11th North American Waste to Energy Conference

Copyright C 2003 by ASME

NAWTEC11-1677 LONG-TERM OPERATING RESULTS - ASH MONOFILL

ABSTRACT

DR. RICHARD W. GOODWIN, P.E. ENVIRONMENTAL ENGINEERING CONSULTANT

P.O. BOX 220628

WEST PALM BEACH, FLORIDA 33422 USA

561-689-3525; FAX: 561-683-9507 richard.w.goodwin@worldnet.att.net

An ash monofill was studied from 1997 to 2001. Monitoring results of the lined landfill showed viability of liner since groundwater standards were not exceeded. Raw leachate of RCRA heavy metal leachate results show Chromium reaching groundwater standards while Lead, Cadmium and Zinc slightly exceed these standards. An upset incident of pre­mature set - up of lime-laden ash caused a back - up and overflow condition in 1994. Adding water of solubilization and field compaction achieves optimal geo-technical properties and reduces heavy metal leachate. This water addition would have also reduced fugitive dust concerns. These principles of sound engineering management of MWC residues were well-known and widely publicized. If the landfill operator had applied these principles the upset incident could have been avoided. Long-term trends of RCRA heavy metal leachate results show compliance with groundwater standards, although Lead, Cadmium and Zinc exceed these standards. Application of sound engineering placement practice would have reduced these long-term trends. USA Regulatory officials should consider incorporating these principles into residue management recommendations, following Environment Canada's example. Recognition and implementation of these principles would confirm that incinerator ash can be properly managed - to alleviate concerns - justifying their beneficial reuse.

INTRODUCTION

The non-empirically based environmental rhetoric claiming Municipal Waste Combustion [MWC] is hazardous and poses a threat to groundwater parallels the 16 years odyssey of the residue loaded on board the cargo ship Khian Sea (1). From 1986 to 2001, this material generated at Philadelphia returned to Pennsylvania - resulting in needless costs and wasted efforts. The controversy surrounding MWC residue abated with a Supreme Court decision, requiring its testing as a hazardous waste; i.e., so-called Resource Conservation and Recovery Act [RCRA] testing protocol. The author has

113

stated publicly that such testing labels the residue as hazardous - without regard to scientific evidence (2). The Supreme Court ruling overlooked empirical field results demonstrating its environmentally benign behavior (3).

Operating results of a residue monofill (1997 to 2001) are presented that provide insight into optimal management of MWC Residues. Analogous to the barge's unnecessary expenditures and regulatory concerns, MWC residue regulatory classification should be reviewed by elected and appointed officials - resulting in a non-hazardous reclassification and, in turn, promoting its beneficial use.

SITE DESCRIPTION

A 35 acre ash monofill has been operating since 1989. This facility receives about 16, 000 tons per month Municipal Waste Combustion [MWC] Residue. The monofill is located close to a public playground and surface water. Public concern has focused on facility's impact to ground/surface water and dust emissions. Figure One depicts the salient features of the landfill. Background and down-gradient monitoring wells measure the viability of the monofill's liner system. Raw leachate is collected from man-holes and pumped to a near-by sewage treatment plant. A municipal agency operates this landfill and performs all sample collection and laboratory analysis. Quarterly results are submitted to state regulators.

Groundwater Monitoring Results

Table One shows the down-gradient range of RCRA heavy metals for the period 1997 - 2001. With the exception of an incident related to Selenium and Chromium, during 1998, down-gradient results conform to groundwater standards. Such results demonstrate liner viability and groundwater protection.

Table Two, representing background groundwater monitoring, suggests the Selenium incident may be attributable to natural causes, i. e. not derived from landfill leachate. A comparison of these tables shows levels of Cadmium and Chromium possibly related to landfill leachate. A following section will discuss leachate issues.

