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Hydrogen Sulfide Emissions Characterization

Excerpts From a Report orginally Submitted in Support of 26th WARD WPCP Preliminary Treatment & Solids Handling Facility Upgrade Construction Contract

By: Timothy Minnich, MS, QEP
Tel: (908) 409-9900
Email Mr. Minnich

Website: www.MSIAir.net

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EXECUTIVE SUMMARY

The New York City Department of Environmental Protection (DEP), Bureau of Engineering Design & Construction (BEDC), through its engineering consultant, Hazen and Sawyer, P.C., is currently upgrading the wastewater and residuals handling system at the 26th Ward WPCP in the Borough of Brooklyn, New York (DEP Contract 26W-20). This report presents the hydrogen sulfide (H2S) emissions inventory necessary to support a comprehensive City Environmental Quality Review (CEQR) air quality analysis for this compound.

This report is a revision of the March 2002 report, “Results of a Hydrogen Sulfide Emissions Characterization for the 26th Ward Wastewater Treatment Plant Upgrading.” Although the upgrade project that report was intended to support was subsequently cancelled, the DEP determined that the emissions work performed for the original upgrade could be used to satisfactorily support the current upgrade project without additional field measurements.

Accordingly, the DEP directed Hazen and Sawyer to modify the March 2002 report (and the corresponding CEQR analysis) to reflect the current upgrade project. Minnich and Scotto, Hazen and Sawyer’s air quality consultant for the original emissions measurements and CEQR analyses at this facility, was retained to prepare this revised H2S emissions characterization. The revised CEQR analysis for H2S will be prepared upon DEP review and acceptance of this report.

Field work for this H2S emissions characterization study was performed between July 9 and September 6, 2001 under the direction of Hazen and Sawyer. Emphasis was placed on collecting emissions data during times of dry-weather flow, i.e., during those conditions within the normal range of plant operating limits likely to enhance anaerobic (septic) conditions necessary for H2S generation. All measurements were made during the summer when influent temperatures were at their annual peak, as anaerobic activity is directly proportional to temperature.

A total of 174 individual H2S emission-rate estimates spanning a range of facility conditions and operating practices for six source groups are derived from the field measurements. From this information, a technically defensible facility-wide emissions inventory is developed. Sufficient measurement and facility operating data were collected to ensure that “credit” could be taken for each upgrade component shown to materially reduce H2S emissions. Strict control of all sampling methods and instruments was employed in accordance with the most recent USEPA guidelines and requirements for the collection of evidentiary field-measurement data. Calibrated Jerome meters were employed for all H2S measurements.

Two emissions-estimation methods were employed: the mass-balance technique and the area- source technique. The mass-balance technique was employed for the buildings (pump station screening rooms, sludge thickeners, and sludge storage tanks); it involves multiplying the volume of ventilated air by a representative H2S concentration derived from an appropriate treatment of indoor data.

The area-source technique was employed for the process tanks; it involves an assessment of source attribution and the use of an appropriate dispersion model, together with onsite meteorological data, to estimate a unique, conservative emission rate for each 15-minute monitoring event. The principal component of this revised emissions characterization involves replacement of the ISCST3 dispersion model used in the original analysis with USEPA’s new guideline model, AERMOD – a much more sophisticated model with improved accuracy in near- source, downwind locations for area-type sources.

Because the ISCST3 Model (and even AERMOD, for that matter) does not perform well in the very stable sea breeze environment, and because much of the H2S measurement work at the preliminary settling tanks was expected to be performed when the wind was from the south (i.e., blowing from Jamaica Bay), a controlled tracer-gas measurement program was employed to augment the H2S measurements for this source. Carried out concurrent with the emissions field work, this program improved model accuracy by allowing the vertical dispersion algorithm contained in each model to be bypassed and replaced with measured, site-specific vertical dispersion curves unique to each emission-rate measurement.

Based on this analysis, a revised H2S emissions inventory is derived for each source group to support the CEQR air quality analysis. This inventory, presented below, will provide the basis for development of a compliant operating scenario to ensure that maximum offsite facility impacts do not exceed applicable H2S standards.

Source

Emission Rate (g/s)

preliminary settling tanks

0.0679

aeration tanks

0.0003

final settling tanks

0.0002

high-level pump station

0.0002

low-level pump station

0.0002

sludge thickeners

0.0002

sludge storage tank 1

0.0007

sludge storage tank 2

0.0003

sludge storage tank 3

0.0003

SECTION 1 - INTRODUCTION AND OBJECTIVE

The New York City Department of Environmental Protection (DEP), Bureau of Engineering Design & Construction (BEDC), through its engineering consultant, Hazen and Sawyer, P.C., is currently upgrading the wastewater and residuals handling system at the 26th Ward Water Pollution Control Plant (WPCP) in the Borough of Brooklyn, New York (DEP Contract 26W-20). This report presents the hydrogen sulfide (H2S) emissions inventory necessary to support a comprehensive City Environmental Quality Review (CEQR) air quality analysis for this compound.

