As the nation becomes more urbanized, sites once considered remote are now located in areas increasingly ripe for development or redevelopment.
ABSTRACT
Increasing urbanization in the US is leading to development or
redevelopment of lands adjacent to solid waste facilities and these lands are
being considered for residential communities and commercial projects. Thus, the
potential for nuisance complaints against the pre-existing solid waste facility
operations has become an increasing reality. The objective of this study was to
develop a methodology to gather scientific and quantifiable data related to
potential nuisances caused by landfills to determine setbacks and buffer zones
near landfill and transfer station operations. Appropriate recommendations for
these setbacks were made from case studies conducted at two landfills in
Florida. The study involved measurements related to odor, noise, litter and
dust. Impact on housing prices was also evaluated by analyzing publicly
available house price data. In this study volatile organic compound (VOC)
concentration was used as a surrogate measure for gaseous impacts.The
mass flux of VOCs was measured on the landfills using the dynamic flux chamber
method. The ultimate purpose of flux measurements was to provide input data for
dispersion modeling to analyze the extent of odor impact around the landfills,
which is outside the scope of this study. Ambient measurements were also made
around Landfill A for validating the dispersion model. Although there are no
significant health and odor impacts caused by the landfill, higher background
concentrations extend 1.2 km–1.5 km from the active landfill cell center on the
southeast side of the landfill. Litter from roadsides around the landfills was
collected and catalogued based on size and material type. Litter count per site
obtained for both landfills was less than the 2001 and 2002 statewide counts.
The difference was statistically significant. Noise measurements were made at
landfills during waste-to-energy (WTE) operations and landfilling. Based on
average measurements obtained at various distances from WTE facility and
landfilling activity, and considering EPA recommended noise level of 55 dB(A)
for a quiet neighborhood, a set-back distance of 1.6 kilometers to1.9 kilometers
was recommended. Impact on house prices near the landfills was evaluated for
four landfills in Florida. Analysis showed that three out of four landfills
significantly affected the house prices within a range of 0.6-km to 0.8-km from
the edge of the landfill cell. Dust measurements were made at Landfill B using
particulate samplers, quantifying the dust associated with landfilling. Measured
values were below National Ambient Air Quality Standard (NAAQ) for PM10.
Finally, recommendations were developed to mitigate some of these nuisances.
Introduction
As
the nation becomes more urbanized, sites once considered remote are now located
in areas increasingly ripe for development or redevelopment. In order to site
solid waste facilities, local governments have installed such public works
infrastructure as roads and utilities, reducing the costs for owners of adjacent
parcels. Consequently, land adjacent to solid waste facilities is being
considered for development such as residential communities and commercial and
industrial projects. Thus, the potential for nuisance complaints against the
existing solid waste facility operations has increased in many areas of the
nation. The most widely used measure of the magnitude of a facility nuisance
problem is the number of complaints it receives. Most of the nuisance complaints
received by the landfills are related to odor, noise, litter, and birds. These
issues are a function of distance from the landfill, and in reality most of
these complaints are received from the people living very near to the landfill.
People living near the landfill are mainly concerned about the change in their
property values compared with the properties farther away from the landfill.
There
have been some instances in recent years in which public and private
owners/operators of solid waste facilities have been forced to close their
facilities prematurely because of urban infilling, resulting in loss of valuable
solid waste capacity and increased cost for solid waste disposal (Rogoff et al,
2006). Development of properties adjacent to solid waste facilities will become
a significant problem for solid waste managers in the years ahead. Therefore,
the objective of this research was to develop methodology to gather scientific
and quantifiable data to support setback distance and buffer zones near
landfills. As an example of this recommended approach, appropriate
recommendations for these setbacks were made from two case studies.
Backgrounds
Most
of the research on nuisance issues near landfills is related to evaluating the
overall impact caused by the landfill. In many studies overall impact was
evaluated by conducting a community survey in the neighborhood of the landfill
and analyzing the results statistically.
