Final Draft Technical Report-To Correct

8/13/2019 Final Draft Technical Report-To Correct

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INTRODUCTION

Background

LFG was produced at landfill sites containing decomposable organic wastes. The major

constituents of LFG were methane and carbon dioxide, which were by-products of the biological

decomposition of organic material. Trace concentrations of a variety of other compounds may

also be present in LFG, including hydrogen sulphide, mercaptans, and volatile organic

compounds, which could create nuisance odors, degrade air quality, and result in adverse health

effects. Generally, the amount and character of the organic waste in a landfill directly affects the

quality and quantity of LFG that will be generated; other environmental factors further play a

part in dictating LFG generation.

The methane component of LFG was a potential energy resource, but was also a potential

explosion hazard, and was accepted as a GHG contributing to global warming; the carbon

dioxide component of LFG was generally regarded as being biogenic in origin and was thus not

considered an additional GHG emission. To emphasize the importance of methane emissions

from landfills, methane was considered to be approximately 25 times more heat absorptive than

carbon dioxide on a mass basis with a time horizon of 100 years (IPCC, 2007).

LFG was one of the major anthropogenic sources of methane emissions to the atmosphere in

Canada, accounting for about 20 percent of the nation's total methane emissions in 2007.

Methane emissions produced by the decomposition of biomass in MSW were responsible for 82

percent of the emissions from the waste sector, which also included wastewater handling and

waste incineration. Emissions from MSW landfills increased by 16 percent from 1990 to 2007,

despite an increase in LFG capture and combustion of 71 percent over the same period. The

quantity of methane captured at MSW landfills for flaring or combustion for energy recovery


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purposes in 2007 amounted to 28 percent of the total generated emissions from this source, as

compared to 21 percent in 1990 (Environment Canada, 2009).

In British Columbia for example, Green House Gas (GHG) emissions from waste accounted for

approximately 5 percent of the provinces GHG emissions in 2006. GHG emissions from

landfills accounted for approximately 95 percent of the emissions from British Columbias waste

sector, which also includes wastewater handling and waste incineration (LiveSmart BC, 2008).

Approximately 330 kilotons (kt) of CH4 (or 6,930 kt carbon dioxide equivalent [CO2e]) were

captured by the 65 LFG collection systems operating in Canada in 2007. Of the total amount of

methane collected in 2007, 50 percent (165 kt) was utilized for various energy purposes and the

remainder of the methane gas was flared.

The primary direct benefits of managing LFG were the control of potential adverse impacts and

the reduction of liability for the site owner (i.e. the state). Numerous LFG control projects

indicate that nuisance odors, explosion concerns, and toxic hazards could be effectively

mitigated by implementing LFG management systems.

Furthermore, LFG has numerous additional beneficial uses that stem primarily from the energy

content of its methane component. Many of the technologies for utilization of LFG were well

established and have proven to be economically feasible given suitable site conditions and access

to markets. Electricity generation from LFG was the most prevalent utilization option, but

refining of LFG to pipeline-quality natural gas is becoming more common, as is the formulation

of fuel for vehicles. However, as earlier noted, beneficial use of LFG is highly dependent on

the quality and efficiency of the LFG collection system from an economics standpoint, and thus

it is important to ensure that gas collection systems were correctly designed and installed to

provide a consistent and steady supply of LFG to the utilization facility. Operations were also a


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key component of this equation, as operation of even a well-designed and constructed LFG

management system can at times result in poor gas supply if operations were not performed in a

manner consistent with the objective of fuelling the plant.

Objectives

This project was intended to propose a renewable energy source (biomass) for electricity

generation due to the re-designing of the Beetham landfill. It entailed details of both the merits

and limitations of re-engineering the landfill for electricity generation (some of which were

noted above). These merits includes, the restriction of subsurface migration of Landfill Gas

(LFG) within designated areas of the landfill site, controlled air emissions and odor emitted from

waste by the collection of LFG. The budgetary range for this project was approximately

$1,000,000 - $1,200,000 USD, this cost included the equipment and other auxiliary overheads

necessary to carry out operations.

Scope

The project was implemented into the following stages:

1. Investigation2. Assessment of site3. Consultation4. Procurement5. Implementation6. Evaluation


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Limitations

Some major problems that arose was the availability of trained local technicians and

engineers as well as a number of trained professionals who embarked on this project to redesign

and maintain the landfill.


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Figure 1 Showing methane emission by source


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Figure 1.1 Showing British Columbias waste greenhouse gas emissions (2006)


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INVESTIGATION

A seminar was held on by our company, Eco-Drive Engineering Limited, in order to

educate company heads about the proposed redesigning of the Beetham landfill. As a follow up

to the seminar a series of questionnaires was distributed to the various stakeholders within the

estate. This includes the residents of Beetham Gardens, senior management of SWMCOL,

Ministry Of Housing And Environment, Ministry of Local Government, Ministry of Works and

Infrastructure, Ministry of Energy and Energy Affairs, Environment Management Authority and

The Trinidad and Tobago Solid Waste Management Company Ltd (SWMCOL) and the

President of Downtown Merchants Association. The feedback from the respective stakeholders

was affirmative due to the elucidation of the socio-economic and environmental advantages of

the re-engineered landfill. The results of the survey were charted for further referencing (see

figure 2 below).

