Siting projects use the full spectrum of GIS data, including vector date, raster data, attribute data, and imagery. As you learned in Lesson 3, vector data is represented by points, lines, or polygons, while raster data can consist of gridded data, such as topographical maps and digital elevation models, attribute data, which describes characteristics of the spatial features, and, finally, aerial and satellite imagery.

Where to find GIS information

There are many sources for obtaining data for siting projects. Many sources of data are available for download, and I would encourage you to explore on your own to find additional sources. A good summary of the topic of GIS data sources can be found at Maps & Geospatial: Geographic Information Systems (GIS) .

The USGS Center for Excellence for Geospatial Information Sciences is a good place to start finding data on the national level. This is a gateway to the National Map, a collaborative effort among the USGS and other federal, state, and local partners to improve and deliver topographic information for the Nation. Raw GIS data can also be accessed and downloaded from the USGS National Atlas Raw Data Download site. Another good starting point for nationwide data is data.gov: geospatial. This is the federal government's "one-stop shop" for finding and using geographic data. The data categories important to siting projects that you can browse and download include:

• Environment
• Political Boundaries
• Agriculture
• Atmosphere
• Biology
• Demographic
• Elevation
• Geology
• Imagery and Basemaps
• Inland waters
• Transportation
• Utilities

Figure 8.1: Here is an example of how soils data is displayed and used. In this application, soils data was combined with landuse data to determine runoff coefficients for use in estimating runoff to streams during rainfall events.

Credit: Ron Santini

Why we need it

Soils information plays an important role in both the engineering and the environmental aspects of siting. From an engineering perspective, soils data provides information about soil stability, depth to groundwater, depth to bedrock, and other characteristics that impact the construction of transmission towers. From an environmental perspective, soils information provides information about runoff and erosion potential, wetlands, and groundwater.

Where to find it

• The Natural Resources Conservation Service at the United States Department of Agriculture maintains soils surveys for most every county in the United States. In addition, the local county agriculture extension office also has this information available in both digital and hard copy form.
• State and local soils data can be searched and downloaded from the U.S. Department of Agriculture Geospatial Data Gateway. Click on the big green GET DATA button at the top center of the page. You will be directed to the soil data mart to select a state you are interested in.

Figure 8.2: Topographic map of Bellefonte, PA

Credit: Penn State University

Topographic maps provide much more information than just showing the physical characteristics of the land. In this section of a USGS Topo Quad, not only are the land contours visible, but this map also shows the major roads leading into and out of Bellefonte, PA, the Bellefonte street system, the major structures present, individual residences, railroad tracks, power lines, and much more. Topo maps play a major part in siting electric transmission lines.

Why we need it

Topographic data shows the lay of the land, and topography is a critical criterion in the selection of a proposed route or alternate routes. By reviewing topographical data, siting planners and engineers can identify slope and stability issues, wetlands, stream crossings, etc., to select the most cost-effective route while minimizing impacts to the environment. This data also allows engineers to develop plans to mitigate the environmental impact during the construction phase. For example, in the United States, each stream crossing for temporary roads requires obtaining a state permit. In addition, erosion and sedimentation control plans are required for construction activities that will impact streams.

Where to find it

• Topographical maps are available for the most of the United States. Individual maps can be downloaded from the USGS The National Map US Topo site. On the left side menu, click on "Download Maps (Map Store)" to navigate to the interactive map where you can locate and download topographical maps.
• Digital Elevation Model (DEM) data can also be downloaded from the National Map. Landcover data can also be downloaded from that site.

Figure 8.3: Example of a Geologic Map

Credit: National Atlas, US Geological Survey

Why we need it

Geologic data provides siting engineers with the information they need to determine earthquake and foundation design requirements for towers. Geologists and environmental scientists use the geologic data to determine what type of rock underlays the route and whether this rock has characteristics that could cause environmental concerns if exposed or disturbed.

