Alissa Marturano
Data Quality Assignment
1.
For this assignment, I am looking at the last remaining farm in my town of
Wayne, NJ as a possible development site for houses. I am taking a closer look at the safety of building in this location due to the fact that a thorium dump exists across the street. There are several things that I must take into consideration when deciding if the farm is a good place to build. First, I need to assess whether or not the thorium site, or any area around it, is currently contaminated. The positional accuracy of the contaminated area does not need to be very accurate because as long as it in the general vicinity of the farm (about a half a mile), it will be considered a concern. In addition, if contaminated areas are found, I will need to look at elevation of the area to see if runoff would bring contaminants to the farm.
Again, the positional accuracy of the elevation data does not need to be 100 percent accurate as long as it indicates whether or not there is an increased slope around the farm that will bring contaminated runoff to the area. I will also have to make sure that the sewer service area of Wayne covers the farm if I want to build houses there. The positional accuracy of the sewer service area will only matter if the farm lies on the boarder of the area. Finally, I will be looking at any wetlands that could be in the farm area, since there is a stream right next to the farm. The positional accuracy of the wetlands needs to be high (+/- 5 feet) because wetland areas are prone to flooding and I do not want to build a house in an area that will flood often.
2.
To assess the accuracy of the road centerlines surrounding the farm, I used a
1:24,000 color orthophoto from NJGIN. Overall, the road centerlines from the NJ
Roadway Network were closer to the actual position of the road than the
StreetMap USA and Census 2000 Tiger road data were. In fact, the NJ Roadway
Network seemed to bisect the roads on the orthophoto exactly. In some places, the
StreetMap USA and the Census 2000 Tiger roads were actually on top of each other. For example, east of the farm, the NJ Roadway Network lies directly on top of the road’s double yellow lines. StreetMap USA and Census 2000 Tiger linework are both 87 feet east of the NJ Roadway Network line, since they lie on top of each other.

Aerial view of the Road Networks surrounding the entire farm:
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Zoom of the area east of the farm:
Street Map USA
Census 2000 Tiger
NJ Roadway Network
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Street Map USA
Census 2000 Tiger
NJ Roadway Network
The roads south of the farm generally follow the same pattern with the NJ Roadway
Network bisecting the street and StreetMap USA and Census 2000 Tiger roads farther away. Unlike east of the farm, the StreetMap USA and Census 2000 Tiger linework do not lie on top of each other. Instead, StreetMap USA seems to be closer to the correct position since it is 30 ft south of the NJ Roadway Network while the Census
2000 Tiger road is 36ft south.

Zoom to south of the farm:
¯ Street Map USA
Census 2000 Tiger
NJ Roadway Network
I also wanted to check to see how the roads are mapped around curves and through intersections, since the farm lies northwest of a very busy intersection where Black
Oak Ridge Road (US 202) meets Pompton Plains Road (Passaic County 680). The NJ
Roadway Network continues to be the most accurate linework of the three. The
Census 2000 Tiger roads and the StreetMap USA roads lie 60 ft east and 24 ft south of the NJ Roadway Network. Though east of the farm these two roads seem to be on top of each other, south of the farm, they start on top of each other at the intersection and begin to diverge as they move west. Farther west, the Census 2000 Tiger roads move from 24ft to 26 ft south of the NJ Roadwork Network.
Zoom to southeast intersection:
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Street Map USA
Census 2000 Tiger
NJ Roadway Network
In general, the NJ Roadwork Network appears to be more accurate since it is the only road system that was actually mapped on the roads from the orthophoto. Thus, I would use them for my project.

3. To assess the accuracy of the hydrography surrounding the farm, I used a 1:24,000 color orthophoto from NJGIN. The accuracy of the river near the farm is very important because it is directly west of the farm. If the accuracy is poor, we may end up planning to build in an area where the river actually exists or lose areas for homes if a river is shown where it actually isn’t. I looked at two different hydrography layers: one from a New Jersey database and another from the Census 2000 Tiger data.
When just looking at the orthophoto, one can see that the river meandered and created an island. An accurate hydrography layer will show that the island exists and will follow the meandering pattern of the river. The Census 2000 Tiger data and the open water layer from the NJ database (NJ open water) are both polygons and thus should show the island and curves of the river.
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I looked at the layers individually to see how they matched up with the orthophoto before laying them on top of each other. The NJ Open Water layer did acknowledge the presence of the island and followed the bends of the river very accurately. By making the layer 50% transparent, I was able to see if the river was mapped in a place where it didn’t exist. The data was incredibly accurate and stayed within the boundaries of the river.