Figure 2 Showing results from survey

80%

15%

5%

Survey Statistics

Agree Disagree No Concern


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Assessment of site

Environmental audits: this entailed a systematic, documented, periodic, and objective review by

a regulated entity of facility operations and practices related to meeting environmental

requirements. Types of environmental audit conducted were: management audit, compliance

audit, waste contractor audit, risk definition audit and waste minimization audits. The above

audits were implemented in the following stages: Audit programme planning, pre-audit

preparation (including pre-visit data collection), onsite activities and evaluation of audit data and

reported findings.

Management audit: This determined whether an adequate compliance management system was

established, implemented, and used correctly to integrate environmental compliance into

everyday operating procedures.

Compliance audits: This procedure ensured that all environmental laws as stated by the

regulating body (Environmental Management Authority) was adhered to. This procedure also

determined what specific regulatory requirements were imposed on day to day operations and

ensuring that all operations were in compliance; as well as pointing out possible violations in

time to take proactive measures. Thus, the compliance audit gave a snapshot of plant

operations and procedures, identifying instances of either compliance or violations of them.

Waste contractor audit: This comprised of both a compliance audit and a liability definition audit

to analyze commercial facilities used to store, treat, and dispose hazardous waste.


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Risk definition audit: Analyzed the operations of facilities that handles hazardous materials and

substances. These audit served to assist in obtaining insurance coverage and were required by

some governmental agencies as part of a catastrophe prevention planning.

Waste minimization audits: this examined waste generated by the facility with the objective of

identifying viable actions to reuse, recycle or otherwise reduce the quantity and toxicity of waste

generated. The above mentioned were the types of audit conducted for the re-designing of the

landfill. This was necessary to determine the feasibility of the Beetham landfill project.

Potential Environmental Impacts

Pressure was generally accumulated within a landfill as a direct effect of LFG generation.

Pressure-induced advection/convection of gas, in addition to diffusion of gas through permeable

materials, leads to LFG movement from the waste through either the landfill cover or adjacent

soil, with eventual release to the atmosphere. Impacts of LFG were largely dependent upon the

pathway by which the gas was exposed to humans or introduced into the environment (see

Figure 2.1).

The generation and presence of LFG could possibly (if not managed properly) result in a variety

of adverse impacts, including:

Nuisance odors Emission of GHGs Health issues and toxic effects related to subsurface migration. Explosions and vegetation stressEach of these impacts has prompted the implementation of LFG management systems.


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Figure 2.1 Showing potential environmental impacts of the re-designed landfill


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Nuisance odors

Release of LFG into the air may contribute to odors in the vicinity of the landfill. The

general compounds of concern in LFG as it relates to odor include (SEPA, 2004):

Hydrogen sulphide

Mercaptans

Carboxylic acids

Aldehydes

Carbon disulphide

LFG odors are caused primarily by the hydrogen sulfide and mercaptans that are present in

trace quantities in the gas. These compounds may be detected by sense of smell at very low

concentrations (0.005 and 0.001 parts per million, respectively), and yet may remain far

below health thresholds; the detection of these compounds around landfill sites may thus

primarily be a nuisance issue, although the health and safety limits related to constituents of

LFG must always be understood.

Emission of GHGs

Worldwide methane generated from the landfilling of municipal solid waste represented over

12 percent of total global methane emissions in 2000. Global methane emissions from

landfills are expected to grow by 9 percent between 2005 and 2020. Most developed

countries have regulations that will constrain and potentially reduce future growth in methane

emissions from landfills. However, areas of the world such as Eastern Europe and China are

projected to experience steady growth in landfill methane collection because of improved

waste management practices diverting more MSW into managed landfills (US EPA, 2006).


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Health issues and toxic effects related to subsurface migration

Most of the health and toxic effects related to LFG are centralized around the landfill site and are

primarily of relevance to workers on the site. In the right conditions, LFG may be combustible,

suffocating, and toxic, as is hydrogen sulphide. On-site works in areas such as manholes related

to leachate or condensate management provide a potential area for accumulation of toxic gases.

Additionally, accumulation of LFG in enclosed or low-lying areas on or near landfills may cause

displacement of air, thereby creating an oxygen-deficient atmosphere. This oxygen deficiency

may be severe enough to pose a suffocation hazard to persons in the area. While some of the

trace compounds in LFG are toxic at sufficient exposure concentrations, other compounds are

considered carcinogenic over long-term exposure. However, most of the short and long-term

health effects due to LFG are restricted to the landfill site and can be addressed utilizing properly

developed health and safety procedures and systems.