Two examples come to mind. The first is an overhead electric transmission line constructed by a major electric utility through Panther Valley in western North Carolina. During the construction of the transmission line, acidic rock was exposed. When exposed to air and water, this rock created acidic runoff impacting otherwise pristine streams. Action by the utility company to mitigate this rock exposure prevented widespread surface water degradation. A second, and more costly, example is the construction of Interstate I-99 through Central Pennsylvania. During I-99 construction in 2003, Pennsylvania Department of Transportation (PennDOT) crews first dug into the sulfur-bearing rock material (pyrite) in the Skytop section, near State College, and then continued to dig, using some of the million cubic yards of pyrite-laced sandstone as fill under the new highway and leaving the rest in spoil piles along the road. Seven years later, in 2010, after I-99 excavation exposed a massive amount of sulfur-bearing rocks, officials said the cost to undo the environmental damage totaled $100 million! Here is just one link to the I-99 problem: NY Times article

Figure 8.4: I-99 Acid Rock Remediation

Credit: Mining Waste Treatment Technology Selection

Where to find it

• The National Geologic Map Database is a USGS maintained catalog of geologic and geoscience maps and data.
• Additional sources of digital geologic data can be obtained from many individual State Geological Survey websites. Here is an example from the Maryland Geological Survey.

Figure 8.5: Aquia Harbour - Garrisonville 230kV Double-Circuit Line

Credit: Dominion Resources

This aerial photo shows how Dominion Resources use aerial photography to overlay proposed transmission lines. It provides the transmission line siting team with a visual picture of where to position transmission lines to minimize the impact on people and the environment. There are times when the optimum route does have an impact, such as the corridor route depicted in the above aerial.

Figure 8.6: Aerial view of the University Park campus of Penn State

Credit: Andy Colwell

Why we need it

Aerial and satellite imagery give us a picture in time of what the landscape of the project areas looks like. This imagery provides much more detail than a topographical map. By overlaying planned routes on aerial images, siting planners can readily visualize obstacles that can hinder permitting and construction. For example, population density, structure density, wetlands, water bodies, forest land, agriculture operations, and existing transmission lines are easily identified through an analysis of the aerial imagery. In addition, by comparing current and historical imagery, siting planners can identify projected commercial and residential growth areas and plan alternate routes to circumvent them.

Where to find it

• The United States Department of Agriculture maintains the National Agriculture Imagery Program (NAIP). NAIP acquires aerial imagery during the agricultural growing seasons in the continental United States. A primary goal of the NAIP program is to make digital orthophotography available to governmental agencies and the public within a year of acquisition.
• Another source for aerial imagery is the USGS National Aerial Imagery Program.
• Most state and county governments make imagery available for use in GIS applications. For example, 2005 Illinois Digital Orthophoto Quarter Quadrangle data can be downloaded from the Illinois State Library. See "Individual State GIS Data" later in this lesson for a comprehensive list of available state GIS data.

Figure 8.7: Power and environment can exist side-by-side. These BPA transmission towers are located in a wetland and wildlife refuge below McNary Dam in eastern Oregon. The refuge is part of the Columbia River dam project, built by the U.S. Army Corps of Engineers. BPA's power towers were designed to be compatible with the wetlands and refuge set aside in the area.

Credit: Bonneville Power Administration

Why we need it

The impact on water quality from siting corridors is a major concern during construction, and identifying streams and wetlands to be crossed or encroached on during construction is a an important factor in siting decisions. The location of wild and scenic rivers, special stream designations, such as cold water fisheries or trout streams, or impaired streams may require additional permitting during the planning phase of siting and increased monitoring during and after the construction phase. The location of waters used as sources for public drinking water may require additional erosion and sedimentation control permitting and monitoring. The construction of power lines through wetlands or constructing road crossings through wetlands requires a wetlands identification and assessment, and a permit issued by the US Army Corps of Engineers. The permit will outline the mitigation steps to minimize the impact to the wetland.

