Mapping potential “drill out” scenarios in Allegheny County, Pennsylvania

SkyTruth has just launched its first Google Earth Engine app, detailing potential natural gas drilling scenarios in Allegheny County, Pennsylvania.  If you’re interested, you can view the app here.

Hydraulic fracturing — fracking — has unlocked natural gas resources from formations like the Utica Shale and Marcellus Shale, resulting in an explosion of gas-drilling activity across the Mid-Atlantic states. One of the states sitting above this hot commodity is Pennsylvania; the state boasts a massive reserve of nearly 89.5 trillion cubic feet of dry natural gas, according to the US Energy Information Administration.  In the thick of it all, Allegheny County, in the southwestern portion of the state, is one of the few counties where drilling activity has been relatively light. The county’s main defense against well drilling has been zoning regulations which require a “setback” between unconventional natural gas drilling sites and “occupied buildings.”  At present, the minimum distance required between a well pad and a building is 500 feet (unless consent has been received by the building’s owner). However, this distance may not adequately protect human health, especially in communities surrounded by drilling. Municipal officials might want to consider alternative setbacks, based on the latest scientific research on the impacts of drilling on the health of nearby residents.  This analysis evaluates a range of setback scenarios, and illustrates the likely drilling density and distribution of drilling sites across the county for each scenario.

To better understand the potential impact of drilling in Allegheny County, I analyzed several different “drill out” scenarios (Figure 1).  I developed our first Google Earth Engine app to give users a glimpse of how different setback distances and different well spacing intervals might impact the number of homes at risk from drilling impacts in the future.  Check out the analysis here.

Figure 1. A screenshot of the app when first launched.

To begin this analysis, I downloaded building footprint data for Allegheny County from the Pennsylvania Geospatial Data Clearinghouse.  Next, I downloaded shapefiles representing the centerlines of major rivers passing through the county, other hydrological features in Allegheny County, Allegheny County’s Beltway System, and county-owned roads from the Allegheny County GIS Open Data Portal.  Setback distances of 500 feet, 1,000 feet, 1,500 feet, and 2,500 feet were used to buffer the center points of “occupied buildings” in the county. I selected the minimum and maximum setback distances based upon the current Pennsylvania setback laws (500 ft.) and a recently proposed and defeated setback distance from Colorado (2,500 ft.). The latter regulation, if passed, would have been the most restrictive regulation on fracking of any state.  The 1,000 and 1,500 foot setbacks are meant to serve as intervals between these two demonstrated extremes of zoning regulation. I also created buffers around rivers and streams as well as roads. I applied a 300 foot buffer to the centerlines of all rivers and streams in the county (based upon the current regulations). I also applied a 60 foot buffer to all beltway roads and a 40 foot buffer to all county roads. These three buffer zones remained constant throughout the project.  

After applying these buffer distances to rivers, roads, and buildings, I calculated how many acres of Allegheny County were potentially open to drilling.  Using the currently required distance of 500 feet, there are approximately 57,000 acres potentially available for drilling in Allegheny County, PA (See Figure 2).  

Figure 2. Screenshot from the app showing the available drilling area in Allegheny County (shown in black) when considering the 500-foot setback from occupied structures. Current well pad locations are denoted by red dots on the map.

Using the setback distances that we identified (e.g., 500 feet, 1,000 feet, 1,500 feet, 2,500 feet), I wanted to visualize what different potential “drill out” scenarios might look like.  To do that, I had to decide how much space to leave between potential well sites. I chose to space out the potential drilling sites according to three different intervals: 40 acres per well, 80 acres per well, and 640 acres per well.  Calculating different setback distances and different spacing intervals allowed me to investigate the range of possible “drill out” in Allegheny County.  I calculated the number of new drilling sites that each “drill out” scenario could potentially support. I’ve summarized the results below:

40 acre well spacing80 acres well spacing640 acre well spacing
500 ft. setback1,00550257
1,000 ft. setback28517015
1,500 ft. setback96518
2,500 ft. setback19113

So, for example, a setback distance of 500 feet coupled with a spacing between well pads of 40 acres would allow for 1,005 new potential drilling locations.  Taking into consideration the approximate 3-5 acre area required for the development of a well pad, this suggests that 3,000-5,000 acres of land in Allegheny County could be subjected to surface well development.