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NJ Open Water
When looking at the Census 2000 Tiger hydrography layer, the data was quite alarming. It did not show the island, since the entire western half of the river was missing. It would not be correct to say that this data is just out of date and was mapped before the island was created since it was from 2000 and the NJ Open Water layer was from 1986. For the most part, the layer did follow the meanders of the river.
When I made the layer 50% transparent, the river covered the farm 68 ft to the southeast (the widest part). It also showed part of the island as river and covered it 85 ft at the widest part.
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Census 2000 Tiger Rivers

When I put the two data layers on top of each other, the Census 2000 Tiger Rivers layer was much wider than the NJ Open Water layer. At one point, the Census River was 215 ft wide and the NJ Open Water River was only 99 ft wide. In addition, the
Census River meandered farther east than the NJ Open Water River. At this point, the
Census River was 71 ft east of the NJ Open Water River. Again, the Census River failed to include the island or the west part of the river, which the NJ Open Water
River succeeded in highlighting. Because of these accuracy differences, I would use the NJ Open Water River for my project.
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Census 2000 Tiger Rivers
NJ Open Water
4.
To assess quantitative positional accuracy for my data layers, I went back to the metadata of each later and checked for a data quality section that specified the quantitative accuracy. If I could not find this information, I looked at the scale of the map the layer was digitized from and compared it with the National Map
Accuracy Standard. I then assumed the accuracy had to be +/- the designated standard or worse. Since I already determined the road network and hydrography layer that I was going to use, I only assessed the quantitative positional accuracy for those layers. a.
NJ Roadway Network- the metadata from this layer specified the quantitative positional accuracy to be +/- 3 ft. b.
NJ Open Water- the metadata from this layer specified the quantitative positional accuracy to be +/- 80 ft. c.
Wetlands of Passaic County, NJ- the metadata from this layer specified the quantitative positional accuracy to be +/- 80 ft. d.
Known Contaminated Sites in NJ- the metadata did not provide this information, so I checked the scale. At a scale of 1:1000, according to the
National Map Accuracy Standard, the quantitative positional accuracy should be around or worse than +/- 26.67 ft. e.
Sewer Service Area for NJ- the metadata did not provide this information, so I checked the scale. At a scale of 1: 24000, according to the National

Map Accuracy Standard, the quantitative positional accuracy should be around or worse than +/- 40.00 ft. f.
NJDEP Elevation Contours for NJ (20 Foot Intervals) - I could not find the positional accuracy information in the metadata or from a map scale.
Thus, I am not sure of the exact positioning, but from the title I know that it was mapped at 20 ft intervals. However, for my purposes, I don’t think that the qualitative accuracy matters as long as the contours are true to the general slope of the area.
5.
a. Wetlands of Passaic County, NJ- For this layer, I checked the qualitative positional accuracy against the 1:24,000 color orthophoto from NJGIN. The layer, dating from 1986, indicated several areas of the farm that are considered wetlands. The farm was built in 1894 and so it confuses me that the layer suggests that a natural wetland ecosystem should exist in the area. According to the layer’s metadata, the data highlights the county’s tidal and nontidal wetlands. The metadata did not suggest that the wetland areas include areas that flood frequently. Thus, I am not sure whether or not this layer’s qualitative positional accuracy is correct or not, which is problematic for my project’s purposes. It would make sense for these areas to exist if they include areas that flood frequently because of the nearby river. One observation that I made, however, was that the orthophoto showed areas that were mapped as wetlands with an increased ‘soggy’ appearance. This could indicate that the wetland layer highlights areas that have frequent flooding. Regardless, I would need to find out more information about this layer before I used it for my project.
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Wetlands of Passaic County, NJ

b. Known Contaminated Sites in NJ- For this layer, I checked the qualitative positional accuracy against the 1:24,000 color orthophoto from NJGIN. I know the location of the thorium dump next to the farm because I can see it on the orthophoto and know from personal knowledge that it is across the street. I assumed that a dot indicating a contaminated site would be located in the middle of the thorium dump. In actuality, the dot was mapped across the street. Thus the qualitative positional accuracy of the contaminated sites is off. However, I would still use this layer in my project because as long as the contaminated site is in the vicinity of the farm, it should still be considered a concern.
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Zoomed In:
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Known Contaminated Sites
Known Contaminated Sites