Where to find it

• The National Hydrography Dataset (NHD) is the surface water component of The National Map. The NHD is a digital vector dataset used by geographic information systems (GIS). It contains features such as lakes, ponds, streams, rivers, canals, dams, and stream gauges. These data are designed to be used in general mapping and in the analysis of surface-water systems.
• The United States Environmental Protection Agency (USEPA) US waters. Watershed Assessment, Tracking & Environmental ResultS (WATERS) is an integrated information system for the nation's surface waters. The EPA Office of Water manages numerous programs in support of the Agency's water quality efforts. Many of these programs collect and store water quality related data in databases.
• USEPA's Surf Your Watershed provides data about individual watersheds and links to the USEPA's Envirofacts Warehouse where additional data for water, waste, air, land, toxins, compliance, radiation, and other data can be accessed and downloaded.
• The United States Geological Survey collects water resources data from approximately 1.5 million sites throughout the United States, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands. Real-time information about surface water, groundwater, and water quality can be accessed and retrieved through the National Water Information System.
• National Oceanic and Atmospheric Administration's Hydrometeorological Design Studies Center contains precipitation data, links to watershed and stream-flow data, and maps and aerial photographs.
• The CUAHSI Hydrologic Information System is an Internet-based system for sharing hydrologia data. It is comprised of databases and servers connected through Web services to client application that allow for the discovery, access, and publication of hydrologic data.
• Wetlands data can be accessed through the U.S. Fish & Wildlife Service's National Wetlands Inventory. This service has developed a series of topical maps to show wetlands and deep-water habitats. This geospatial information is used by federal, state, and local agencies, academic institutions, and private industry, for management, research, policy development, education, and planning activities.

Figure 8.8: Map of State Endangered Plant Laws

Credit: USDA Forest Service: Laws and Regulations to Protect Endangered Plants

Why we need it

The Endangered Species Act of 1973 required the identification and protection of endangered species' critical habitats. As a result, assessments and mitigation plans must be created and approved prior to the construction of transmission lines.

Where to find it

• The United States Fish & Wildlife Service maintains a database of rare, threatened, and endangered species for use in GIS applications. The International Union of Conservation and Nature (IUCN) also maintains information on rare and endangered species.

Figure 8.9: Generalized land use and land cover for the Roseau, Minnesota, 1:250,000-scale quadrangle (modified from U.S. Geological Survey, 1998).

Credit: U.S. Geological Survey - Data Series 240    

The map above depicts some of the 21 categories of land use and land cover (LULC) used by the United States Geological Survey. These LULC categories may be used at the state, regional, or local levels. This land use and land cover data was derived from 1970s and 1980s aerial photography.

Why we need it

Land Use and Land Cover (LULC) designations provide general descriptions of the natural and cultural activities taking place within a project area. LULC designations provide the siting planners with information on what type of land use may be in the proposed transmission right-of-way. This information assists the planners in route selection. By comparing current land-use patterns with historic land use patterns, and combining this information with aerial photography, the planners can identify preferred and alternate routes for the transmission lines. Prior to GIS, planners had to manually evaluate this data and the results were subjective. These individual layers of data can be combined easily in GIS and spatially analyzed to arrive at a better understanding of how LULC will impact a proposed transmission line without the uncertainty of manual analysis.

Where to find it

• The most accurate LULC data is digitized from current aerial imagery available from most state or local government GIS clearinghouses (see the section "Individual State, County and Municipal GIS Data"). It is also available from the National Map, but this data has not been updated since the 1980s because of funding issues.
• An article titled "6 Best Sources for Local Land Use/Land Cover GIS Data" from the Plannovation Blog can help you with your search for LULC data.

Figure 8.10: Crossrail Tunnel archaeology dig in London, England

Credit: BBC News

The picture above shows the Crossrail Tunnel archaeology dig in London, England, where archaeologists, surveying the ground at Liverpool Street station in preparation for Crossrail tunneling, have unearthed hundreds of skeletons on the site of a historic mental health hospital. Opened in 1247, St. Bethlehem hospital was the first institution dedicated to mental health patients and is believed to have led to the coining of the word "bedlam." The site now lies beneath what will be Liverpool Street's new Crossrail ticket hall. There are 20 archaeological digs along the Crossrail route and they have to be completed as part of the planning regulations.