For each “drill out” scenario, I mapped the number of potentially supported wells, and I put a two-mile buffer around each point to simulate the potential zone of adverse health impacts (See Figure 3).  I used the buffered points to calculate the number of “occupied structures” that would be at risk of exposure if a drilling site was built. The number of occupied structures at risk when considering each of the different scenarios is summarized in the table below:

40 acre well spacing80 acre well spacing640 acre well spacing
500 ft. setback452,751384,596210,383
1,000 ft. setback228,989217,91851,517
1,500 ft. setback95,56861,67326,897
2,500 ft. setback4,8604,6323,657
Figure 3. Screenshot from the app showing potential drill-out locations (shown in yellow), considering a 500-ft setback from occupied structures and a separation between potential drilling operations of 40 acres. Notice the area of the county potentially subjected to adverse health consequences considering a two-mile buffer zone (shown in black) around each of these locations.

Setback distances can be an important tool for municipal governments looking to reign in drilling to protect the health, safety, and quality of life of local residents.  My analysis demonstrates how setback distances can help protect the public from the adverse impacts of oil and gas drilling in Allegheny County, Pennsylvania. Please be sure to check out the app here.  

New Year, New Alerts

We just released a new version of SkyTruth Alerts, a service that notifies you about environmental incidents in areas you care about. It’s a tool we built to help us monitor environmental events in-house, and we’ve made it freely available to the public for the last six years.

We’re excited about the capabilities of the new Alerts — we wrote a blog post about it in November — and we’re looking forward to adding new features and alerts sources in the future. Here’s a quick rundown of what you need to know to get started with the new Alerts:

I used the original Alerts. Do I need to do anything to switch?

You don’t have to do a thing to continue receiving the same alert emails you’ve always received, although you’ll notice the emails have a new format. You can still view a specific alert by clicking on its link in the email.

If you want to add or change the areas of interest (AOIs) you monitor, or fine-tune the alerts you see or get emails for (a new feature), we now ask you to create an account. We only collect your email address, which we need to send you emails. We have plans to add features in the future that will also need a user account in order for them to work.

OK, so how do I register for an account in the new Alerts?

Go to SkyTruth Alerts and select Login from the burger menu. If it’s your first time here, click the Register here link to create an account.

The original Alerts worked fine! Why did SkyTruth create a new Alerts?

Web-based software has a pretty short life-span and the first Alerts system was getting harder and harder to maintain. Additionally, SkyTruth wanted to expand the number and types of alerts that we were saving as well as work on new features such as notifying subscribers when there is a change in their AOI. It became clear that the original Alerts wouldn’t be able to handle these additions.

Does the new Alerts do everything that the original Alerts did?

Almost! We’re still working on the API that a few subscribers used to integrate alerts with other software. If you spot anything else that we missed, please let us know by emailing us at

Until we have the API fixed, we’ll keep the original Alerts available at Note that this should only be used for redirecting the API and embedded links in KMZ/KML files. If your KMZ file contained a link to, you can still get it to work by pointing to

What major new features should I know about today?
  • You can filter the alerts you receive emails for.
  • You can filter the alerts shown on the map by type and date.
  • You can create AOIs that are polygon shaped.
  • You can choose a pre-defined AOI. Currently, we have states and counties ready and are working on more.
  • We’ve added or restored alerts for:
    • Oil and Gas well permits from West Virginia and Colorado
    • Florida Pollution
Can you add alerts from other websites?

Yes! Let us know what a useful source for alerts would be and we’ll consider it for the future. That email again is

SkyTruth appears on Netflix!

Last week, SkyTruth made an appearance on Netflix when their show Patriot Act with Hasan Minhaj used our interactive map of oil spills reported in the Gulf of Mexico in the years following the BP / Deepwater Horizon disaster.

To learn more about the ongoing 14-year Taylor Energy leak that was the focus of this episode, check out our chronology of spill reports and observations at the site, as well as our most recent estimate of the cumulative oil spill based on those reports.