Explosions

Risk of explosion occurs when the concentration of methane in the air exceeds its lower

explosive limit (LEL). The LEL of methane is approximately 5 percent by volume in air, hence

only a small proportion of LFG, which contains 50 percent by volume methane, is required to

create an explosive condition. The risk of explosion is also associated with confined spaces that

have limited ventilation. In the past, LFG explosions have occurred in structures on or near

landfill sites. These occurrences are generally attributed to LFG migrating through the soil and

accumulating within nearby structures. Note that the potential exists for an explosion when

methane is present in areas with a concentration above the higher explosive limit of 15 percent

by volume in air. LFG explosions occur at an interface where the concentration of methane in

the air is between 5 and 15 percent.


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An explosion can occur when explosive concentrations of LFG exist in the presence of a source

of ignition. This can occur in a confined space and is always a concern when working on LFG

pipes or any areas where LFG can be released from the LFG management system. It is very

important to note that LFG can be lighter or heavier than air depending upon the proportions of

the gases that may be present. It is also important to note that an older site may still pose a

significant LFG migration hazard. The quantity of gas produced begins to decline shortly after

cessation of waste disposal; however, the general gas composition remains essentially the same

except for a reduction in volatile organic compounds (VOCs). As migration is strongly

influenced by the physical setting of the site, hazards may still be present well into the declining

phases of gas generation Explosion hazards resulting from LFG migrating through subsurfacesoils are one of the most important health-related effects attributed to LFG, and thus control

systems was designed with this concern in mind.

Vegetation Stress

Vegetation stress is a sign of LFG migration through the subsurface or through the final landfill

cover and occurs because plant roots are deprived of oxygen; it is also possible that LFG carries

components that are directly toxic to plants (SEPA, 2004). Deterioration of vegetation on and

near landfills may be both an aesthetic and a practical problem. In areas where vegetative cover

is diminished, erosion of the cover may occur. This may lead to a "cascade" effect resulting in

increased LFG emissions.

Vegetation stress alone is generally not a sufficient cause to implement LFG controls. It is,

however, an indication of significant LFG migration in the subsurface, which may lead to other

more serious issues. Vegetation stress on the final landfill cover is also an indication of an area

that may require additional cover material in order to increase the efficiency of a LFG


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management system. Potential LFG impact to vegetation is also a concern when selecting cover

vegetation and final landscaping of the closed landfill. Vegetative stress may also indicate the

need for additional LFG control by the installation of vertical extraction wells in the area.


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CONSULTATION

Acquired technical advice from the Environment and Management Authority, Ministry of

local government, in-conjunction with the Ministry of Environment from British Columbia

Canada on the following:

Site conditions and design considerations Landfill gas management facilities design Condensate management Landfill gas extraction plant Metering Equipment LFG combustion/utilization systems Flaring LFG utilization equipment System installation, operations, and maintenance System optimization

Also consultation was held with the Mayor of Port Of Spain, and city council executives, who

had been influential in initiating and promoting LFG energy project in the Beetham Estate and

ensured that project receive sufficient funding.


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PROCUREMENT

Tendering Process

The tendering process was one of the challenging aspects of this project; it was very lengthy

process, lasting for a total of thirty (30) days. Tenders were sent out to various companies, both

locally and internationally. During this process, companies which didnt meet the specific criteria

were eliminated and the remaining underwent an evaluation. The evaluation consisted of product

quality, on time delivery, development costs, etc. These criteria were assessed by the team along

with an external consultant; the companies with the highest attainable ranks were selected.

Materials and Equipment

With the responses obtained, contractors for the various jobs were selected. The company chosen

for the construction and implementation of the methane gas plant was (TEAM ENGINEERING

SOLUTIONS). Since this company doesnt specialize in all the required aspects needed to

complete the plant another company had to be chosen for the construction of piping and storage

tanks for the gas, and also the installation of the electrical system. The companies chosen for

these aspects of the construction was (Harrys piping engineering limited), and (Spark plus

industries) with the companies all selected, final negotiations and contracts were made; this took

thirty (30) days.


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IMPLEMENTATION

This stage of the project involved designing, construction, and operation of the landfill

gas collection and control system (GCCS). The purpose of a GCCS was to extract LFG

from the waste mass and convey it to a combustion device for flaring or energy use. A

typical GCCS includes the following primary components: extraction wells; a system of

lateral and header (manifold) piping to convey the collected LFG; a condensate

management system; a blower and flare system; monitoring devices; and system controls.

Designing

The overall design was based on expected LFG collection, the type and depth of the

waste, site conditions and operating status (opened or closed), and the overall goals of the

LFG project. Components of the overall design of the landfill project are illustrated in the

figures below:

Figure 2.2a Showing overall design of operations


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Figure 2.2b Showing components of overall construction design of landfill

During the construction phase, the use of proper techniques and quality assurance

procedures was needed to ensure proper system operation and reliability.

Extraction Wells

Gas collection begins in the extraction well, where LFG was extracted from the waste

mass and enters the GCCS. Extraction wells were typically composed of slotted plastic

pipe, surrounded by stone or other aggregate material, that were installed in borings in the

waste mass below the surface of the site. Above the surface of the waste mass, the

extraction well typically has a wellhead to allow for vacuum adjustment and sampling of


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the LFG. The orientation of these wells could either be vertical or horizontal and the

decision to use vertical and or horizontal well will depend on the site-specific factors and

goals of the LFG project. For this project vertical well was chosen as seen below in figure

3.