Why we need it

Designated historic sites, burial grounds, and archeological sites are windows into our past. As such, the Federal government passed the Historic Sites Act of 1935 to document and preserve sites of national significance. Many states enacted similar legislation. As a result, this information is incorporated into the siting process to avoid impacting these designated sites.

Where to find it

• In many instances, this data is not available for public download because of the sensitivity of the information. In general, the transmission line planner would make a request to a State Historical and Preservation Agency and/or the National Park Service for a listing of such sites in the proposed project area. In many states, this request requires that the user restrict access to the information.

Visual resources include such things as national parks, monuments and battlegrounds, Native American burial grounds, historical sites and buildings, cemeteries and even local neighborhoods, just to name a few.

Figure 8.11: Delaware Water Gap

Credit: NPCA.org

An example of the visual impacts on National Park lands from proposed transmission lines follows, and taken from National Parks Conservation Association:

But views throughout much of the park unit could change substantially if a power company gets its way. Two energy companies—Public Service Electric & Gas (PSE&G) and PPL Electric Utilities—are proposing a serious upgrade to a smaller power line that predates the park, and winds its way through its southern half, crossing the river near the current visitor center. Eighty-foot towers that only occasionally rise above the canopy of maple, ash, and dogwood could soon be replaced by 200-foot towers that would dwarf them. A narrow right-of-way would expand to 300 feet to accommodate the two 500-kilovolt lines, which might require special lighting or bright orange balls for visibility. Asphalt roads would be constructed to provide constant access to what would become a main artery for coal- and nuclear power delivered to New York."

For obvious reasons, the power company’s preferred alternative is to simply traverse the corridor already established in the park—to cover the shortest distance between two points (see map), and to remove the need to purchase privately owned land or claim eminent domain."

Why we need it

The location of a transmission line can impair the line of sight to the visual resources mentioned, or in the instances of local neighborhoods can be a source of unsightly encroachment on neighborhood aesthetics. Transmission lines crossing over or near Federal lands requires a NEPA (National Environmental Policy Act) environmental impact analysis or assessment that includes a visual impact assessment on the Federal lands.

Where to find it

• See the GIS section of the National Park Service website.

Figure 8.12: Protesters outside a Bonneville Power Administration office.

Credit: Zachary Kaufman

Here we see protesters outside a Bonneville Power Administration office in Van Mall, Oregon. BPA proposed a new high-voltage transmission line between new substations in Clarke Rock and Troutdale, Oregon. Residents contend BPA should find less populated areas. Current demographic data is essential in minimizing the impact transmission lines have on neighborhoods, and, at times, the best data may still not be good enough.

Why we need it

Demographic data is essential for planning new transmission lines. It is used to make population projections to identify significant growth areas within a utility's service area. Planners then identify locations for the expansion of transmission lines and electric substations. In addition, both current and future projections of population density in a proposed transmission line project area provide the planner with another source of information on where to propose primary and alternate transmission line routes. In many instances, populated areas are the most significant challenge to siting a transmission line. Residents do not want unsightly overhead transmission lines running through or close to their neighborhoods for fear of property devaluation or concerns about the health implications of electromagnetic fields.

Where to find it

• The U.S. Census Bureau's data website is a source for demographic data for the United States, as well as for individual states.
• In addition, individual county and city GIS websites provide access to land ownership and land parcels. The availability of this data for download varies from county/municipality to county/municipality.

Figure 8.13: Pennsylvania GIS data portal

Credit: Pennsylvania Spatial Data Access

Figure 8.14: North Carolina GIS data portal

Credit: North Carolina GIS Clearinghouse

The two links above take you to Pennsylvania and North Carolina GIS data portals. Once in a state GIS data portal, you have access to many types of GIS information, from simple vector data, such as roadways, to complex raster data in the form of detailed aerial photography. In addition to individual state GIS data portals, make sure you check other state and local sources such as the Department of Transportation, Department of Environmental Protection, and local government GIS data portals.