This appearance follows a recent front page article in the Washington Post on the “oil spill you have never heard of” that also referenced reports and data generated by SkyTruth. These are two great examples of how the work we do helps raise awareness of incidents of oil pollution and other types of environmental degradation across the globe.

Big Changes Coming to SkyTruth Alerts

For the last year or so we’ve been working to revamp SkyTruth Alerts, an app we built for ourselves in 2011, and then opened up to the public a year later. The Alerts lets you see environmental incidents and notifications on a map as they are reported, and allows subscribers to sign up to receive email notifications about reported environmental incidents in areas they care about (aka “Areas of Interest” or AOIs). Technology has made a few leaps since then, so it was time for an overhaul. We’ve added some new features too. We’re excited about the changes, and we hope you will be too.  

What’s Changed?

In a lot of ways, the new SkyTruth Alerts app works the way it always has: anyone can view the map and see the latest reported alerts for a particular area. These notifications come from federal and state websites that we have “scraped” to obtain the reports. The largest source of data is the nationwide oil and hazardous materials spill reports collected by the National Response Center (i.e., NRC Reports). Anyone can sign up to receive email notifications about incidents in their AOIs.

New and Restored Sources of Alerts

As part of the Alerts revamp, we’ve restored and/or added the following sources of alerts:

  • West Virginia oil & gas drilling permits –  restored
  • Colorado oil & gas drilling permits – new
  • Florida Pollution Reports – new

Account Management

We’ve also added account management so you can update your AOIs or change your email address more easily. Signing up for an account will also let you take advantage of new tools we’ll be rolling out in the coming months (we’ll keep you posted after the launch).

New Look!

This is what SkyTruth Alerts looks like right now:

This is what you’ll see when you first open the revamped SkyTruth Alerts (subject to some possible changes over the next few weeks, as we respond to feedback and suggestions from our alpha testers):

New Features!

Here are a few of the new features we’ve added:

New Ways to Create AOIs

Right now, SkyTruth Alerts lets you create AOIs that are a square or rectangle, but that’s not always the ideal shape. In the new version, we’ve added some tools that give you a little more control: you can draw a polygon, take a “snapshot” your current map view, or select a state or county boundary from a list of pre-defined AOIs):

After you create an AOI, you can edit your AOI (or delete it and start again) before giving it a name and saving it to your My Areas list.

Filter Out the Noise

We’ve added several ways to filter what you see in Alerts, so that you can focus on what’s important to you. SkyTruth Alerts shows you the 100 most-recent incidents in your map view (double what’s shown in the current version), so filtering has the added benefit of showing you more of the types of alerts you want to see. You can filter alerts by:

Date Range

Type of Alert

Base Layers

Select from a couple of different map backdrops (“base layers”) so you can focus on what’s important to you. Below is a screenshot of SkyTruth Alerts using the “Minimal” base layer.

Alerts Within AOI Only

This can be useful if there are a lot of alerts in the surrounding area that are more recent than the alerts within your AOI.  

In the image below, there are only a few alerts are shown in the West Virginia AOI:

However, once alerts are limited to within the AOI, the picture changes:

New Ways to View Alerts Markers

In some places, there are many, many alerts in the same location. This can make it hard to move around the map because you end up clicking or tapping an alert marker when you wanted move around in the map view. It can also be hard to “grab” a particular alert marker from a stack of them.

In the first screenshot, clustering is turned on, making it easier to move around the map. Click on a cluster marker to zoom in on that area and see more alerts.

Once you’ve zeroed in on your area of interest, it can still be hard to see the forest for the trees in some locations. In the next image, clustering is turned off. You can see that there are a lot of alerts in this area, but how many exactly?

The image below shows the same area as the one above. If you click on one of the alert markers, it will “explode,” showing you all of the alerts in that location. Click on any of the exploded markers to view the report.

So when’s the Launch?

We’re getting ready to begin alpha testing in in mid-November. Lots of our current subscribers have volunteered to be testers and will be helping us put the finishing touches on the app. A big thank you to all of you who are helping us with that! Testing will last four weeks, and during that time we’ll be making continuous updates based on feedback we receive. We expect to go live with the new version by the end of the year.