114

RESIDUE MANAGEMENT - PLACEMENT

Operational problems have occurred due to failure to appreciate in-situ pozzolanic reaction of lime-laden ash -causing leachate back-up and overflow. In 1994, lime was added to the ash to immobilize Lead and Cadmium. This lime/ash material reduced leachate collector pipe opening -causing a back-up and overflow, as depicted by Figure Two.

The inherent pozzolanic-like behavior of lime-laden MWC residue had been identified in 1988 providing warning time for the prudent operator to avoid pre-mature set­up(4). The application of sound engineering practice to ash placement was recognized and publicized before 1994 (5,6). Avoiding the condition of premature pozzolanic reaction has been recognized occurring with coal combustion by-products (7) and analogized to MWC residues later on (8).

Sound engineering practice of ash placement recognizes the relationship between achieving desired Geo-Technical Property and Optimal Moisture Content while maintaining adequate 'Water of Solubilization' (or % Final Solids) to ensure reacting Pozzolanic Constituents with Free Available Lime (9). Adhering to these principles requires Proper Placement Control Management - Field Compaction and Water Addition. Improved field placement (i.e., compaction, addition of dust suppression water) of ash could increase density and reduce permeability to decrease leachate rate through the buried ash (9). These practices have been embraced by Environment Canada (10).

These principles of sound engineering management of MWC residues were well-known and widely publicized. If the landfill operator had applied these principles the upset incident could have been avoided.

Landfill RCRA Heavy Metal Leachate

As previously stated, Cadmium and Chromium exceeded groundwater standards during one sampling period in 1998. This occurrence might have been avoided by applying the principles of proper engineering residue placement.

Table Three shows the RCRA heavy metal leachate from 1997 to 2001. These results exceed both groundwater standards and comparison to the seven other ash monofills. Such

lIS

occurrences are not irrevocable. The application of sound engineering practice could have avoided the pattern of leachate behavior (12).

Long Term Trends RCRA Heavy Metals Leachate

As shown by Figure 3, Chromium leachate's logarithmic trend-line approaches groundwater standard over the sampling period. Applying a logarithmic trend-line is justified based on a mathematical predictive relationship derived from another operating ash monofill (12).

Constant = [HM] -liT

Where T = curing time, HM = RCRA heavy metal field leachate (mg/l) present at time, T; and Constant = slope of semi-log plot and varies per heavy metal species [mg/l]

Table 4 shows the long-term trends of all RCRA heavy metals and their comparison to Groundwater Standards. Long-term trends of Cadmium, Lead and Zinc exceed these standards. Since this monofill is not optimally managed, application of sound engineering placement practice would have reduced these long-term trends.

Landfill Inorganic Leachate

Based on 1998 laboratory results the following tabulation shows excesses of inorganic constituents.

EXCESS RANGE VS. REGULATORY CRITERIA

CONTAMINANT EXCESS RANGE (ug/l) CRITERIA (ug/l)

IRON 330 - 140000 300

MANGANESE 430 - 11450 300

PHENOL 0. 006 - 6. 97 mg/l 0.005 mg/l

COLOR 18 - 30 15

CHLORIDES 1150 - 15200 250

SODIUM 24000 - 670000 20000

SULFATE 1140 - 1500 mg/l 250 mg/l

TDS 520 - 27900 mg/l 500 mg/l

POTASSIUM 0.012 - 0.054 0.001

1 16

These exceedances prompted the host community to request that the operator perform more frequent sampling and testing, to determine if the exceedances are just sporadic or if they represent a more consistent trend. The latter condition would suggest a greater potential threat to local groundwater quality. Elected community officials requested the state regulatory agency to explain the health and/or environmental consequences of the specific contaminants tested. The operating procedures of the monofill were questioned - creating an adversarial condition.

Fugitive Dusting

Proximity to the playground caused additional cause for concern by the citizens. Anecdotal incidents of fugitive dusting and local complaints further exacerbated the relationship between operating agency and the local community. Dust suppression water could have been added as a normal component of sound engineering residue placement practice (13).

