Systems and methods for fenceline air monitoring of airborne hazardous materials

The invention provides systems for perimeter air quality monitoring that can establish background levels of target contaminants in ambient air prior to initiation of remedial activities. The systems can develop remedial action levels that are protective of the public health for dust and vapors at the remediation property, and can monitor and document fence line ambient air levels of target contaminants during remedial activities. Accordingly the systems and process allow for evaluation of the need for dust or vapor control measures to reduce airborne containment levels to below levels of concern.

FIELD OF THE INVENTION 
The invention relates to systems and methods for monitoring airborne 
hazardous materials, and more particularly to systems and methods for 
reducing hazardous conditions at environmental remediation sites. 
BACKGROUND OF THE INVENTION 
The remediation of soil contaminated by hazardous materials is an important 
environmental goal. In particular, remediation of contaminated sites 
removes from the local community a source of hazardous waste, and reclaims 
that land for a beneficial use. Consequently, the process of remediation 
is an important and valuable tool for land management, and its use has 
grown substantially in the United States. 
However, as beneficial as remediation is, the process itself has some 
inherent risks. In particular, hazardous materials are present at the 
remediation site, which, although dangerous in themselves, are often in a 
stable form and if left untouched present a low risk to the surrounding 
community. Remediation often requires the removal of the contaminated 
materials from the remediation site causing subsurface soils to be 
disturbed. These subsurface soils may contain any number of hazardous 
materials that are easily made airborne, including volatile and 
semi-volatile organic compounds (VOC and SVOC), such as benzene and 
polycyclic aromatic hydrocarbons (PAH). The release of VOCs and SVOCs from 
remediation sites provides a risk of toxicity to the surrounding 
community, and the disturbance of soil containing these materials can 
cause ambient air quality to degrade substantially. Once released to the 
ambient air, these compounds are free to move away from the remediation 
site and into the local community based on prevailing meteorological 
conditions. 
Although systems exist today for measuring air quality, these systems are 
generally just stand alone air sampling devices that typically are only 
employed once an air quality problem is suspected. Accordingly, these 
systems are generally reactionary, only providing information regarding 
the damage done. 
Accordingly, it would be desirable to have a real time system for 
monitoring the quality of air leaving a remediation site to prevent or 
reduce public health risks to surrounding communities associated with 
on-site activities. 
SUMMARY OF THE INVENTION 
The invention provides systems for perimeter air quality monitoring that 
can establish background levels of target contaminants in ambient air 
prior to initiation of remedial activities. The systems can develop 
remedial action levels that are protective of the public health for dust 
and vapors at the remediation property, and can monitor and document fence 
line ambient air levels of target contaminants during remedial activities. 
Accordingly the systems and process allow for evaluation of the need for 
dust or vapor control measures to reduce airborne containment levels to 
below levels of concern. 
To this end, the systems and methods described herein can include apparatus 
for monitoring airborne hazardous materials that includes a gas detector 
for analyzing an air sample to detect volatile organic compounds and a 
dust detector for detecting airborne particulate matter. The systems can 
also include a data communications device that couples to the gas detector 
and to the dust detector and that is capable of transmitting data signals 
over a data network. The apparatus can also include a gas processing 
instrument that is capable of identifying the types of volatile organic 
compound present in an air sample. The systems can further comprise an 
alarm that will generate an external notification signal which is 
representative of a volatile organic compound being at a concentration 
above a designated concentration level. Similarly, the systems described 
herein can also include an alarm for generating an external notification 
signal when dust levels have been detected above a concentration level 
that is acceptable to public health. 
In one embodiment, the systems are programable such that an operator can 
select the individual volatile organic compounds that are being 
identified, monitored, or detected by the systems described herein. In a 
further embodiment, the systems can include controllers that are coupled 
to data communication devices and that allow for the access and control of 
the monitoring systems from a remote location. 
The systems described herein can further comprise mechanisms for 
designating a threshold concentration of a selected volatile organic 
compound which is representative of a protective human health risk based 
concentration. Similarly, the systems include mechanisms for designating a 
threshold concentration of a dust material which is representative of a 
human health risk based concentration. The systems described herein can 
include weather-tight housings for enclosing the elements of the system 
and for providing an interior chamber that has a controlled interior 
environment. 
In a further embodiment, the invention provides systems for monitoring 
airborne hazardous material that include a plurality of air monitoring 
stations that can be located around the perimeter of a remediation site. 