A look back at 20 years of oil and gas permitting in Wyoming

A shift in priorities of the EPA under the current administration has raised awareness of an increase in oil and gas permitting across the USA. However, the increase began before the current administration. Although the federal government controls most regulations and laws that affect permitting, other factors such as global oil and gas prices, advances in drilling and production technology, and state governments’ willingness to accommodate investors have an effect on permitting and investment by energy companies. It should be pointed out that permitting does not necessarily indicate drilling as companies can request permits but then hold on to the permits until either eventually drilling, requesting a new permit, or selling the permit to another company. This can tie up land for decades and is covered in more detail by The Wilderness Society’s report: “Land Hoarders: How Stockpiling Leases is Costing Taxpayers”.

Wyoming has an economy that is built on coal and oil, but in the 80s and early 90s it was suffering from an oil glut that caused prices to drop. As prices began to recover throughout the 1990s and 2000s and eventually boom (Fig.1), some companies sought to diversify into natural gas (read more in James Hamilton’s paper “Causes and Consequences of the Oil Shock of 2007-08). Many began to drill for gas in the coal fields of Wyoming, and to apply the relatively new technology of hydraulic fracturing (“fracking”) to extract natural gas from previously uneconomic, low-permeability sandstone and shale reservoirs found throughout the Rocky Mountain West.

Oil and gas prices since 1985.

Figure 1. Oil and gas prices since 1985.

The oil and gas boom ended abruptly in 2008 when the effect of the global financial crisis reached the oil and gas markets and prices plummeted.

To better understand the effect these events had on Wyoming, I analyzed permits for new oil and gas wells, issued by the state over the past 20 years. This data is freely available from the Wyoming Oil and Gas Conservation Commision website: First, I should point out that this data has inconsistencies and holes, due to apparent data entry errors like missing or incorrect dates, missing latitude or longitude, typos, etc. Unfortunately, this meant nearly 24% of the total permits had to be left out of my analysis. Some errors still remain, as seen in this map of permit applications received by the state (Fig. 2). Each county is colored differently and there appear to be some permits which either have the wrong county listed or incorrect map coordinates.

Distribution of oil and gas drilling permit applications, color coded by county.

Figure 2. Distribution of oil and gas drilling permit applications, color coded by county.

What immediately stands out is the relatively densely-packed permits in Campbell county, in the north-east of the state. When I looked closer at this county over time, I saw that most of the permit applications were submitted during the beginning of the boom of 1998-2008. This is quickly followed by a sharp drop around 2000, the time hydraulic fracking made drilling in other parts of the state (and country) more profitable. The original method of coal bed methane drilling was considered uneconomical compared to this new fracking method. At that time, I saw a rise in permit applications across other counties (Fig. 3), but far more subdued than the earlier rush, possibly because fracking made deposits across the country viable and so the increase was more widespread across and outside Wyoming. This is just a theory though, these could easily be due to business strategies of companies “capturing” land before their competitors.

Applications for oil and gas drilling permits received over time by county.

Figure 3. Applications for oil and gas drilling permits received over time by county.

The rate of permit applications slows for all counties as the boom ended around 2008 with a short-lived rise leading up to 2016. The boom and bust periods can be seen more clearly when I looked at the overall quantity of permit applications across Wyoming (Fig. 4).

Total number of oil and gas drilling permits applied for in Wyoming.

Figure 4. Total number of oil and gas drilling permits applied for in Wyoming.

The initial rush of the boom was followed by a dip and second climb as fracking technology took off. This is followed by the bust of 2008. There is a slight rise again around 2016, but it drops off by 2017. The effect of this activity is closely reflected in unemployment figures for the state (Fig. 5). Considering that I am looking at permitting however, and not drilling, this correlation should be seen as a reflection of oil and gas companies’ business activities in a holistic sense.

Unemployment rate for Wyoming over the past 20 years.

Figure 5. Unemployment rate for Wyoming over the past 20 years.