Furuseth and Johnson (1988) studied the attitudes of people living
within 5 km of a sanitary landfill in North Carolina. The primary goal of this
study was to assess the role distance to a landfill played in individual
perception and concern. Among the impacts cited noise, landfill traffic, litter
from garbage trucks, appearance of the landfill, and property devaluation raised
the greatest concerns. Approximately 35% of respondents were concerned about the
traffic problem, 31% about garbage truck litter, and 21% about traffic noise
problem. About one-third of the respondents felt that the landfill adversely
affected the value of their property. Further analysis showed that the effects
that were sensory-related, such as landfill noise, odor, litter, and dust, were
strongly influenced by the distance from the landfill. Property devaluation was
the only nonsensory effect influenced by the distance from the landfill.
Finally, this study recommended better understanding of these effects around the
landfill so that buffer distances can be more appropriately defined and
efficient local decisions can be made that are fair to citizens and land use
planners.
Odors
from landfills are of particular concern for residents living near landfills and
have been the subject of several studies. Bedogni and Resola (2002) developed a
methodology to evaluate odor impact of a solid waste landfill in the northern
part of Italy. The methodology integrates two different approaches: monitoring
data and modeling to simulate the impact of odor emissions. In this study, the
CALPUFF dispersion model was used to carry out the evaluation. The validation
compared the gas and odor concentrations measured at five points outside the
landfill with the corresponding values estimated by the model. The results of
the validation procedure showed a good agreement with the experimental data
concerning methane emissions but overestimated the concentration of odorous
gases. Finally, this study focused on methodology used and its importance as a
decision tool for odor-impact situations.
Nicolas et al (2005) studied the estimation of odor-emission rates
from landfill areas using the sniffing team method. The odor was detected by the
sniffing team at various points around the landfill by moving in a zigzag manner
around the plume axis. The meteorological situation was simultaneously recorded.
Then, a bi-Gaussian model was used to simulate the perception of the odor.
McGinley (1998) studied the various odor-quantification methods and practices at
MSW landfills. In this study, 10 methods were reviewed that were commonly used
by MSW landfills and regulatory authorities.
Reichert et al (1991) studied the impact of five municipal landfills
on surrounding residential property values in Cleveland, OH. In this study, a
total of 2,243 market sales was analyzed using regression analysis, and the
results were mixed. In a similar study done by Schulze et al (1986) three
different California city housing markets were analyzed for potentially
hazardous landfill effects. The study found significant results for one region
for houses within 300 meters of the landfill site.
Materials and
Methodology
The
methodology adopted involved measuring various quantifiable parameters related
to nuisance complaints typically received by landfills at two sites (Landfills A
and B) in Florida. The quantifiable parameters that were measured were volatile
organic compounds (VOCs) mass flux rate, noise, litter, and dust.
Landfill A is located in one of the most densely populated counties
of the state. Approximately 800 to 1,000 vehicles arrive at Landfill A each day,
and in 2006 the landfill received approximately 284,800 megagrams of solid
waste. This facility consists of a waste-to-energy (WTE) facility, an ash
processing facility, a municipal solid waste (Class I) landfill and a
construction and demolition debris (Class III) landfill. Ash from the ash
processing facility is used as landfill cover.
When
the area was chosen for construction of a solid waste facility, the surrounding
land was undeveloped. The landfill began its commercial operation in 1979 and
construction of the WTE plant started in 1980. During this time, over the
objection of the county, the city in which the landfill is located approved the
zoning for construction of a residential community containing several hundred
homes directly west of the active landfill. Also during the 1980s and 1990s, as
permitted by the zoning regulations, the surrounding area continued to develop
commercially.
Landfill A started logging complaints related to odor, noise, litter,
and birds, in 2004 from the residential community west of the landfill. The
number declined during later years. All the complaints were received from the
houses that are nearest to the landfill.