Figure 3 Showing vertical well

The components of a vertical well included the well piping with perforations or slots at

the bottom portion of the pipe, clean gravel backfill, soil backfill, a bentonite plug and a

wellhead. Polyvinyl chloride (PVC) piping for vertical well construction was sometimes

used, because PVC resists collapsing caused by heat and pressure in deep waste better

than high density polyethylene (HDPE) pipes. However, PVC pipe can become brittle

over time and crack and collapse. For this reason, HDPE pipe may be preferred and also

has been used successfully in vertical wells. A bentonite plug was used to prevent


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infiltration of air from the surface through the well annulus into the well. Bentonite was a

family of clay compounds that expands when wet to serve as an effective seal. The use

of a plastic seal around the well at the waste mass interface with the cover soil can also be

used to inhibit air infiltration. The amount of vacuum that can be applied to a well (and

the overall performance of the GCCS) can be limited by the effectiveness of the seal

between the perforated portion of the pipe and the surface of the waste mass and cover

soil. The depth of the well depends on the depth of waste and will typically terminate at 3

to 5 meters above the base of the waste mass.

Vertical well boreholes range from 20 to 90 cm in diameter and include 5- to 15-cm-

diameter pipe. A minimum borehole diameter of 30 cm and pipe diameter of 10 cm were

recommended. Larger-diameter boreholes and pipe typically increased LFG collection as

a result of the increased surface area. The placement and spacing of vertical wells in a site

depend on various site-specific parameters, including:

Depth of the waste

Depth of the well

Leachate levels

Compaction of the waste

Type of daily cover (if used)

Wellhead Components

Wellheads were placed on above the surface to allow for vacuum adjustment and

sampling of the LFG (see figure 4 below). There were several components of a LFG

wellhead: a vacuum control valve; monitoring ports; and an option for flow


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measurement. The vacuum control valve allows an LFG technician to adjust the

vacuum applied at each individual wellhead. The wellhead was often designed with

one or two monitoring ports so an LFG technician could measure the temperature,

pressure, and composition of the LFG. These ports allow an LFG technician to record

the impacts of well adjustments and to identify potential problems and troubleshoot

errors that may occur in the GCCS. Frequent wellhead monitoring promotes optimal

system operation and allows for effective system maintenance. In addition, wellheads

could include a flow measurement device (for example, an orifice plate or pitot tube)

to measure the differential pressure of the LFG and use those figures to calculate the

LFG flow. The top of the wellhead included a removable cap to access the well for

internal inspection and measure and remove liquids as necessary. High levels of

liquid (leachate) in a well can reduce LFG collection, especially if the liquid level is

above the perforated pipe section of the well, preventing the gas from moving into the

well.

Figure 4 Showing example of a well head

Lateral and Header Piping

Lateral and header piping were installed to transport LFG from the individual wells to the

blower and flare system. LFG piping was designed to accommodate the necessary


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volume of LFG, minimize vacuum loss and provide consistent vacuum to the individual

wells. Lateral pipes connect each well to larger header pipes. Header pipes aggregate the

LFG collected and transported in the lateral pipes. The lateral and header piping system

was designed to accommodate the maximum expected LFG flow rates to minimize future

upgrades if LFG collection continued to increase. Pipe sizing was also considered due to

vacuum loss caused by friction and the avoidance of pipe blockage by allowing LFG flow

to continue despite moderate condensate build up that resulted from sagging and in areas

where waste could settle. LFG piping may be installed above the surface or below the

surface. Table 1 identifies some general advantages and disadvantages for each

approach.

Above Surface Below Surface

Advantages Disadvantages Advantages Disadvantages

Reduced system costs

in areas where

freezing does not

occur, interim or final

cover has been

installed, and

scavengers do not

have access

Increased ability to

inspect, repair and

upgrade the piping

system

Pipes must be protected

against weather effects andmovement from thermal

expansion or contraction,

which may result in more

frequent cracks and weld

separations

More difficult maintenance

of the waste mass surface or

cover (such as grass

mowing)

Can result in lower

operating costs

May be more visually

appealing than

abovesurface piping

More expensive

install

Table 1. Showing advantages and disadvantages of installing LFG Piping above or

below ground surface


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Condensate Management

Condensate refers to the moisture or liquid that was formed when extracted LFG cools.

There were many factors that affected the quantity of condensate generated in a GCCS,

including the LFG temperature and volume. In addition, the climate conditions at the site

also can influence the amount of moisture formed in the LFG. As LFG was collected

from the waste mass, it cools and has a reduced ability to hold moisture in a vapor form.

The condensation that formed could restrict or completely block the flow of LFG in the

piping system. The GCCS was carefully designed to consider condensate management

issues to prevent negative impacts on LFG collection.