c. Sewer Service Area of NJ- For this layer, I checked the qualitative positional accuracy against the 1:24,000 color orthophoto from NJGIN. I really did not have anything to check this layer against because I cannot see the underground sewer system from an aerial orthophoto, and I do not have any personal knowledge of the area to that extent. I would use this layer in my project to make sure that houses built on the farm could receive sewer service. Thus, I assessed the qualitative positional accuracy by taking a zoomed out look at the areas surrounding the farm to see if sewer service was accurate for the housing in the area. By making the layer 50% transparent, I was able to see the houses underneath and make sure they had sewer service. It turned out that almost all of the area around the farm and including the farm had sewer service available. Thus, I can assume that the qualitative positional accuracy is high and can use this layer for my project.
¯ d. NJDEP Elevation Contours for NJ (20 Foot Intervals) - For this layer, I could only
Sewer Service Area
NJ Open Water check the qualitative positional accuracy against my own personal knowledge of the area. I live rather close to the farm and have visited it and passed it countless times throughout my life. I know that east of the farm there is a huge hill and the farm lies at the bottom of this hill. If the contour lines followed this description and were very close to each other to the east of the farm, then I could assume that the qualitative positional accuracy is high. After mapping the contour layer, the data did coincide with my description. Thus, I could use this layer in my project to assess whether or not runoff from the thorium dump will enter the farm.

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6.
a. Wetlands of Passaic County, NJ- The quantitative accuracy was +/- 80 ft and
Known Contaminated Sites
Elevation the qualitative accuracy could or could not be off, depending on further research on the meaning of ‘wetland.’ Even if the qualitative accuracy was correct, I think that a quantitative accuracy of +/- 80ft is not good enough to determine where to build houses. If I built a house in an area that the data layer does not consider to be wetland but in reality is, I would create many flooding problems for the future homeowner. I feel that quantitative accuracy for this layer should be more along the lines of +/- 5 ft. Again, as I mentioned before, I would really need to do more research on this layer as well as visit the farm to understand the environment better. b. Known Contaminated Sites in NJ- The quantitative accuracy was +/- 26.67 feet and the qualitative accuracy was not great, but still acceptable since the site was mapped across the street from the actual area. I feel that the mapped location of the site is close enough to its real location. I would still use this layer in my project because, as I stated before, as long as the contaminated site is in the general vicinity of the farm, it should still be considered a concern. c. Sewer Service Area- The quantitative accuracy was around +/- 40 ft and the qualitative accuracy was high since the entire farm was covered by the layer. The farm was not on the boarder of the sewer service area, so the fact that the

quantitative accuracy is +/- 40 ft does not affect my site. Thus, I would use this layer in my project because I just needed to know if the farm had access to a sewer system, which it does. d. Elevation- the quantitative accuracy was unknown and the qualitative accuracy was high based on my own personal knowledge. I would use this layer for my project because I just need to know the general slope of the area around the farm and around the contaminated site to see if runoff to the farm would bring contaminants with it. Thus, I do not believe that, for my purposes, the quantitative accuracy needs to be high, and using this layer should work fine for my project.
7.
a. NJ Roadway Network- The metadata for this layer indicated that the layer was complete except for private roads. These were not mapped or included in the layer. Fortunately, for my project, private roads were not a part of the road system near the farm. When I looked at the layer on my map, I could conclude that the layer was complete since all roads surrounding the farm were mapped and the names of each were given in the attribute table. b. NJ Open Water- According to the metadata, this layer was completed for all lakes, ponds, tidal waters, rivers, reservoirs, and bays in the county. When I looked at the layer in my map, I could conclude that the layer was complete since it covered the river near the farm perfectly. In addition, the attribute table gave me the information that I would need for my project. c. Wetlands of Passaic County, NJ- the metadata of this layer indicated that the layer was completed for the entire county. When looking at the layer in my map, it is difficult for me to tell whether or not the layer is complete because I really don’t have anything to check the data against. Therefore, I do not know if it left out certain areas of wetland from the farm. I would assume that the layer is complete since it is stated in the metadata. d. Known Contaminated Sites- According to the metadata, around 50 sites were not included in the GIS layer due to poor address descriptions or were sites that represented several cases and could not be denoted by one point. Fortunately, for the small area that I looked at, the layer was complete, since the thorium dump was mapped as a known contaminated site. In addition, the attribute table showed me the name, address, and type of contaminated site it was, which I would need for my project. e. Sewer Service Area- The metadata of this layer indicated that the layer is complete, but will be periodically updated since it is a part of the Continuing
Planning Process. When looking at the layer in my map, I can conclude that the layer is complete because it covers the entire farm area and the attribute table tells me all I need to know about the service for my project.