SUMMARY

Notwithstanding the application of optimal residue placement, the ash monofill groundwater monitoring results show compliance with groundwater standards. Long-term trends of most of the RCRA heavy metal leachate results show compliance with groundwater standards, although Lead, Cadmium and Zinc slightly exceed these standards. Proper site management would have avoided these excess conditions - as comparison to other ash monofills have demonstrated. Regulators and Operators of MWC residues are urged to apply the principles of sound engineering practice to avoid creating local citizen concerns.

References:

(I)Reeves, H.; "A Trail of Refuse"; The New York Times; [Sun. 2/18/01]

(2) Schneider, K.; "Incinerator Operators Say Ruling Will Be Costly"; NY T IMES 5/3/94 (3) Hodges, D. ; "Supreme Court's Incinerator Ash Ruling a Hollow Victory for EDF"; Florida Specifier; June 1994

1 17

(4) Goodwin, R. W. ; "Non-Hazardous Concrete-Like Behavior of Ash From Resource Recovery Systems Equipped with Acid Gas Treatment "; pre-sented at the U. S. Conference of Mayors 7th Annual Resource Recovery Conference (Washington, D. C. ; Mayflower Hotel; Mar. 24- 25, 1988). (5) Goodwin, R. W. and Forrester, K. E. ; "Engineering Management of MSW Ashes: Field Empirical Observations of Concrete-like Characteristics"; Proceedings USEPA International Confererence of Municipal Waste_Combustion; Diplomat Hotel; Hollywood, FL. ; 4/11-14/89. (6) Goodwin, R. W. and Forrester, K. E. ; "MSW-Ash Field Study: Achieving Optimal Disposal Characteristics II; Journal of the Environmental Engineering Division; American Society of Civil Engineers [ASCE] , Vol. 116, No. 5, Proc. Paper 25094, Sept/Oct 1990, pp. 880-889. (7) Goodwin, R. W. ; "Design Optimization of a Flue Gas Desulfurization Sludge Handling System"; Proceedings of Columbia University Seminar on Pollution and Water Resources Vol. IX 1975-1978; N. J. Dept. of Environmental Protection, Bureau of Geology & Topography; Bulletin 75-C; pp 11-118. (8) Goodwin, R. W. ; "Non-Hazardous Concrete-Like Behavior of Ash From Resource Recovery Systems Equipped with Acid Gas Treatment "; pre-sented at the U. S. Conference of Mayors 7th Annual Resource Recovery Conference (Washington, D. C. ; Mayflower Hotel; Mar. 24-25, 1988). (9) Goodwin, R. W. ; IIEngineering Management: Ash Monofill Demonstrating Liner-Like Properties II ; presented at the Institute for International Research 113rd Annual MSW Incineration Ash Conferencell; held at Sheraton Newark Hotel; Elizabeth, NJ; Sept. 11-12, 1989. (10) Environment Canada; II Interim Recommended Practices for the Management of Solid Residue from Circulating Fluidized Bed Combustion"; Environment Protection Series Report, Quebec Canada1j 1992EPS 1/PG/4; (11) Goodwin, R. W. ; IIDefending the Character of Ash"; Solid Waste & Power; Vol. 6, No. 5, Sept/Oct 1992; pages 18 - 27 (12) Goodwin, R. W. ; Combustion Ash/Residue Management - An Engineering Perspective; Noyes Publications/William Andrew Publishing; Mill Road, Park Ridge NJ 1993 (ISBN: 0-8155-1328-3) (Library of Congress Catalog Card No. : 92-47240); pgs. 50 - 52. (13) Goodwin, R. W. ; II Air Pollution Control Residue Field Leachate Studies Questions Regulatory Lab Evaluation Approachesll; Proceedings of 5th International for Power Generating Industry [Power-Gen 192] ; Orlando Convention Center; Orlando, FL; Nov. 17-19, 1992.

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