The lateral and header systems was designed to facilitate condensate drainage to low

points, where it could be removed from the system by vacuum-sealed sump pumps or

allowed to drain back into the waste mass. Typically, a minimum slope of 3 to 5 percent

will facilitate condensate drainage even if pipe settlement occurs. If drained back into the

waste mass, the condensate low point must include a vacuum trap to prevent air from

being drawn into the header. The trap must provide a sufficient vacuum break to match

the maximum expected applied vacuum on the system (plus a safety factor).

Once the LFG was collected from the waste mass, it was necessary to treat it to remove

moisture and particulates. The removal of moisture and particulates was necessary to

reduce the abrasive and corrosive nature of the raw LFG to protect the blower and ensure

the LFG would burn effectively in a flare or other combustion device. Particulates were

removed through the use of filtration. The most common device for moisture control used

was a moisture separator (sometimes referred to as a knock-out pot), which was a large


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cylindrical vessel that reduced the velocity of the LFG to allow entrained moisture to fall

out of the LFG. A mist eliminator was often used to further remove moisture and other

particulates in the LFG. A mist eliminator could be a wire-mesh or plastic-mesh screen

through which the LFG passes and collects droplets of water that were too small to be

collected by the moisture separator. The wire-mesh screen was subject to potential

corrosion. This system also screens out other particulates that the LFG may contain.

Condensate management system was implemented to pump liquids collected by sumps to

one or more storage tanks to house the condensate until it could be treated, reused or

disposed of. Collected condensate was combined with leachate for treatment or disposal

Blower and Flare Skid

The blower and flare skid was a critical part of the GCCS. The blower provided the

vacuum used to collect LFG from the waste mass. It also provided the necessary pressure

to push the LFG to the flare or to an energy use device. A flare system was used to

combust the LFG and in many cases was required to control odors or mitigate other

environmental or health concerns. The blower and flare system was centrally located near

the LFG collection system. The flare systems was installed away from trees, power lines,

or other objects that could be ignited by the flame or damaged by heat.

Once the LFG has been treated, it then flows to the blower where the vacuum at the inlet

was adjusted to meet the requirements of the GCCS and the outlet pressure of the gas was

adjusted to conform to the requirements of the flare or energy use device. The LFG

typically passes through a metering system to measure the flow rate of LFG being

collected by the GCCS. Basic metering systems included a volumetric flow meter.


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However, a continuous methane monitoring system was implemented to measure the

mass flow rate of methane in the LFG. This continuous monitor was pertinent, if the

SWD site was required to collect LFG.

Flares

There are generally two types of flares: (1) open flares (candle-stick flares), and (2)

enclosed flares (ground flares), as shown in Figure 3-4. Open flares consist of a long

vertical pipe, a burner tip and a flame shroud. Open flares that are properly engineered

and operated may achieve up to 98 percent destruction efficiency and are usually much

smaller than enclosed flares. Open flares can be less costly and easier to install and

operate than enclosed flares.

Figure 4.1 Showing two types of flares

Enclosed flares that are properly engineered and operated may achieve destruction

efficiencies of 99 percent or greater. One significant drawback to this type of flare system

is that it is more expensive to install and operate than an open flare.


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Construction

Once the GCCS was designed (and permitted, if necessary), construction of the system

began. Construction employed proven techniques which ensured a well-built system, and

a quality assurance program was implemented to make sure that the system was built in

accordance with the required design considerations (such as pipe slopes and well depths).

Field engineering decisions was needed to account for unforeseen conditions at the time

of construction. Construction oversight was important to identify potential changes in the

system design needed to accommodate site conditions and to document the as-built

condition of the system.

Construction Techniques

A separate qualified company was identified and hired to provide construction quality

assurance (CQA) to monitor and document the techniques used. The first step in

construction of a GCCS was drilling the vertical wells. It was imperative not to

compromise the containment system when vertical wells were drilled. As the driller gets

set to drill each well, the designated CQA agent monitored and verified the elevation and

depth of the well and confirmed that it matches the construction drawings to avoid

drilling through the base (or liner, in some cases) of the SWD site.

Vertical LFG wells had a diameter of 20 to 90 cm to easily lift waste materials out and

achieve good LFG extraction. A bucket-type auger drill rig was the most desirable type

for drilling in solid waste. This type of drill rig used a large hinged cylindrical bucket

with cutting blades at the base to cut through materials. However, this type of drill rig

was not commonly available in many countries, and a standard auger was also used. In


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addition, some drillers have limited or no experience with solid waste and may not want

to use the more expensive bucket-type auger rig in such applications for fear the rigs will

be damaged. Figure 5 shows a vertical extraction well being drilled with a bucket type

auger.

Figure 5. Showing vertical extraction well digging with bucket auger

Vertical well installation requires planned construction techniques that prioritize the

health and safety of workers. Materials excavated from a borehole was placed upslope so

that any liquids draining from the materials flow back into the borehole to minimize

exposure to liquids and exposed waste. The borehole was covered when drilling was not

active to minimize the potential of workers falling into the borehole.