Landfill B is located in the central part of Florida and started its
operations in 1978. It has a total footprint of 0.98 km2. It is a Class
I inward-gradient landfill with a natural clay liner and has a total design
capacity of 34,405,000 cubic meters. Gas recovery and leachate removal systems
were installed. In 2006, the landfill received 308,500 megagrams of solid waste
and 48,300 megagrams of yardwaste. Landfill B is surrounded with highly dense
tree growth and the nearest residential housing is at least 600 meters away from
the landfill. Therefore, they have never received complaints related to any of
the nuisance issues.
VOC Flux Measurement—People in
communities near landfills are often concerned about odors emitted from
landfills. Potential sources of landfill odors include sulfides, ammonia, and
certain non-methane organic compounds (NMOCs), if present at sufficiently high
concentrations. A landfill system has a strong potential to produce and release
an excessive amount of organic compounds into the atmosphere (Zou et al., 2003).
Also, Kim et al (2005) characterized malodorous sulfur compounds in landfill gas
and found that hydrogen sulfide is the main odor-causing component. Further,
they found a strong correlation between hydrogen sulfide and VOCs for several of
the landfill sites. VOCs are composed of methane and some NMOCs (Kreith, 1995).
NMOCs include saturated and unsaturated hydrocarbons, acidic hydrocarbons,
organic alcohols, halogenated compounds, aromatic compounds, and sulfur
compounds (Keller, 1988). Although NMOCs account for less than 1% of total VOCs,
they can cause significant health impacts (Zou et al., 2003), and alkyl
benzenes, limonene, certain esters, and organosulfur compounds are responsible
for undesirable odor. Hence, in this study, VOC concentration was used as a
surrogate measure for gaseous impacts.
The
mass flux of VOCs was measured on the landfill using the flux chamber method.
The concentration of VOCs in the exit gas from the flux chamber was measured
using a flame ionization detector (FID). In this methodology, the dynamic flux
chamber method was used, since it is the most accurate method for determining
emission rates from the landfill (Cooper et al, 1992). The ultimate purpose of
flux measurements is to provide input data for dispersion modeling to analyze
the extent of odor impact around the landfill, which is outside the scope of
this study.
The
operational procedure was adopted from Walker (1991), Rash (1992), and Eun
(2004). Random sampling points were selected on the landfill to place the flux
chamber. The flux chamber was sealed along the edges using a bentonite slurry
and a flow meter was connected to the inlet. Air was supplied at a constant flow
rate into the flux chamber. A portable MicroFID from Waltham, MA–based Photovac
Inc. was used to measure the concentration of VOCs. The MicroFID uses a hydrogen
supply and the oxygen from the sample air to support combustion. Measurements
were made at the exit port using the MicroFID at constant intervals until a
steady-state condition was achieved. At steady-state, the concentration of VOCs
at the exit port was recorded. The emission rate at the sampling point was
calculated using Equation 3.
Where
F is
the emission flux rate measured for sampling point (mg/m2-min)
C
(mg/L) is exit VOC concentration in mg/L as carbon
Q is
the flux chamber sweep air flow rate in L/min, and
A is
the enclosed surface area (0.19 m2)
Litter Survey—Most
litter surveys are focused on roadsides because they are easy to access and
measurements are straightforward. The methodology followed for the litter survey
around Landfills A and B was similar to that developed by the Florida Center for
Solid and Hazardous Waste Management (FCSHWM 2002). The primary goals of the
litter survey around Landfills A and B were to quantify the litter and identify
the composition of the litter.
At
both Landfills A and B, litter is collected five days per week as part of their
daily operations. Roads around the landfills were selected that are accessed
daily by trucks and trailers carrying waste to the landfill. Litter is collected
on a selected road, and when the collection is completed, litter collection on
another selected road will be started.
For
Landfill A, litter collection is done on the selected roads around the landfill
in five days and the procedure is repeated every week. Litter collection around
Landfill A for this survey started on April 16, 2007. Litter collected on
different roads was stored in bags with nametags identifying where they were
collected. Collection of litter was completed by April 20, 2007. Overall, 40–45
bags of litter were collected, and litter was counted and catalogued on April
20, 2007. The procedure was repeated the next week when 35–40 bags were
collected. Collected litter was counted again on April 27, 2007.
