 2.0 kg (4.4 pounds) per person per day. Consistent with national trends, prosperity leads to an increase in MSW generation per person. When these trends are coupled with the future estimated population growth in Florida (Figure 2), the impact of population growth on solid waste disposal needs is staggering. Interestingly, the Florida population growth trend of about 250,000 people per year (ppy) is approximately of 2,500,000 ppy (FAIR, 2006). Clearly, the popularity of the 4 th to increase over the next several generations. As can be seen in Figure 1, it would require an extreme paradigm shift in public policy, public response, and waste disposal disposal needs. To further demonstrate the MSW disposal issues facing Florida, consider the locations in Florida where people density across the State. People clearly like to live in Central Florida. Finally, over the past several years, most states have seen an overall reduction in the number of solid waste disposal facilities. This is demonstrated in Figure 4, which reports the number of active MSW disposal facilities across the country. The national trend over the past 20 years clearly shows that the number of facilities Figure 1. Solid Waste Disposal Trends in Florida (FDEP, 2012, written communication). Figure 2. Florida Population Projections (FL EDR, 2011).

PAGE 3

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 63 MSW disposal facilities per state. Currently Florida has is Where do Floridians place waste in the future and how much capacity is needed? Karst Geohazards in Florida Karst and the underlying problems associated with the geologic conditions are well known to most Floridians, University Of South Florida in Tampa. Perhaps the most famous (infamous) is the May 1981 Winter Park Sinkhole Although detailed formal historical records may be infrequent, and published records, primarily to assess the impacts of subsidence and sinkholes on groundwater resources. Figure present locations of reported subsidence. Florida (i.e., Southwest District and Central District) of subsidence. When the Northeast District is added to this list, the locations of nearly 95 percent of the reported episodes are included. Independent records maintained verbally provided to the authors provide nearly identical results. Clearly, the problems of subsidence and sinkholes around the State to develop Florida Aquifer Vulnerability Floridan Aquifer is presented in Figure 6. Figure 3. Florida Population Density (FL EDR, 2011). Figure 4. MSW Landfills in the U.S. (USEPA, 2009). Figure 5. Map Showing Reported Subsidence Areas (FDEP, 2010, written communication). Figure 6. Florida Aquifer Vulnerability Assessment (FAVA) Map for the Floridan Aquifer (FDEP, 2010, written communication).

PAGE 4

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 64 to the groundwater table; (ii) hydraulic head difference distance to known karst features; (v) overburden soil permeability; and (vi) aquifer system overburden. Comparing Figures 5 and 6 provides the compelling observation that the most valuable groundwater resource in the State is most vulnerable in the areas where virtually 95 percent of the reported subsidence is located. and hydrogeologic conditions with the previous section regarding solid waste needs, a foreboding observation develops. It is anticipated that the areas where the in the future. Further, this area is where the potential for subsidence and sinkholes is highest (Figure 5) and where the Floridan Aquifer is most vulnerable (Figure 6). Furthermore, it is noted that the areas of subsidence and aquifer vulnerability, hereinafter referenced as sensitive areas, comprise nearly 60 percent of the total land area in the State. Clearly, a hasty reaction to simply would place a hardship on other areas of the State where residence of Central Florida due to high transportation challenges across the State. Technical differences of opinions are inevitable between environmental groups, consistent, defensible, and fair solid waste policies and guidelines are developed and enforced. Guidance Documents The FDEP has developed and currently maintains and enforces solid waste regulations in the State that exceed the U.S. Environmental Protection Agency (USEPA) Subtitle D requirements regarding the siting, design, construction, operations, and performance of MSW disposal facilities. The FDEP has followed USEPA guidelines and like other states that experience karst geologic conditions (including Alabama, Arkansas, Kentucky, Minnesota, Pennsylvania, and Tennessee), has taken aggressive regulatory positions regarding the protection of groundwater resources by establishing: (i) guidelines. With regards to groundwater monitoring requirements, these State regulations acknowledge that the groundwater regime in karst geologic settings comprised of granular media. The FDEP has taken a strong position that its policies are directed to protecting groundwater and minimizing potential adverse risks to its aquifer systems. Therefore, the FDEP regulations explicitly recognize the importance for the applicant to regime and develop a groundwater monitoring system FDEP Rules and Regulations regime, karst can also impact the structural stability the regulations in most other states) address issues of of the Florida Administrative Code (FAC) are cited to provide examples of how regulations (and regulators) by authors for emphasis): prohibition for siting requirements for all solid waste disposal facilities states unless authorized by a another Department rule or a Department license geological, design, or operational features, no person shall store or dispose of solid waste. in an area where geological formations or other subsurface features will not provide support for the solid waste; location requirements site shall provide structural support for the facility including total wastes to be disposed of and structures to be built on the site; design requirements soil and geosynthetic liners shall be installed upon a base and in a geologic setting capable