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Construction Quality Assurance Procedures

CQA was important for proper installation of a GCCS and for documenting the as-built

condition of the system. The design engineer obtained and review available as-built

drawings for the bottom liner system or depth of the waste. As a pre-cautionary measure,

if as-built drawings are not available, the design engineer would review system

construction or permit drawings for the bottom liner. Based on available drawings and the

desired location of each well, the depth of waste was calculated for each well along with

a corresponding calculation for the appropriate well depth. These construction drawings

should be reviewed by a second qualified engineer to double-check the well locations,

waste depths, elevations, and calculations.

Before construction began, a professional surveyor stake out each well and collection

piping routes. The surveyed elevations and well identification numbers was be recorded

(and assigned) and written on stakes positioned at each well location. The recorded

survey data included the horizontal and vertical data for each well stake and collection

piping grade stake. In the event one or more of the well location stakes was removed or

destroyed, the well locations would be resurveyed before the well location stakes were re-

established. The surveyor was not allowed to guess the location and re-establish the well

location stake, based on inaccurate survey data which could cause improper or

insufficient pipe slopes or a penetration of the bottom liner.

Survey data was provided to the design engineer for comparison to the existing

construction drawings and revised and updated as needed. The revised construction

drawings submitted to the driller. It was good practice to have the design engineer

approve the final construction drawings. The CQA monitor reviewed the construction


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drawings with the driller, landfill owner, general contractor, and any other appropriate

parties to make sure all agree to the drilling plan. It was also good practice for the CQA

monitor and contractor to walk the entire SWD site with the driller to identify all well

locations and confirm that the drill rig and support equipment are capable of accessing

the well locations. As the wells and collection piping were being installed, it is important

that either the design engineer or the CQA monitor keep accurate records of the pipe

depth, pipe location, and the location of special fittings such as tees that mark where a

lateral pipe was joined to the header. Other important structures such as condensate traps

or condensate sumps were documented on the as-built drawings to include any deviations

from the design plan. As-built drawings were developed to document the locations of

wells, piping, and important structures.

General Operating Considerations

Generally, a GCCS operates on a continuous basis. However, site conditions

continuously change and the rate of LFG collection will vary temporally and across

locations within the waste mass. Changes to site conditions occur for various reasons,

such as:

Air intrusion through cover soil Rate of waste disposal and age of the waste Changes in atmospheric pressure Precipitation and moisture in the waste mass Variations in waste characterization.


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Compaction levelThese changes require periodic monitoring and adjustment of the vacuum applied to each

well to maintain or increase collection efficiency, prevent excessive vacuum application,

minimize problems associated with LFG emissions or potential migration, and to

optimize energy use project operations. Monitoring can also help detect undesirable

subsurface combustion that can result if excessive vacuum is applied to the wellfield

(introducing oxygen into the waste mass). Monitoring was conducted adequately to

promote optimal system operation and to allow for effective system maintenance.

Generally, system monitoring involves examining LFG conditions at the wellheads and

the waste mass surface. Typical wellhead monitoring parameters include:

Volumetric flow rate Methane concentration Oxygen concentration Carbon dioxide concentration Balance gas concentration (typically Nitrogen (N2))


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EVALUATION

Landfill gas quantity

LFG was generated as a result of physical, chemical, and microbial processes occurring

within the waste. Due to the organic nature of most waste, the microbial processes

governs the gas generation process (Christensen, 1989). These processes were sensitive

to their environment; therefore, a number of natural and artificial conditions affected the

microbial population and thus the LFG generation rate. Short-term studies carried out on

full-size landfills using data from LFG extraction tests indicated a range of LFG

generation between 0.05 and 0.40 cubic metres (m

3

)

of LFG per kilogram (kg) of waste

placed into a landfill (Ham, 1989). The mass of waste accounts for both solid materials

(75 to 80 percent by mass) and moisture (20 to 25 percent by mass). This range was a

function of the organic content of the waste that was placed into the landfill.

It was important to note that LFG generation occurred in an anaerobic (no oxygen)

condition, and thus any natural or artificial conditions that move the process to an aerobic

condition will affect generation of LFG. It was also important to note that LFG

generation was not instantaneous; any amount of waste that was brought to a landfill


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would undergo a set of processes that have been well-characterized by Farquhar and

Rovers (1973), as shown on Figure 6.

As indicated on Figure 6, the first phase, aerobic decomposition, occurs immediately

after the waste has been placed, while oxygen was present within the waste. Aerobic

decomposition produces carbon dioxide, water, and heat until such time as the oxygen

present in the waste is consumed. The next stage was the anoxic, non-methanogenic

phase where acidic compounds and hydrogen gas were formed and while there was

continued carbon dioxide generation; generally, this was a hydrolysis and acetogenic

process. Substances produced during this stage as larger molecules were broken down to

smaller chains include ammonia, carbon dioxide, hydrogen, water, and heat, all of which

work to displace any residual oxygen and nitrogen that may reside in the waste (SEPA,

2004). The third phase was the unsteady methanogenic phase; during this phase, the

carbon dioxide generation began to decline because waste decomposition moved from

aerobic decomposition to anaerobic decomposition. Anaerobic decomposition produces

heat and water, but unlike aerobic decomposition, it also produced methane.