Each of the air monitoring stations can include a gas detector for 
analyzing an air sample to detect volatile organic compounds, a dust 
detector for detecting airborne particulate matter, and a data 
communications device coupled to the gas detector and to the dust detector 
and being capable of transmitting data signals over a data network. These 
systems can further include a data processor which is in communication 
with each of the data communication devices of the plural monitoring 
stations. The data processor can act and operate to control and monitor 
the stations and to compare the information received from these monitoring 
stations. The apparatus can also include a detector for generating a 
signal that is representative of wind direction across the site being 
monitored. These systems can also include a site contribution processor 
that is coupled to the detector, a gas detector and a dust detector for 
generating a signal representative of airborne hazardous materials 
generated at the site being monitored. 
These systems can also include an alarm for generating a warning signal 
representative of a warning to begin vapor and or dust suppression 
controls to reduce airborne hazardous materials levels. 
In another aspect, the invention can be understood as processes for 
monitoring airborne concentrations of volatile compounds and dust around a 
site. These processes can comprise the acts of providing a plurality of 
monitoring stations, each having a gas detector, a dust detector and a 
data communications device and a data processor, locating the monitoring 
stations around the perimeter of the site being remediated, sampling 
concentrations of volatile organic compounds and dust at each monitoring 
station, communicating the sampling information through the data 
communication device to the data processor and operating the data 
processor to compare sampling information to acceptable concentrations of 
total volatile organic compounds, individual volatile organic compounds 
and dust. These processes can also include the step of providing a 
detector for determining wind direction at the site being monitored and 
determining an upwind monitoring station and a downwind monitoring 
station, and processing sample information from the upwind monitoring and 
sampling information from the downwind monitoring station to determine a 
concentration of airborne particulate matter contributed from the site. 
Other objects of the invention will, in part, be obvious, and, in part, be 
shown from the following description of the systems and methods shown 
herein.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
To provide an overall understanding of the invention, certain illustrative 
embodiments will now be described, including a system for monitoring air 
quality at a remediation site. However, it will be understood by one of 
ordinary skill in the art that the systems and processes described herein 
can be adapted and modified to provide systems that can be employed to 
monitor air quality, water quality, or soil quality, or for any other 
suitable application as well as to provide systems for use at any type of 
site in need of monitoring. Other additions and modifications can be made 
to the invention without departing from the scope hereof. 
FIG. 1 depicts one air monitoring station 10 that provides for monitoring 
airborne hazardous material. The air monitoring station 10 depicted in 
FIG. 1 includes a cabinet 12 mounted to a base 14. The cabinet 12 depicted 
in FIG. 1 is approximately three feet high by four feet wide and one foot 
deep. The cabinet 12 stands on a base formed from an iron pipe fixture 
that is connected to a cement base 16. The air monitoring station 10 is 
approximately seven to eight feet tall. The cabinets 12 and base 14 are 
adapted to withstand exposure to normal and severe weather conditions, 
allowing the air monitoring station 10 to be maintained outdoors for a 
prolonged period of time. Accordingly, the air monitoring station 10 can 
act as a permanent, or near permanent, sentry for monitoring for airborne 
hazardous material and can be part of a containment system capable of 
sounding an alarm upon the detection of airborne hazardous materials 
representative of a public health risk. To that end, the air monitoring 
station can provide for sounding a siren that instructs a remediation crew 
to take preventive measures to contain or curtail the production of 
airborne hazardous materials. Moreover, the air monitoring system 10 can 
be employed as part of a system for generating a database of air sample 
data to maintain a record of air quality during remediation activities. 
FIG. 2 depicts the components of the air monitoring station 10 that are 
maintained within the housing 12. Specifically, FIG. 2 depicts that the 
housing 12 contains a dust detector 20, a gas analyzer 22, a data 
communication device 24, and a reservoir of carrier gas 28. FIG. 2 further 
depicts that the housing 12 has mounted thereto a gas sampling inlet 30, a 
dust sampling inlet 32, and an antenna 34. Maintained within the housing 
12, for controlling the environment therein, are heat exchanger elements 
38, and a heater element 39. As shown in FIG. 2, the depicted housing 12 
has a heat exchanger 38 mounted on either side of the housing 12. The 
housing 12 depicted in FIG. 1 is a weather-tight housing, and preferably 
is a NEMA-4 type housing suitable for providing a weathertight housing 
resistance to the elements and capable of protecting the components of the 
air monitoring station 10 from exposure to the external environment. As 
can be seen from FIG. 2, the housing 12 contains those heating and air 
conditioning devices necessary to maintain the interior compartment of 
housing 12 at selected environmental conditions. This is understood to 
provide the instrumentation, such as the gas analyzer 22, with a 
controlled operatiang environment, thereby reducing the likelihood that 
environmental conditions will influence the operation of the 
instrumentation. To this end, as will be understood from the description 
below, the environmental control devices, such as the heat exchanger gas, 
can be monitored and controlled from a central station, thereby allowing 
repair or adjustment if necessary. It will be understood that the depicted 
devices are provided for illustrative purposes, and that other devices and 
arrangements of devices can be employed without departing from the scope 
of the invention. 