This report is a revision of the March 2002 report, “Results of a Hydrogen Sulfide Emissions Characterization for the 26th Ward Wastewater Treatment Plant Upgrading” (hereinafter referred to as the March 2002 report). Although the upgrade project that report was intended to support was subsequently cancelled, the DEP determined that the emissions work performed for the original upgrade could be used to satisfactorily support the current upgrade project without additional field measurements. Accordingly, the DEP directed Hazen and Sawyer to modify the March 2002 report (and the corresponding CEQR analysis) to reflect the current upgrade project. Minnich and Scotto, Inc., Hazen and Sawyer’s air quality consultant for the original emissions measurements and CEQR analyses at this facility, was retained to prepare this revised H2S emissions characterization. The revised CEQR analysis for H2S will be prepared upon DEP review and acceptance of this report in accordance with the protocol dated January 2008.

A total of 174 individual H2S emission-rate estimates spanning a range of facility conditions and operating practices for six source groups are derived from the field measurements. From this information, technically defensible emissions inventories are developed for each source group (build scenario). Sufficient measurement and facility operating data were collected to ensure that “credit” could be taken for each upgrade component shown to materially reduce H2S emissions.

The area-source technique was employed for the process tanks. Further explained in Section 4, the area-source technique is a type of mass-balance procedure which involves an assessment of source attribution and the use of an appropriate dispersion model, together with onsite meteorological data, to estimate a unique emission rate for each 15-minute monitoring event.

The principal component of this revised emissions characterization involves replacement of the ISCST3 dispersion model used in the original analysis with USEPA’s new guideline model, AERMOD – a much more sophisticated model with improved accuracy in near-source, downwind locations for area-type sources.

Field work was carried out between July 9 and September 6, 2001. Because the ISCST3 Model does not perform well in the very stable sea breeze environment, and because much of the H2S measurement work at the preliminary settling tanks was expected to be performed when the wind was from the south (i.e., blowing from Jamaica Bay), a controlled tracer-gas measurement program was employed to augment the H2S measurements for this source. Carried out concurrent with the emissions field work, this program improved model accuracy by allowing the vertical dispersion algorithm contained in each model to be bypassed and replaced with measured, site-specific vertical dispersion curves unique to each emission-rate measurement.

To support DEP review of the March 2002 report, the emissions method underwent critical review by D. Bruce Turner, generally considered to be the world’s top authority in the application of Gaussian dispersion theory – the underlying basis of the method. Judged still applicable for this revised analysis, his report is reproduced herein as Appendix 1.

Large portions of the March 2002 report remain intact and are directly applicable to the new CEQR analysis. However, in addition to the incorporation of AERMOD, there are several other changes and issues of note:

!       Section 2 of the March 2002 report (Background) has been replaced with a new Section 2 in order to reflect the current upgrade project.

!       The Hendrix Street Canal, a sporadic yet significant H2S source during the field measurement program, will soon be dredged and thereafter not pose a concern for adverse offsite impacts. Accordingly, this source is eliminated from the monitoring results (Section 6) and associated emissions characterization (Section 7). All quality control data (Section 9), raw analysis data (Attachments A and B), and calculation worksheets (Attachment C) remain unaltered, however, as measurement data from this source is integral to the overall treatment of quality assurance.

!         As discussed in the March 2002 report, an ancillary H2S measurement program was performed for the preliminary settling tanks in an attempt to quantify the conservatism in the predicted concentrations. This limited effort involved collection of a second set of downwind path-averaged H2S data, concurrent with selected monitoring events, along a parallel measurement path 10 meters downwind of the original path. Because the objective was not achieved, however, and since the measurement data is used for quality control purposes, this data is treated in a manner similar to that for the Hendrix Street Canal.

!       New (electronic) versions of all figures in Sections 6 and 7 have been integrated into this report to facilitate document reproduction.

!       Attachment E of the March 2002 report (Treatment of Atmospheric Stability to Support Emissions Assessment: Area Sources) is replaced with a new Attachment E (Supplemental Meteorological and Atmospheric Dispersion Analyses: Area Sources) to reflect the fact that AERMOD simulates atmospheric dispersion directly from atmospheric turbulence (without consideration of atmospheric stability).