PAGE 5

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 65 test for reasonable assurance. The permit application and and scrutiny. In many cases the interpretations of the geotechnical investigation and geologic characterization an independent assessment by the public reviewers regarding regulatory compliance and reasonable assurance. In addition, particularly for permits involving professionals. This often leaves the FDEP in the professionals and the reality that regardless of its decision and potential litigation from either the applicant or the public. The FDEP has successfully faced the realities of this regulatory environment since the promulgation topics where controversy or technical challenges are anticipated, FDEP (and regulators in other states) have expectations regarding the permitting process. applicant and public response regarding recent MSW In addition, FDEP recognizes future challenges facing this region as summarized in the previous section of this paper. To address these issues, the next section describes a proactive approach that FDEP has taken regarding the siting, permitting, design, construction, operation, and monitoring of MSW disposal facilities located in karst geologic settings. Development of a Technical Advisory Group (TAG) To assist the agency in this initiative, the FDEP has comprised of a number of engineers, geologists, and scientists from both the public and private sectors with expertise in karst assessment to help the agency in the development of additional technical guidance. This guidance will assist: (i) the applicant in its preparation of MSW permit applications; (ii) the FDEP personnel responsible for technical review of the permit application of providing structural support to prevent overstressing of the liner due to settlements and applied stresses; and geotechnical site investigation requirements and construction and demolition (C&D) debris disposal facilities states the prior to any that are necessary for the design, construction, the facility and shallexplore and address the ground, lineaments, and sinkholes. applicant to make the requisite demonstrations and example, with regards to geotechnical site investigation requirements above, one engineer may believe that the site can be adequately characterized using 1 boring per hectare (2.4 borings per acre), while another may believe that variability at the site warrants a density of greater than 4 borings per hectare (10 borings per acre). In many cases, the regulations leave decisions to the discretion of the professionals tasked with preparing the permit application. The FDEP, however, recognizes that even and geologic characterization studies require the educated interpretation of data and facts. This interpretation of these study results must be provided in an application prepared on behalf of the applicant that demonstrates compliance with the FDEP regulations. To issue an FDEP permit for an MSW facility, the applicant must provide reasonable importantly states that reasonable assurance means the existence of a substantial likelihood, although not an absolute guarantee, that the proposed activity and applicant will comply with agency rules, laws, orders and permit conditions. It does not mean proof that a facility will not fail. It is noted that this section of the regulations recognizes that the permitting test is for reasonable assurance not for absolute assurance. other states) requires that professional engineers and geologists prepare technical applications that provide the previously stated reasonable assurance. The