Methanogenic bacteria were active during this stage, utilizing the byproducts of the

previous stage to produce methane.

During the fourth phase, methane was generated at a concentration between 40 and 70

percent of total volume (McBean, 1995); in this stage, the processes responsible for the

generation of methane was generally stable. Typically, the waste in most landfill sites

would reach the stable methanogenic phase within less than 2 years after the waste has

been placed, although it should be noted that environmental conditions were also an


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important factor in this equation. Environments with high moisture and temperature, and

where moisture was able to infiltrate readily into the waste, will show a generally shorter

timeframe for reaching the stable methanogenic phase. In extreme conditions, the

timeframe for reaching this stage can be on the order of months. LFG may be produced

at a site for a number of decades dependent on landfill conditions and type and age of

waste, with emissions continuing at declining levels from the date of placement. This

could be seen in Figure 6, which shows a typical profile for LFG generation at a site.


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Figure 6 Showing landfill gas generation pattern


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Waste Composition

Waste composition was the most important factor in assessing the LFG generation potential and

total yield at a site. The maximum potential volume of LFG was dependent on the quantity and

type of organic content within the waste mass (Environment Canada, 1996), since the

decomposing organic wastes were the major source for all LFG produced. The link between

waste composition and LFG generation was very clear. Inorganic and inert wastes will produce

little or no LFG; more organic wastes will produce greater amounts of LFG on a per unit mass

basis, but it was important to keep in mind that it was the actual organic fraction of the waste that

produces LFG. Highly-organic wastes such as food wastes were able to produce LFG, but also

comprise largely water, which inherently does not produce LFG but will aid the rate of LFG

evolution. The same consideration was true of the rate of generation. The same waste mix and

mass placed in an arid environment versus a humid environment contains the same overall

potential for generating LFG; however, the relative rate of this generation will occur at a more

ready pace in the more humid environment if moisture is allowed to infiltrate into the landfill.

Excess amounts of moisture, however, will not continue to support this effect.

The shape gas generation curve may be most significantly-altered, rather than the total potential

gas generation. This point was of particular concern when designing LFG management systems,

and in particular, when assessing the viability of LFG utilization.

Moisture contentThe amount of moisture within a landfill was considered to be one of the most important

parameters controlling gas generation rates; to some extent, the amount of moisture may affect


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the ultimate methane generation potential of the waste, but the primary effect was related to the

rate of generation. See Figure 7 for typical gas profiles for both a "dry" and a "wet" landfill with

the same waste composition and deposition rate; in the latter case, the gas generation profile was

more peaked and drops off to lower levels at a faster rate. Understanding the relevant moisture

conditions and water balance of a landfill was important in predicting the amount of LFG

generation and thus was a part of the design basis for LFG collection systems. It was also noted,

that waste has its own inherent moisture when it reaches a landfill, so the moisture content

consideration was not solely related to environmental conditions. Generally, for municipal solid

wastes that include food wastes, etc., sufficient moisture was available in the waste to initiate the

methanogenic cycle.

Moisture provides the aqueous environment necessary for gas generation and also serves as a

medium for transporting nutrients and bacteria. The moisture content in the landfill was strongly

influenced by climatic conditions (temperature, rainfall, etc.), initial moisture content of the

waste, and specific landfill design such as type of base liner, type of leachate collection system,

type of cover, and programs such as bioreactor/rapid stabilization with or without leachate

recycling. Landfills are typically constructed and filled in a sequential layered pattern. This

factor was important in understanding how moisture moves into and through the waste. The

layering effect tends to result in substantially different flow characteristics for the movement of

leachate and infiltration of water into the landfill, and may have an effect on LFG movement

within the waste. It was possible to somewhat control the rate of LFG generation through

engineered waste management systems.


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Figure 7 Showing LFG generation based on moisture content


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CONCLUSION

LFG was produced at the Beetham landfill site containing decomposable organic wastes. The

major constituents of LFG were methane and carbon dioxide, which were by-products of the

biological decomposition of organic material. The main objective of this project was to find an

alternative solution to manage the increasing levels of garbage disposal at the Beetham Landfill

and preventing it from reaching full capacity, resulting in closing down the entire landfill

indefinitely. The redesigning of the Beetham Landfill received a unanimous approval from all

stakeholders involved and this prompted further investigation into the feasibility of the project.

After all research and environmental audits were conducted, approval from various municipal

and State agencies were sought after and the necessary permits to commence the project were

granted. This project was implemented in stages over a period of 12-15 months at a cost of 1.2

million USD. Some of the benefits of the project were: provide employment to Beetham

residents and the population nationwide, provide a source of renewable energy for generation of

electricity as well as contribute to the nations GDP.


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RECOMMENDATIONS

Based on the foregoing, the following recommendations are offered:

To have continuous internal system audits in order to ensure compliance to all currentoperating regulations are met.