FIG. 2 further depicts that the housing 12 includes a dust detector element 
20. The dust detector 20 monitors respirable dust levels as a surrogate 
for monitoring SVOCs such as PAHs. As is known in the art, surrogate 
monitoring provides a technique for estimating the concentration level of 
certain chemicals by examining the concentration level of a measurable 
surrogate and estimating, such as from soil samples, the percentage of 
that surrogate that is composed of the chemical being monitored. Although 
the systems described herein employ dust as a surrogate for PAH levels, 
any other surrogate detection method can be employed, with the selected 
method typically being chosen for being the optimal technique for the 
material being detected or for the given site conditions. The dust 
detector element 20 can be a light scattering particulate matter detector, 
and more particularly can be an infrared electromagnetic particle 
detector. One such infrared particle detector is manufactured and sold by 
the MIE Company of Billerica, Mass. As further shown by FIG. 2, the 
particle detector 20 couples by tubular elements 40 to the air sampling 
tube 32. The air sampling tube 32 extends out of the housing 12 and is 
capable of collecting an air sample that can be carried through tube 40 to 
the dust detector 20. The dust detector 20 can then operate as normal on 
the collected air sample to determine the concentration level of 
particulate matter in the air around the air monitoring station 10. The 
concentration level of particulate matter can be employed to estimate the 
concentration level of PAHs, or other chemical, in the air sample. 
FIG. 2 further depicts that the housing 12 can contain a gas detector for 
analyzing an air sample to detect volatile organic compounds. In the 
embodiment depicted in FIG. 2 the gas detector 22 includes a gas 
chromatograph of the type manufactured and sold by PE Photovac of Norwalk, 
Conn. The gas chromatograph 22 couples via tubing 42 to the air sampling 
tube 30 that extends outwardly from the housing 12. The dust sampling 
inlet 30 can collect air samples from the ambient environment and provide 
the air samples through tube 42 to the gas chromatograph 22. There the gas 
chromatograph 22 can operate as normal to determine the concentration of 
volatile organic compounds in the environment ambient to the air 
monitoring station 10. 
FIG. 2 further depicts that the housing 12 contains a data communications 
device 24. In the depicted embodiment the data communications device 24 is 
a radio of the type manufactured by the Motorola Company of Austin, Texas. 
The radio 24 couples to the antenna 34 for broadcasting via a radio link 
information signals to a central processing station (not shown) that can 
be employed for monitoring the sampling data generated at the air 
monitoring station 10. To this end, both the gas detector 22 and the dust 
detector 20 can couple to the data communication device 24 to provide the 
data communication device 24 with air sampling information. The data 
communication device 22 can format the air sampling data into a format 
suitable for transmission via a data network and broadcast this data to 
the data network for further analysis and recording by the central data 
processing system. Although the data communication device 24 depicted in 
FIG. 2 is a radio frequency link device, it will be apparent to one of 
ordinary skill in the art that other communication devices are practicable 
with the present invention, including cable networks, infrared links, 
short haul modem link or any other type of communication links suitable 
for carrying data from a remote location to a central processing location. 
A reservoir of carrier gas 28 is also maintained within the housing 12 and 
acts to provide a source of carrying gas for delivering a sample into the 
gas chromatograph. In one embodiment, the reservoir contains helium, 
although any other suitable gas or combination of gases can be employed. 
The carrier gas can be an ultra zero air gas which gives the gas 
chromatograph a carrier gas to allow air to move through the columns of 
the gas chromatograph. 
In operation, the individual components of the air monitoring station 10 
can operate to collect samples of air at the site of the air monitoring 
station 10 and to process those samples to determine the concentration 
levels of airborne hazardous material in the environment around the air 
monitoring station. More particularly, the gas detector 22 can, through 
the air sampling tube 30, collect an air sample and process the air sample 
to determine the concentration of volatile organic compounds in the air or 
around the air monitoring station. The gas detector 22 can be a 
programmable device that will allow a user to set a concentration level of 
VOCs that indicates a public health risk has been triggered. The dust 
detector 20 can continuously sample the air around the monitoring station 
10 to estimate the concentration of SVOCs or other materials in the air. 