PAGE 6

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 66 determining that stabilization was achieved; and (v) monitoring a disposal facility for sinkhole formation. A brief discussion of the approach used to address each of these tasks and preliminary recommendations by the Characterizing Site for Sinkhole Potential characterize the potential site. At a minimum, this task includes: (i) review of geologic information regarding mile) radius of the site; (ii) review of historical aerial spanning several years (or decades when possible) followed by physical inspection of the site with photos in hand; (ii) geophysical investigation along several transects, including orthogonal transects that intersect soundings; and (iv) physical invasive investigation, sampling, and in situ testing. This strategy recognizes that the potential for sinkhole development starts at should be cited and details of the features should be included in the permit application. With regards to the geophysical testing, electrical resistivity and ground that have been used successfu l ly in Florida. Other techniques will be considered. It is critically important sounding locations. Invasive testing can include hollow stem auger or mud rotary drilling, with the latter being preferred due to the ability to note rod drop and slurry loss. Soil samples and rock cores should be collected. In situ testing can include the Standard Penetration Test is currently considering the recommended minimum number of geophysical transects, the depth and extent of as well as the recommended laboratory tests. The from the geological and aerial photograph review. Assessing Sinkhole Potential Risks assessment of the risk of a sinkhole developing at the proposed MSW disposal site. The FDEP would like to verify compliance and reasonable assurance; and (iii) the public in its review and critique of the permit FDEP in the development of technical guidance for the siting, permitting, design, construction, operation, and monitoring of MSW disposal facilities sited in that will help: (i) the FDEP decide how to evaluate these permit applications and then issue the solid waste disposal permits; and (ii) the applicant know what information should be submitted in these permit acknowledged that in developing the guidance, there needs to be a balance between cost of assessment and investigation and the risk of failure. Furthermore, the guidance needs to apply both good science and group of professionals, FDEP required that members set aside personal interests, if any exist, and focus on what is really good for Florida. Specific Objectives of the TAG regulations was protection of groundwater resources. validated the intention of the Subtitle D regulations. (2002) demonstrated that the composite liner system design and the leachate management system design and operations requirements promulgated by the Subtitle D protective of groundwater. As mentioned previously, the challenge in the geologic setting in Central Florida is to assure the structural integrity of the liner system. physical and geophysical techniques for characterizing sinkhole potential of a site; (ii) determining if potential sinkhole risks for a site are low, moderate, or high; (iii) deciding when a site cannot be used or can be used if properly stabilized; (iv) stabilizing a site and

PAGE 7

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 67 and replacement. The stabilization efforts will require that the applicant demonstrate the effectiveness of the selected stabilization remedy. With reference to Figure overburden soil followed by treatment of the foundation bedrock. One aspect of stabilization that concerns the in which the plugging of one hole in the dike simply caused a new hole to form. Stabilization alternatives will need to consider site wide stabilization efforts or at least the impacts of localized stabilization efforts on overall site stability. Monitoring for Sinkhole Formation The FDEP acknowledges that the construction of a the design of surface water management ponds, (i.e., unloading) the foundation soils can increase the the assessment to report a high, medium, or low information regarding the potential size of the sinkhole, location and size of the reported subsidence features so that regional lessons can be reported based on past low risk. Evaluating Site Suitability assessing risk should a sinkhole develop) is to develop MSW disposal facility. Although in its preliminary state, the previous step and the assessment of site suitability. that all sites are potentially suitable for development engineering control. The FDEP does not necessarily want to condemn a site a priori but clearly wants to make the applicant aware that certain geologic conditions will render a site essentially unsuitable due to the likelihood of sinkhole development and the system. Figure 7 provides an example of a potentially unsuitable site. This aerial map, when combined with historical photos from the previous 20 years, showed a gradual and steady development of large sinkholes that extend to the ground surface and grow over time. For most sites (and in particular this site), it is important to mechanism to assess whether it is economical to arrest future sinkhole development or better to simply abandon the site. Defining Site Stabilization Measures that may be required to improve the suitability of the site to a level that provides reasonable assurance to the FDEP that the site can be developed in compliance site conditions, techniques may include (but are not Figure 7. Example of a Potentially Unsuitable Site.