Landfill B has only one approach road, and litter collection on this
road is done three to four times every week by landfill personnel. Each time,
four to six bags of litter is collected on this approach road. Similar to
Landfill A, collected litter near Landfill B was counted and catalogued. Since
litter is removed continuously from the selected roads around each landfill,
this approach captures the steady-state litter that has accumulated between the
scheduled collections.
Litter collected on the roadsides around the landfills was counted
and categorized based on material type. Similar to the methodology followed by
FCSHWM (FCSHWM 2002), litter was first categorized by size as small litter (area
< 26 cm2) and large
litter (area > 26 cm2) and then based
on material type as paper, plastic, glass, aluminum, and steel, mixed and
composite. This classification allowed comparison of the litter-count values
obtained around Landfills A and B to the values obtained by the FCSHWM in
statewide surveys, which would represent background litter. FCSHWM statewide
surveys measured litter that had accumulated over a relatively long period of
time. The FCSHWM surveys capture a steady-state condition balancing litter
accumulation and degradation. In this study, the amount of litter present on
road segments represents a steady state established between accumulation and
regular litter collection by landfill personnel.
Impact on House Prices—The
effect of certain land uses on residential property values has long been of
interest in the public policy arena. In the real estate market, people are
willing to pay higher prices for sites that are not affected by nuisances than
for sites affected by nuisances (Crecine et al, 1967). Past research showed
mixed results regarding impact of landfill on nearby residential property values
(Reichert et al, 1991). Statistical approaches were adopted in previous studies
to analyze the impact of landfill on house prices.
In
this study, impact on house prices near the landfill was evaluated using market
price data available from a public Web site, www.zillow.com. In order to evaluate the impact, data
regarding a 10-year (1997–2007) percentage change in house prices was analyzed.
It is recognized that there are some limitations to this public source, however
we believe that the trends are consistent and worth reporting. A more accurate
assessment could be made using local tax records.
Noise and Dust Measurements–These
studies were performed by the UCF CEE Community Noise Lab. Typical daily sounds
range from 40 dB(A) (very quiet) to 100 dB(A) (very loud). The EPA states a goal
for community noise levels of 55 dB(A). Sound-level meters Cesva 310 from
Scantek Inc. (Columbia, MD) and Metrosonic dB308 (Norcross, GA) were used to
measure noise. A receiver height of 1.5 meters was used at all microphone
locations. All receivers were located at least 3.5 meters from any reflecting
source, such as a building or a wall. Key, or reference, receivers were located
as close as possible to avoid unwanted interferences.
At
Landfill A, the first set of measurements involved measuring noise levels
associated with typical WTE facility activity and the second set of noise levels
associated with landfilling of unburned waste were both made when the WTE
facility was down for maintenance. For both cases, background noise levels were
measured by setting up sound-level meters far away from the source. Landfill B
noise measurements were mainly made to capture the noise levels associated with
equipment used on the landfill and then measurements were made to capture the
noise levels at various locations on the landfill.
Dust
measurements were also made on Landfill B. Dust is generated from the landfill
mainly from landfilling activity and from trucks/trailers traveling around the
landfill while moving the waste. Measurements were made by setting up
particulate samplers in upwind and downwind locations relative to the
landfilling activity. Particulate samplers were designed to collect particulate
matter smaller than 10 microns. A 38-elemental breakdown and analysis of the
dust samples collected was done by the Oregon-based Chester LabNet.
Results and Discussion
VOCs Mass
Flux Results—Flux measurements for Landfills A and B were conducted from
December 2006 to June 2007. Most of the trips were made when the forecasted
weather was partly cloudy. Occasionally adverse weather conditions were
encountered during the measurements, such as rain and heavy wind, and the
measurements were stopped. Most of the flux measurements were made between 11
a.m. and 5 p.m. The site weather conditions and landfill visit dates are
recorded in Table 1. According to EPA users guide (Kienbusch, 1986) the minimum
number of samples to be measured is given by Equation 4.