Why we need it

Sometimes local GIS information is not available from Federal GIS databases, so we need to look elsewhere to find data. Sources for this information can be found on most state, county, and municipal GIS websites. Depending on the level of government accessed, the type and amount of GIS information available will vary, with state GIS websites having the most available data and municipalities having the least, depending on size. Many times, local GIS data may be more up-to-date and more specific to the area you want to study. The combination of federal, state, county, and municipal GIS data sources gives the best opportunity to find the data you need for a specific project.

Where to find it

• The University of Arkansas, as an example, has compiled a clearinghouse for individual state GIS data. This clearinghouse provides access to individual state data that includes many of the topics we outlined above.
• Individual county and municipal GIS data can be accessed through county and local government GIS Internet sites. In addition to the types of information outlined previously, land parcel information and current aerial photography may be available for download from county and municipal geospatial web links. Some of these sites may ask you to register for downloading data. I have registered for many of these sites at no cost.
• Another example of a state geospatial data clearinghouse can be found at the University of Oregon. The UO Libraries maintains a State-by-State listing of geospatial data resources.
• An example of county data can be found here for Union County, NC.
• Here is an example of available California County GIS data.

This activity will give you the skills to find Internet-based data and information, specifically data that can be downloaded and used for siting projects. The activity will focus on identifying and locating data for your state or region and compiling the data into a spreadsheet.

Directions

1. Download the State and Regional Data spreadsheet. You will see that there are columns provided for each of the following points of information: I have included example entries on the first tab as a guide of what your spreadsheet should include. EXAMPLE ENTRIES INCLUDE:
   1. Data Category (5 total: Environmental, Wildlife, Landuse/Landcover, Cultural, and Local GIS Sources)
   2. Data Sub-category
   3. Data Name
   4. Data Format (Vector, Raster, Imagery)
   5. Coordinate System
   6. Horizontal Datum
   7. Description of the data
   8. Data Source
   9. Data Location URL
   10. Metadata Source
   11. Based on what you have learned about data quality, assess the data quality of this data source?
   12. What criteria did you use to assess the quality of the data?
   13. Comments
2. Find, at a minimum, one data source for each of the 5 categories listed in Item #1 above and enter the related information into the spreadsheet (use the "Student Work" tab of the previously downloaded document to show your work). Note that the data categories and data sub-categories are already provided on the spreadsheet. You need to add items 3 through 13 above. THESE ITEMS CORRESPOND TO THE COLUMN HEADINGS IN THE SPREADSHEET. (item #11—"Comments"—only needs to be provided when applicable).
   • When completing your spreadsheet, include, at a minimum, the data sources we outlined previously in this lesson, and any others you have found. Add rows to the spreadsheet if necessary.
   • When listing the website locations, be specific. For example, if you are located in Charlotte, North Carolina, list the URL that would take you to the data for Charlotte, not just North Carolina.
   • In addition, try to find as much available local data as you can. Go to the website for your county or city and see what data is available through their GIS department and list these links in your spreadsheet. (FOR EXAMPLE: LAND USE DATA, ZONING DATA, LAND PARCEL DATA, TAX PARCEL DATA, WATER QUALITY DATA, ETC.)
3. Save your copy of the spreadsheet in Microsoft Excel or PDF format, using the following naming convention:
   
   Lesson8_Spreadsheet_AccessAccountID_LastName.xls (or .xlsx or .pdf)

Having Problems?

If you are having problems, post your questions to "General Questions and Comments: Lesson 8".

Grading Criteria

This activity is graded out of 10 points

The siting of overhead electric transmission lines, underground pipeline, new power plants, and even new highways require many types of information for the analysis in selecting a final corridor or site. Historically, this data had to be gathered manually if it was available. With the advent of computers, GIS software, and the Internet, this data is abundant and readily available. This lesson identified data needs, why it is needed, and where to find it. The exercise of finding data for your particular needs laid the foundation for how to acquire data and catalog those data sources for your future reference and use.

Reminder - Complete all of the lesson tasks!

You have finished Lesson 8. Double-check the list of requirements on the first page of this lesson to make sure you have completed all of the activities listed there before beginning the next lesson.