PAGE 8

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 68 Conclusion The FDEP has developed and currently maintains and enforces solid waste regulations in the State that exceed the national standards but desires to improve the MSW currently the 4 th most populated State and Floridians generate solid waste at a rate that exceeds the national Central and Northeast Florida comprise nearly 60 percent of the total land area in the State and is founded subsidence due to sinkholes. These same areas are within zones where the valuable groundwater resources are considered most vulnerable and include areas of the highest population density. The FDEP has developed a the permit applicants provide the FDEP a reasonable assurance that the siting, design, construction, operations, and monitoring of the proposed facility is in compliance with FDEP regulations. The authors solicit feedback from conference participants (and proceedings readers) regarding techniques to improve the strategies References Alabama Department of Environmental Management: Land division Solid waste program, Division Environmental Management [ADEM]; [cited 2012 Nov 24]. 179 p. Available from: Arkansas Pollution Control and Ecology Commission: Regulation 22, Solid waste management rules [Internet]. Arkansas Department of Environmental Quality [ADEQ]; [cited 2012 Nov 24]. 202 p. Available fromt: Bonaparte R, Daniel DE, Koerner RM. 2002. Assessment and recommendations for improving the performance of waste containment systems. [Internet]. Florida Department of Environmental Protection [FDEP]; [cited 2012 Nov 24]. 114 p. Available from: that there will be recommendations for monitoring the site, as well as the surrounding parcels of land, for early indications of new sinkhole formation. Unfortunately, the solid waste itself decomposes over time resulting These recommendations will include provisions by the applicant for modifying operations and addressing these features should they occur. recommendations and minimum expectations regarding exploration and investigation programs that are based applicants. Feedback and Recommendations from Karst Experts The purpose of this paper was to describe a strategy currently being implemented by the FDEP to karst geologic settings. Several of the charges to geologic phenomenon. The authors recognize that the participants at this conference (and readers of authors explicitly solicit feedback and suggestions recommendations regarding: (i) other similar efforts Florida that need to be considered; (iii) geophysical should be considered; (iv) stabilization options that have (or have not) worked effectively; and (v) considered. The authors recognize that the experience the experience of the participants will be useful in

PAGE 9

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 69 Florida: demographics report 2011 [Internet]. Demographic Research [EDR]; [cited 2012 Nov 24]. 25 p. Available from: Kentucky legislature: Kentucky administrative regulations: Title 401: Energy and environment cabinet department for environmental protection; Kentucky Department for Environmental Protection [KDEP]. [cited 2012 Nov 24]. Available from: 2050: four immigration scenarios [Internet]. 2006. [Place of publication unknown]: Federation for American Immigration Reform [FAIR]; [cited 2012 Nov 24]. Available from: waste: [Internet]. Minnesota Pollution Control Agency [MPCA]; [cited 2012 Nov 24]. Available from: Tennessee Department of Environment and Conservation: Rules of Tennessee Department of Environment and Conservation: Solid Solid waste processing and disposal [Internet]. Tennessee Department of Environment and Conservation [TDEC]; [cited 2102 Nov 24]. Available from: solid waste [Internet]. Pennsylvania Department of Environmental Protection [PDEP]; cited 2012 Nov 24]. Available from: USEPA. 2009. Municipal solid waste in the United

PAGE 10

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 70


printinsert_linkshareget_appmore_horiz

Download Options

close
Choose Size
Choose file type
Cite this item close

APA

Cras ut cursus ante, a fringilla nunc. Mauris lorem nunc, cursus sit amet enim ac, vehicula vestibulum mi. Mauris viverra nisl vel enim faucibus porta. Praesent sit amet ornare diam, non finibus nulla.

MLA

Cras efficitur magna et sapien varius, luctus ullamcorper dolor convallis. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Fusce sit amet justo ut erat laoreet congue sed a ante.

CHICAGO

Phasellus ornare in augue eu imperdiet. Donec malesuada sapien ante, at vehicula orci tempor molestie. Proin vitae urna elit. Pellentesque vitae nisi et diam euismod malesuada aliquet non erat.

WIKIPEDIA

Nunc fringilla dolor ut dictum placerat. Proin ac neque rutrum, consectetur ligula id, laoreet ligula. Nulla lorem massa, consectetur vitae consequat in, lobortis at dolor. Nunc sed leo odio.