f. Elevation- The metadata of this layer indicated that the completeness of the layer is unknown. When looking at the layer on my map, I can conclude that the layer is complete based on my own personal knowledge. The contours show a hill east of the farm and that the farm is located on a large patch of flat land. This coincides with my personal knowledge. In addition, the attribute table has the elevation information for every contour line. When I downloaded the data layer, it covered the entire state of New Jersey, so I would assume that the layer is complete.
8.
The currency of each of my layers was different. I found this information from the metadata of each of my layers. a.
NJ Roadway Network- this data is from 2005, which is relatively up to date, and since no new roads have been put in since then, this data is credible. b.
NJ Open Water- this data is from 1986. At first, I would have assumed that this data is out of date, since the river could have meandered in 20 years or building in the area could have had some influence on it. But, after comparing it to an orthophoto from 2002, I concluded that this data is still up to date and credible since it covered the river exactly. c.
Wetlands in Passaic, NJ- this data is from 1986. Based on my personal knowledge of the farm, I am not aware of any wetland ecosystems on the farm. Again, I would need to do more research on the layer to see if the term wetland included areas that are prone to flooding. Thus, I am still undecided whether or not the data is up to date and credible. d.
Known Contaminated Sites- this data is from 2005, which is relatively up to date. Since I know from personal knowledge that the contaminated site is around the area referred to in the layer, I believe that this data is credible. e.
Sewer Service Area- this data is from 2006. Since I cannot confirm whether or not the sewers exist under the farm location, I have to rely on the currency of the data to assume that it is credible. Since 2006 is pretty recent and there have been no major installations of sewers since then, I believe that this data is up to date and credible. f.
Elevation- this data is from 1987. Though building in the area can effect elevation by making an area more or less steep, I still believe from personal experience that the data is up to date enough for my purposes.
9.
a. NJ Roadway Network- In the attribute table, the name of the street was present, but the address ranges were not. Fortunately, for my project I don’t need to know the address ranges; the street names will be sufficient.

b. NJ Open Water- the attribute table did not include the name of the river, but it did tell me its area per square kilometer and the fact that it is labeled as a “stream and canal.” I believe that, for my project, the attribute data is adequate because I will only want to know the area per square kilometer. c. Wetlands in Passaic, NJ- the attribute table told me the types of wetlands on the farm as well as their areas. I believe that this information is adequate for my project because, if I decide to use the layer, I will need to know how large the wetland area is. Then, I will know where I should and should not build houses. By knowing the type of wetland, I can research the characteristics of that wetland to see how much flooding may occur. The attribute table said that the wetlands on the farm were considered agricultural wetlands. d. Known contaminated sites- the attribute table told me the name of the site, the address of the site, whether or not it is active, the category it falls under, and what type of contamination occurs at the site. This information is adequate for my project because I need to know if the site is still active and what contamination occurs there. Then, I would know what to look for when testing for groundwater contamination or other potential contamination possibilities brought by runoff.
The site is still active and it says that the thorium pollutant is being released into the groundwater as well as other media. e. Sewer Service Area- the attribute table told me who is in charge of building and maintenance of the sewer system as well as the water management plan that the area belongs to. This data is sufficient for my project because if I build homes in the area, I will have to work with these people to make sure that sewer connections to the new houses are installed in a proper way. f. Elevation- the attribute table told me the elevation of each contour line. This data is adequate for my project because I need to know if the farm is at the bottom of a steep slope that will bring contaminated runoff from the thorium dump. By evaluating each contour elevation, I will be able to understand the topography enough to see where the runoff in the area will flow.