Using the GPS and ArcGIS software, the calculated area
available for measuring the gas emissions on Landfill A was 137,000 m2. Based on the
area available and equation 4, the minimum number of samples required was
approximately 40.
Calculation of available area on Landfill B
was difficult because of its irregular surface profile, however, since the
footprints were similar; it was assumed that the area available for measurements
was also similar. To confirm this similarity, the same distance between the
samples was maintained for Landfill B.
Flux data were collected at Landfill A from
December 2006 to April 2007. All the measurements were made using the dynamic
flux chamber method. Overall, 38 measurements were made on Landfill A, out of
which 14 measurements were below detection limit. Locations of flux measurements
are shown in Figure 1. Emission rates measured on Landfill A ranged from below
detection limit (BDL) to 47 mg/m2-min and a mean
emission rate of 2.37 mg/m2-min (2) was
obtained.
Flux
data were collected at Landfill B from May 2007 to June 2007. Similar to
Landfill A, measurements were made using the dynamic flux chamber method. A
total of 36 measurements was made on the landfill, out of which 18 measurements
were BDL. Locations are shown in Figure 2. Emission rates measured on Landfill B
ranged from BDL to 40 mg/m2-min and a mean
emission rate of 4.59 mg/m2-min (2) was
obtained. The flux from most of the locations where measurements were made that
had intermediate cover consisting of a mixture of mulch and dirt was BDL. Areas
with soil cover only had emissions in the range 15 to 40 mg/m2-min.
Table
2 provides a comparison of VOC measurements conducted on Landfills A and B. It
can be observed from Table
2 that Landfill B has 94% higher emissions than
Landfill A. Table 2 also presents the other characteristics of Landfills A and B
VOC emissions.
A
number of researchers (Barry, 2003; Borjesson et al., 2000; Cardellini, 2003;
Paladugu, 1994; Rash, 1992; and Walker, 1991) have reported methane flux rates.
These rates ranged from 0.253 to 4300 mg/m2-min. VOCs
measured by the MicroFID are composed of methane and NMOCs. In the absence of
site-specific data, the value recommended for NMOC concentration by the EPA is
8,000 ppmv (0.8 % by volume) (EPA, 1999) and for methane 50 % by volume (EPA,
1997). As can be seen, methane concentration is significantly greater than NMOC
concentration. Therefore, for the purpose of this evaluation, methane
concentration is assumed to be approximately equal to VOC concentration and the
mean flux rates of methane on Landfills A and B are within the range of emission
rates reported in the literature.
It is
important to note that the flux rates measured were assumed to be constant over
time. In reality, however, not only the total concentration of VOCs but also the
relative composition of various components of VOCs will vary with time (Kim et
al 2005).
Ambient measurements were made around Landfill A on February 9, 2007.
These measurements will be used to validate dispersion model results by
comparing the model results with ambient data. Weather data were also collected
during the same time on the surface of the landfill. Figure 3 shows the contour
map with ambient measurements and Table 3 provides the concentration range.
The
ambient measurements were made around the landfill using the MicroFID.
One-minute averaging time was used for measuring the concentrations. The
prevailing wind direction during the measurements was from northwest. As would
be expected, highest off-site concentrations were observed southeast of the
landfill as shown in Figure 3.
Some
of the NMOC constituents such as alkylbenzenes and limonene, along with hydrogen
sulfide, are dominant odor sources (Zou et al, 2003). Although there are
negligible health impacts caused by the VOC emissions from the Landfills A and
B, the constituents of NMOCs and hydrogen sulfide can be responsible for causing
offsite odors. To evaluate offsite odor impacts, NMOCs and hydrogen sulfide were
estimated from VOC data.