To have periodic training and development for employees Look into alternative commercial uses of LFG for example, biofuel for cars. Burn all LFG that is produced. For instance, combusting LFG in an engine, a turbine, or

simply in a flare has tremendous benefits in terms of reduced toxicity and reduced

greenhouse gases. Sixty one percent of LFG is generated at landfills with no collection

system and at least 25 percent of LFG at landfills with collection systems simply

escapes. Collecting all of this gas and burning it -- preferably for energy, but at least in a

flare -- should be a priority nearly equal to avoiding the construction of new landfills. As

a result, this would contribute to land conservation.

Use LFG for energy production. While there are instances where the use of LFG forenergy can increase the amount of certain pollutants, the balance of benefits is in favor

of using LFG for energy. Generally turbines are cleaner than engines, though less

efficient. However the benefits of LFG are greatest if we also increase air pollution

regulations and energy efficiency so that we displace coal plants instead of gas plants.


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REFERENCES

(n.d.). Availble at :LiveSmart BC. 2008. Available at: http://www.livesmartbc.ca.

Barlaz, R. K. (1989). Measurement and Prediction of Landfill Gas Quality and Quantity in Sanitary

landfilling. Process Technology and Enviromental Impacted, 155-158.

British Columbia Ministry of Environment. (2008). Landfill Gas Management Regulation. Richmond:

Conestoga-Rover and Associates.

E.A.Mc Bean, F. R. (1995). Solid Waste Landfill Engineering and Design.New Jersey: Prentice Hall.

Environment Canada. (2009). National Inventory Report Green House Gas Sources and Sinks in Canada.

Richmond: Conestoga-Rover and Associates.

Intergovernmental Panel on Climate Change (IPCC). (2007). Fourth Assessment Report: Climate change .Available at :http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html. .

Scottish Environment Protection Agency. (2004). Guidance on the management of Landfill gas.SEPA.

Solid Waste Association of North America (SWANA). (1997). Landfill Gas Operation and Maintenance

Manual of Practice.

Thomas, C. H. (1989). Basic Biomedical Processes in Landfills in Sanitary Landfilling: Process Technology

and environmental impacted.New York: Academic Press.

US Environmental Protection Agency. (2006). Global Migration of non Carbon dioxide Greenhouse gases.

USEPA.

http://www.nrel.gov/docs/legosti/fy97/23070.pdf.
http://www.nrel.gov/docs/legosti/fy97/23070.pdfhttp://www.nrel.gov/docs/legosti/fy97/23070.pdfhttp://www.nrel.gov/docs/legosti/fy97/23070.pdfhttp://www.nrel.gov/docs/legosti/fy97/23070.pdfhttp://www.nrel.gov/docs/legosti/fy97/23070.pdf


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APPENDICIES

Appendix A: Showing Completed Gantt chart

Task name First quarter Second quarter Third quarter Fourth quarter

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Investigation

Consultation

Acquiringpermits

Procurement

Implementation

Evaluation

Appendix B: Showing request for approval to hire


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ECO - DRIVE ENGINEERING LIMITED

Request for Approval to Hire

Applicant Information

Requisition

Number: 1234587 Date:

Applicant Name:

Last First .I.

Job

Title:

Part Time Full Time Permanent Temporary

Replacement

New Position

Hourly

Exempt

Proposed Starting

Salary: Start Date:

Supervisor:

Department

:

Description of Duties:

Additional Comments:

Supervisor Signature Date

Approval to Hire

ApprovedSalary:

ApprovedClassification:

Department Manager Signature Date

Confirmation of Offer

Offer Extended


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By:

Status of Offer: Accepted Declined


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Appendix C: Showing Tendering form

To : [Institution]

[address]

[Date]

Dear [insert Sir/Madam or name]

Tender Ref: [insert internal reference number]

Tender for [insert short description of requirement and, if appropriate, relevant time period]

1. I/We have read the information provided in your Invitation to Tender and subject to and upon

the terms and conditions contained in [Document reference] - Contract Documents, I/We offer to

supply the [requirement] described in the contract documents in such manner as may be required.

2. Terms and Conditions. I/We agree that this tender and any contract which may result, shall be

based upon the documents listed below, and that the Buyer is the [give the legal entity of your

institution (eg the University Senate/Court of the institution)].

2.1 The contract documents as shown in the Invitation to Tender.

2.2 The prices to be inserted in the Contract shall be those shown in [document name] of our

tender; or, if the Institution selects an alternative proposal from [document name], then the prices

shown in [document name] pertaining to that proposal.

2.3 In other sections of the Contract information provided in [document name] - AdditionalInformation Required by the Institution, will be included.

2.4 Any qualifications set out by us in [document name] - Qualifications, shall also apply,

although we understand that making a qualification may result in your disregarding our tender in

total.

3. In [document name] - Alternative Proposals, I/We include alternative proposals, together with

costings, which we feel might provide better value for money for the Institution than the required

proposal. I/We do not wish to submit alternative proposals in Appendix C - Alternative

Proposals *

* Delete as appropriate

4. The prices quoted in this Tender are valid until [state date given in section 2.3 of Conditions of

tender submission] and I/We confirm that the terms of the Tender will remain binding upon

me/us and may be accepted by you at any time before that date.


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