Data from both detectors 20 and 22 will be passed, through the data 
communications device 24 to the central processor to provide continuous 
real-time air quality data for the air around the monitoring station 10. 
In cooperation with the air monitoring stations, the systems described 
herein can also include a weather monitoring station, such as the weather 
monitoring station depicted in FIG. 3. The weather monitoring station can 
collect information regarding atmospheric conditions including wind 
direction, wind speed, humidity, and any other meteorological condition 
relevant to an analysis of concentration levels of airborne materials. 
FIG. 3 depicts more specifically a weather station 50 that includes a 
weather processor unit 52, a data communication device 54, a solar cell 
panel 58, a wind speed meter 60, a vane 62, an antenna 64, and the base 
68. The weather station 50 is designed to be maintained outdoors and 
therefore the electrical components are maintained within weathertight 
housings. The weather station 50 depicted in FIG. 3 is approximately 14 
feet high and is assembled from components that are commercially 
available. 
In particular, the wind speed meter 60, and weather vane 62 can be any 
commercially available components suitable for measuring wind speed and 
wind direction. The weather processor 52 depicted in FIG. 3 can be any 
suitable meteorological data such as the type sold by Campbell Scientific, 
Inc., under the name of MET DataOne. The data communication device 54 can 
be a radio frequency communication device, such as the data communication 
device 24 employed by the air monitoring system 10. 
The components of the weather station 50 are interconnected such that the 
processor 52 can receive power from the solar cell panel 58. The processor 
52 is a data processing unit that connects with the various measuring 
elements such as the vane 62 and wind speed meter 60. Other elements such 
as a barometer, humidity detector, or any other suitable meteorological 
measuring device can also be interconnected to the processor 52. The 
processor 52 collects the information and creates a data package that can 
include information representative of the time at which the data was 
collected. This information can be transferred via an electrical 
communication link to the data communication device 54. The data 
communication device 54 then can connect to the data network which can 
transmit data to the central data processing unit. In this way, 
information representative of the meteorological conditions at the 
remediation site can be maintained and detected by the central data 
processing unit. 
The weather station 50 and the air monitoring station 10 can cooperate to 
provide fence line monitoring of air quality at a remediation site. For 
example, in one practice a plurality of air monitoring stations 10 are 
located around the perimeter of a remediation site, such as at locations 
that correspond to major compass headings. The weather station 50 can be 
centrally located at the site, or placed at the location most suited for 
measuring site weather conditions. Optionally, several weather stations 
can be employed. The air monitoring stations and weather station provide a 
continuous stream of real-time air quality data and environmental 
conditions to a control data processor. The control data processor can 
employ this information for monitoring air quality along the full 
perimeter of the remediation site. 
FIG. 4 depicts a graphical representation of one such system for monitoring 
the air quality about the full perimeter of a remediation site. 
Specifically, FIG. 4 is a screen shot of a computer program operating on 
the central processing unit that monitors the air monitoring stations and 
weather station described above. FIG. 4 shows that a plurality of air 
monitoring stations are placed around the perimeter of the remediation 
site. It should be apparent that in other embodiments of the invention, 
the system can employ more or less air monitoring stations as well as more 
or less weather monitoring stations. Furthermore, in other embodiments of 
the invention, air monitoring stations can be placed at locations other 
than at the perimeter, including at locations that are remote from the 
remediation site but, perhaps are sites of acute interest, such as a local 
elementary school, a daycare center or a hospital. 
An operator at the central processing unit can monitor each of the air 
monitoring stations and the weather station to see the status of the air 
quality at that particular location. To this end, the display provides to 
the operator a functional block representation of each of the air 
monitoring stations at the site, wherein the functional block contains 
information such as the mode of operation, the concentration level of the 
VOCs measured by that station, and the concentration level of dust 
measured at that station. Similarly, a functional block is provided to 
represent the weather station 50. The weather station functional block 
provides information representative of the wind direction, wind speed, the 
ambient air temperature and the relative humidity. All the information 
displayed by the central processor to the operator can be stored in a 
database to maintain a real-time record of the air quality and weather 
conditions at the perimeter of the remediation site. This database of 
information can be reviewed at a later date to demonstrate that 
unacceptable levels of hazardous materials did not pass over the perimeter 
of a remediation site and into the local community. 