The
highest VOC concentration, 6.7 ppm, was observed on the southeast side of the
landfill. VOCs measured by the MicroFID are composed of methane and NMOCs. In
this analysis, the NMOC-to-VOC ratio is considered equal to the NMOC-to-methane
ratio. Therefore, the ratio of NMOC to VOC concentration in landfill gas is
0.016. Using this ratio of NMOC to VOC, the highest NMOC concentration would be
0.11 ppm. Most of the NMOC gas components have odor-detection thresholds higher
than 0.11 ppm (ATSDR, 2001) except dicholoroethylene, which has an odor
threshold of 0.085 ppm. Hence, it is unlikely that there were offsite odor
impacts due to VOCs.
Using
a typical concentration of hydrogen sulfide of 35.5 ppmv (EPA, 1990), the ratio
of hydrogen sulfide concentration to methane concentration in landfill gas is
8×10-5. Again, since
VOCs are mainly composed of methane, the hydrogen sulfide–to-VOC ratio is
assumed to be 8×10-5 as well.
Therefore, the highest hydrogen sulfide concentration obtained would be 0.5 ppb,
which is less than the odor threshold for hydrogen sulfide (0.5–10 ppb). Hence
it is unlikely that offsite odor impacts occur due to hydrogen sulfide.
Although there are no significant health or odor impacts caused by
the emissions from the landfill, it can be observed from Figure 3 that ambient
concentrations of VOCs on southeast side of the landfill are higher than the
background (northwest) concentration. These higher concentrations extend 1.2
km–1.5 km from the active landfill cell center on the southeast side of
landfill. Ambient air measurements could not be made around Landfill B because
of the dense tree growth around the landfill.
Litter Survey Results—Litter
surveys were performed around Landfills A and B following a procedure similar to
Florida Center for Solid and Hazardous Waste Management (FCSHWM) (FCSHWM 2002).
Accumulated roadside litter was collected around the landfill and counted after
sorting was done based on size and material. The length of the roads from which
litter was collected was obtained using ArcGIS software. Similar to FCSHWM
methodology (FCSHWM 2002), counts per site were obtained by finding the litter
count per 100 meters of road length.
Litter was collected on 10 selected roads in five days around
Landfill A by the landfill personnel, and the procedure is repeated every week.
In this study, collected litter on all selected roads was counted and
categorized for two collection rounds. Litter count obtained was normalized to
road length. Average litter count values were obtained by averaging the values
obtained in two collect rounds. Table 4 presents the results of the litter
survey around Landfill A.
The
average values of litter count normalized to road length for the roads around
the landfills are less than the FCSHWM 2001 and 2002 statewide surveys, as shown
in Figure 4. The coefficient of variation (COV) for Florida Centers 2001 and
2002 statewide surveys was in the range of 8.5% to 9% (Florida Litter Study
2002). The COV for the data collected around landfill A was relatively high
(70%–90%). In this study, the maximum litter that accumulates around the
landfill was measured and was found to be less than the FCSHWM 2001 and 2002
statewide surveys. Analysis showed that the difference between the litter count
values obtained from the FCSHWM 2002 statewide survey and around Landfill A was
statistically significant at 5% level of significance.
Collected litter around Landfill A was also categorized based on
material type. Results are shown in Table 5. From Table 5 it can be observed
that paper and plastic constituted more than 80% of the total large litter
items. Paper and plastic are the material categories having lower density
compared with other material categories. Hence, a higher percentage of paper and
plastic might be due to litter blowing from the trucks and trailers arriving at
the landfill. Occasionally, on some of the roads near the landfill, trash bags
filled with household waste were collected that presumably fell from the trucks
carrying waste to the landfill.
There
is only one approach road for landfill B that is accessed by trucks and trailers
carrying the waste to the landfill. Litter collected on this approach road by
the landfill personnel was counted and categorized. The procedure was repeated
two times, and average values of large and small litter counts were obtained. It
can be seen from Figure 5 that for Landfill B the accumulated litter is
negligible compared with FCSHWM 2001 and 2002 statewide surveys. Statistical
analysis has not been done for Landfill B because of the small number of counts.
For this purpose, a t-test was done to compare means.