Initially, there’s an overall steady decline in unemployment as the boom sweeps up employees but this rockets up once the bust comes along. Interestingly, between 2012 and 2016, there is a steady rise in permit applications which is reflected by the steady drop in unemployment but this is interrupted by a bump in unemployment around 2016. The restoring of the unemployment level after 2016 is not reflected in the drop in permit applications, however. Those appear to drop off.

Although there are booms and busts, the overall number of well permits is constantly increasing (by simple fact of the number of new permits applied for always outweighing the number of permits expiring). The animated image below (Img. 1) shows the growth of oil and gas permit applications as companies move across the state.

Image 1. Permits applied for over the past 20 years.

Image 1. Permits applied for over the past 20 years. (Click to see time-series)

Graphs and maps give us a good idea of the trends but sometimes it is even more helpful to see the physical reality of these numbers.  This is an area in the most heavily permitted county, Campbell (Img. 2).

Image 2. Comparison of an area of Campbell county from July 1999 to July 2018.

As well as the dramatic increase in well pads (i.e., drilling sites), these images show the addition of access roads threading across the landscape.

What this data doesn’t show is the large amount of orphaned wells that were left behind after the price of oil and natural gas dropped in 2008. This has left a legacy of about 3600 abandoned wells (scroll to bottom for total number of orphaned wells currently tracked by Wyoming Oil and Gas Conservation Commision). Often the state, and therefore, the taxpayers, are left to handle this burden because the responsible companies are either unknown, unable to cover the cleanup costs, or have declared bankruptcy and disappeared. Understandably, the state would prefer to see the wells operate once more rather than paying considerable amounts of money to seal them up and restore the land. But these aging, unsecured wells pose a threat to the environment and to public health.  

Many of the coalbed methane wells built at the beginning of the boom were approved with permission to dump untreated “flowback water” on the surface. The companies convinced the state that this  fluid, coming straight from the coal seams targeted by the drilling, would be beneficial for the parched land even though most of the untreated fluid was highly saline. Also, the effect of flooding the land with large volumes of water was extremely unnatural to the existing ecosystem. Many areas that were normally good for grazing became unusable because they were flooded with this salty water. Land that was adapted to little rainfall and snowmelt was suddenly exposed to a constant flow of brine. The companies pushed the idea of plentiful of water for agriculture and wildlife to drink while downplaying the issue of the quality of the water. The state also towed this line while court battles challenging the “beneficial use” permits, led by landowners and conservation groups, were upheld in court. Eventually, they implemented a water-to-gas ratio cap on surface discharges since many of the wells were producing plenty of salty water but little or even no gas at all.

One other trend that I discovered while scrutinizing the permit database was the time it took to process these permits (Fig. 6 & 7). Plotting permit approval times at first appears to show a distribution that follows the general trends that I’ve seen so far, tracking the boom and bust periods. For comparison, I plotted these for both the year of permit application (Fig. 6) and year of approval (Fig. 7).

Figure 6. Permit approval time arranged by year of application.

Figure 6. Permit approval time arranged by year of application.


Figure 7. Permit approval time arranged by year of approval.

Figure 7. Permit approval time arranged by year of approval.

The red lines track the annual average wait time and give a clearer picture of the trend. The spread of wait times fluctuate far more than the actual average wait time. Although the average does not appear to fluctuate much, the scale is a little deceptive as the average wait time extends from 15 days in 1998 to 40 days in the year 2000. The average wait time appears to initially rise with the start of each drilling boom but even out fairly quickly. This changes later when the average wait time climbs sharply around 2013. By 2017, the average wait time has increased considerably to 130 days.

These trends offer insight into the recent history of oil and gas permitting activity in Wyoming. It should be noted that although there was a lot of ‘noise’ in the data that I had to correct or discard, the remaining data helps give me a clearer sense of how oil and gas development is driving change on Wyoming’s landscape. My analysis has been based purely on the history of permitting in Wyoming, not actual drilling. For an analysis on drilling, please look at the Fracktracker Alliance’s page on oil and gas activity in Wyoming. I hope you’ve enjoyed this breakdown of permit data for Wyoming. I hope to take a similar look at other states’ drilling permits, so stay tuned!