The display depicted in FIG. 4 further includes an alarm status block that 
indicates the relative alarm levels under which any remediation activity 
is partaking. The alarm status information includes a level one, level two 
and level three indicator. The level one indicator designates an "all 
clear" statement representative of the fact that the system detects no 
unacceptable risk to public health created by activity at the remediation 
site. A level two indicator represents a "caution" signal that indicates 
remediation activity may be rising to a level of concern for the public 
health. A level three indicator represents an "alert" signal that 
represents the detection of unhealthful concentrations of hazardous 
materials passing over the perimeter of the remediation site. A level 
three alarm warning can cause the central processor to sound a siren, or 
other type of physical alarm, or external notification that is broadcast 
to workers at the site. This alarm signal directs the workers at the site 
to take containment steps in order to reduce the flow of hazardous 
material past the perimeter of the remediation site. These steps can 
include: stopping all work, including excavating; laying down a protective 
foam over all newly exposed subsurfaces; or any other suitable containment 
step. Optionally, the external notification can be transmitted local 
community to officials. 
The alarm status indicated in FIG. 4 arises from any of the air monitoring 
stations indicating an unacceptably high level of concentration of 
hazardous material passing the perimeter of the remediation site. To 
determine more accurately the cause of the alarm, an operator at the 
central processing site can direct the central processing unit to display 
information representative of air monitoring conditions at each of the 
specific sites. FIG. 5 depicts a screen shot representing a display that 
shows the air sample data collected at one particular site. Specifically 
FIG. 5 shows an alarm status specific to the particular station, in this 
case station one. FIG. 5 further depicts that the gas detector, in this 
case a gas chromatograph. As shown in FIG. 5, the gas chromatograph can 
report in the mode in which the gas chromatograph is operating. In this 
embodiment, the mode is set as "VOC" reprenting a mode of operation in 
which volatile organic compounds are being detected. The gas 
chromatorgraph status also includes a report of the total VOC 
concentration. If the total VOC concentration is above an acceptable level 
of VOCs, the gas chromatograph can switch into an analyze and identify 
mode in which the air sample is analyzed to determine to the receive 
concentrations of certain selected compounds. FIG. 5 depicts one 
embodiment wherein the GC analyzes the air sample to determine the 
concentration of benzene, toluene as well as other particular VOCs that 
are of interest at that remediation site. The gas chromatograph also 
reports internal status regarding the instruments' operations. This could 
include information regarding the gas pressure and column temperature as 
well as the battery voltage. The gas chromatograph also reports 
information that identifies the run under which the results are performed. 
This can include a run number, a time at which the run was performed and 
the date on which the run is performed. FIG. 5 also depicts that each 
individual station can report information regarding the internal 
environment of the air monitoring station. This internal environment 
information can include the temperature, the operational status of the 
heat exchangers, and whether the door is open or closed on the air 
monitoring station. FIG. 5 further depicts that the dust meter can report 
information regarding the relative concentration of dust in the air at the 
site of the air monitoring station. Finally, the air monitoring station 
can include a graphic that shows the relative concentrations of the dust 
and the VOCs being detected over time by the air monitoring station. 
FIG. 5 also shows that the air monitoring station indicates the wind 
direction at the monitoring station. By monitoring wind direction, the 
central processor can tell whether or not the air monitoring station 
reporting unacceptably high concentration levels is upwind or downwind of 
the remediation site. This allows the central processing station to 
determine in which direction airborne hazardous materials are traveling. 
Moreover, this also allows the central processing unit to determine 
whether or not the unacceptably high levels of airborne hazardous 
materials arises from activities at the remediation site. Specifically, 
the central processing system can select an upwind monitoring station and 
a downwind monitoring station. The relative concentrations of particulate 
matter between the upwind station and the downwind station can be 
compared. In this way, it can be determined whether or not air quality has 
been affected by activity at the remediation site, or whether or not air 
being carried into the remediation site is already sufficiently 
contaminated to be deemed unhealthful. In one step, the relative 
concentration level of VOCs from the upwind location is compared to the 
relative concentration level of VOCs at the downward concentration level, 
particularly by subtracting the two numbers. The difference between the 
two concentration levels is understood as the site contribution to VOCs in 
the environment. Based on this differential information, the remediation 
site can determine whether or not containment activities at the 
remediation site could be effective in improving air quality downwind of 
the remediation site. 
The above described embodiments are merely illustrative of the systems and 
methods ofthe invention, and other systems and methods, such as systems 
for monitoring air quality at a chemical plant or for monitoring air 
quality moving into an enclosed area. Accordingly, it will be understood 
that the invention is not to be limited to the embodiments disclosed 
herein, but is to be understood from the following claims, which are to be 
interpreted as broadly as allowed under the law.