Large
litter collected on road segments around Landfill B was classified based on
material type and compared with the FCSHWM statewide surveys as shown in Table
5. It can be observed from Table 5 that, in the statewide litter surveys
conducted by FCSHWM, mixed and paper were more than 50% of total large litter;
whereas, in the litter surveys around Landfill B, paper and plastic constituted
more than 80% of total large litter. Similar to Landfill A, a higher percentage
of paper and plastic might be due to litter blowing from the trucks and trailers
arriving at the landfill.
Property Values Results—Landfill
A is located in one of the most densely populated counties in Florida. The area
was chosen in 1975 for construction of a solid waste management facility when
the surrounding land was vacant. The surrounding land was zoned in the county’s
comprehensive plan for light industrial and commercial use only. Construction of
a WTE plant began in 1980. During this time, construction of a residential
community directly west of active landfill was approved. The effect of the
landfill on residential property values was analyzed.
Houses at a particular distance from the edge of the landfill active
cell were selected and the 10-year percentage change in the house price was
obtained from a public Web site, www.zillow.com.An average value
of 10-year percentage change of house prices was obtained for all the houses at
a given distance from the edge of the active landfill cell, and this procedure
was repeated for various distances from the landfill.
Similar analysis was done for three additional Florida landfills
having residential development nearby. It can be seen from Figure 6 that the
percentage change in house prices increased significantly 600 meters to 800
meters (2,000 feet to 2,600 feet) from the landfill cell boundaries.
Statistical analysis was done using MS Excel to examine the
significance in difference of means of percentage change in house prices at
various distances. Initially an F-test was performed to evaluate whether
variances of sample data at various distances are statistically different. For
Landfill A, house data at distances below 400 meters were combined and compared
with the combined data at distances above 800 meters. The initial
F-test-obtained p-value was significantly greater than 0.05. Hence, it can be
concluded that the variances of the two samples are statistically the same at
95% confidence interval. Further, a t-test was performed assuming equal
variances, and a p-value significantly less than 0.05 was obtained. This shows
that the mean value of data below 600 meters is statistically different than the
data above 800 meters. Similar analysis for Landfills C and D showed that the
mean of the house data below 600 meters is statically different from the mean of
the house data above 800 meters. However, for Landfill E there was no
statistical difference in means at distances less than 600 meters and greater
than 800 meters.
Hence, based on this analysis, a set-back distance of 800 meters to
1,200 meters from active landfill cells is recommended to minimize the impact on
residential property values. Table 6 compares set-back distances recommended in
this study and other studies conducted on impact of landfills on housing prices.
Since the impact caused by the landfills is a function of many parameters, such
as operational characteristics and landfill age, the difference in the spatial
impact observed around the landfill is expected.
Noise Measurements—Noise
measurements at Landfill A were made in July 2006 (during typical WTE activity)
and October 2006 (during landfilling of unburned waste). Figure 7 shows the
locations of stationary meter measurements during typical WTE activity. A
stationary meter located directly in front of the WTE facility Bay 4, Location
4, captured the noise levels associated with the trucks coming and going from
the WTE facility, as well as the noise levels of backup beepers and crane
operations. This site recorded an equivalent sound level (Leq) of 64.2
dB(A), an Lmax of 76.4
dB(A), and a standard deviation of 2 dB(A). Leq is a steady-state sound having the same
A-weighted sound energy as that contained in the time-varying sound in the
measurement period, and Lmax is the
highest noise level during the measurement period. The Leq and
Lmax
values obtained at locations 1, 2, 3, and 4 (Figure 7) are shown in Table 7,
along with the standard deviation values.
A
roving meter was used to take recordings even closer to the WTE facility and on
all four sides of the operations. These sites helped determine a background
noise level associated with the landfill during WTE operation, as well as the
sound levels associated with the WTE facility directly.
A
second set of measurements was made on Landfill A in October 2006 when the WTE
facility was shut down for maintenance. During this period, all incoming waste
was sent to the landfill directly. Measurements were made directly in front of
the WTE facility Bay 4, as shown in Figure 8.