!   Attachments A, B, D, F, and H (which provide original raw field data, AERMOD input and output files for area-source emission-rate estimates, and calibration certificates) are included herein only as electronic files due to their large size.

All work was performed in accordance with the H2S Emissions Estimation Procedure (February 2001) which, together with the requisite Sampling and Analysis Plan and Quality Assurance Project Plan, provided detailed data-collection methodologies for the generation of the facility- wide H2S emissions inventory. As stated in these planning documents, the objective of this investigation was the generation of technically defensible estimates of gaseous H2S emissions emanating from potentially significant process-unit sources at the 26th Ward WPCP.

Section 2 of this report presents the background and project overview. Section 3 identifies the emissions sources investigated. Section 4 presents the emissions-estimation methods employed for each source. Section 5 describes the measurement equipment employed. Section 6 presents the monitoring results. Section 7 presents the emissions characterization (revised work) generated from the monitoring data collected. Section 8 presents development of the emissions inventory (revised work) for subsequent use in the CEQR compliance assessment. Finally, Section 9 details the quality assurance program and the quality control measures employed before, during, and after data collection (unaltered).

SECTION 2 - BACKGROUND AND PROJECT OVERVIEW

The 26th Ward WPCP is located on a 57.3 acre site at the intersection of Flatlands and Van Siclen Avenues in southeastern Brooklyn, New York (Block 4440, Lot 1, and Block 4452, Lot 150). The plant parcel abuts Flatlands Avenue to the north, Van Siclen Avenue to the west, and the Belt Parkway to the south; the Hendrix Street Canal separates the site from the land to the east. The plant, constructed in the 1940s, was upgraded or expanded in the 1950s, 1960s, and 1970s. Sludge dewatering and cake storage facilities were added in the 1990s.

The 26th Ward WPCP is an activated sludge plant that treats combined sewage. The treatment process for the sewage consists of screening, pumping, primary settling, aeration, final settling, and disinfection. The treatment process for the sludge consists of degritting, thickening, digesting, storage, and dewatering (prior to offsite disposal). The plant treats up to 150 percent of the design dry-weather flow (DDWF) of 85 million gallons per day (mgd) (or 127.5 mgd) through secondary treatment. An additional 42.5 mgd (or 170 mgd total, which represents 200 percent of the DDWF) is treated in the preliminary (primary) settling tanks and undergoes disinfection via chlorination.

The wastewater flows to the plant through two interceptor sewers. One interceptor, from Fresh Creek, is referred to as the low-level interceptor and receives about two-thirds of the total plant flow. The other interceptor, from Hendrix Street, is referred to as the high-level interceptor and receives the remaining flow (one-third). Plant effluent is discharged to the Hendrix Street Canal.

Primary combustion sources include two boiler systems (one in the Main Building and the second in the Sludge Dewatering Facility), a digester gas flaring system, and an emergency generator system.

Per requirements of combined sewage overflow (CSO) Order on Consent #CO2-20000107-8, the City of New York and DEP have agreed to treat an additional 50 mgd of wet-weather flow through the primary treatment and disinfection process at this plant. The increase in treatment capacity will be accomplished via plant additions and modifications under several principal construction contract packages, including this Contract 26W-20 Preliminary Treatment & Solids Handling Facilities. Under future Contract 26W-21 Digesters, Thickeners & Administration, upgrade of sludge processing treatment systems and construction of a new Administration Building are planned. Under future Contract 26W-22, a new Raw Sewage Pump Station & Main Substation is planned. Under Contract 26W-23, a wet-weather outfall and potential CSO chlorine contact tank are planned to complement the plant’s existing outfall and two chlorine contact tanks, and to meet the increased plant capacity of 220 mgd.

Download PDF to continue reading report, footnotes, figures, tables, and references.


Timothy R. Minnich, President, MS, QEP, is a Meteorologist and Atmospheric Scientist with over 40 years experience in the design and management of a wide range of ambient air and meteorological investigations under CERCLA and the Clean Air Act. He is a recognized technical expert on high-profile legal cases, with assignments involving forensic meteorology and reconstruction of inhalation scenarios in relation to community exposure to hazardous air pollutants (HAP). He is a nationally recognized expert in the application of optical remote sensing (ORS) for hazardous waste site remediation. He has designed and managed more than 25 ORS field investigations and air dispersion model validation studies since the promulgation of U.S.EPA (EPA) Method TO-16 for open-path FTIR (Fourier-transform infrared) spectroscopy in 1988.

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