In
order to record sound levels (Table 8) associated with garbage collection
trucks, dump trucks, and transfer trucks arriving at the landfill, a microphone
setup was deployed 10 meters (25 feet) and 15 meters (50 feet) from the landfill
access road.
Noise
measurements were made on Landfill B during March and April 2007. Landfilling
was the only source of noise from this landfill. Hence, measurements were made
to capture the noise levels associated with landfilling activity.
Figure 9 shows locations of noise measurements on Landfill B.
Background measurements were taken 200 meters from the active landfill zone,
and, similar to Landfill A, measurements were made at 10 and 15 meters from the
landfill access road.
Table
10 shows a summary of noise measurements made at Landfill A and at Landfill B.
Based on field measurements at both landfills, it can be observed from Table 10
that to achieve the EPA-recommended value of 55 dB(A) for a quiet neighborhood,
a set-back distance of 1.6 km to 1.9 km should be maintained around the landfill
if no shielding occurs.
It
can be observed from Table 8 and Table 9 that Landfill A recorded higher
measurements than Landfill B. The distances recommended in Table 9 do not
account for ground effects and other topological factors that affect the sound
wave propagation between the source and the receptor. Also, it is important to
note that the noise measurements recorded may vary when there is a change in the
location of landfilling activity.
Dust Measurements—Dust
measurements were made at Landfill B over a 48-hour period. Two particulate
samplers, known as Mini Vols, were set up on Landfill B, as shown in Figure 10.
The choice of locations for the Mini Vols was somewhat limited by the
sensitivity of the equipment and the layout of the active cell.
The
first Mini Vol was located about 200 meters off the access road in an inactive
area (Figure 10). This site was upwind of the active landfill in a relatively
secluded area and provided background dust levels. The second Mini Vol was
located in the active cell area, 50 meters from where the bulldozers were moving
waste (Figure 10). This downwind location was selected to collect the
particulate matter directly associated with landfilling activity. It is
important to note that in an attempt to avoid filter clogging, the equipment was
located away from traffic that would stir up large amounts of dust. Each
location used two 24-hour filters while on location. A 38-elemental breakdown
and analysis of the dust samples was done by Chester LabNet. Table 11 gives the
net concentration (downwind-upwind) of the 10 highest elemental concentrations
coming from the landfilling activity. Increases in concentration of all major
analytes were observed.
The
Mini Vol located in the upwind location collected a total mass of 110 mg in 24
hours (14.9μg/m3) and the second
Mini Vol located in the downwind direction collected a total of 136 mg in 24
hours (18.4μg/m3). Both of these
values are below National Ambient Air Quality Standards (NAAQS) of
150μg/m3 for PM10 (US
EPA 1997).
Conclusions
and Recommendations
This
study investigated a methodology to gather scientific and quantifiable data and
recommend set-back distances from landfills to minimize nuisance impacts. Based
on the results obtained, the impact distances recommended for Landfill A are
shown in Table 12. Because of its remote location, the VOC, house prices, and
visual impact could not be evaluated for Landfill B. There, the noise impact
distance values alone would apply.
It
can be observed from Table 12 that noise is the most significant offsite impact.
Since the nuisances caused by the landfill are function of landfill
characteristics including landfill age, operating conditions, and equipment
used, the value of impact distances and the order of importance of nuisances are
expected to be site specific.
Because of the study budget, VOC concentrations were measured and the
concentrations of odorous compounds were obtained by using the default
concentration ratios of gases present in the landfill gas. Better estimation of
gaseous impacts could be done by directly measuring the concentration of various
odorous gases present in landfill gas. Also, this study did not consider the
traffic impact caused by the landfill. Traffic impact can be evaluated by
calculating the volume of traffic on the roads near the landfill and comparing
it with the standard traffic conditions. Visual impacts and bird nuisances can
be minimized by maintaining a line of tree growth around the landfill. Also,
such operational changes as active gas collection and minimizing exposed active
area, which would reduce the gas emissions from the landfill, are important to
reduce offsite impacts.