Report of Research, Field Investigation and Survey of Robert D ...

5.3 Geo-referencing
In order to meet project requirements that the survey be geo-referenced, a five station GNSS
session was observed using one dual frequency and four single frequency receivers. The 7 hour
data file from the dual frequency observation was submitted to the Precise Point Positioning
Service (PPP) provided by Geodetic Surveys of Canada for processing. The absolute accuracy
for the results was 0.02m at the 95% confidence level. Two new concrete pins (Stations 1200 and
1202) were established in the general project area, and temporary nails were set at the Road
Allowance between Lots 13 and 14 and also at Baseline Road. Another nail was set at the
Concession 4 road, strictly to provide better geometric structure to the network. A four hour
GPS session was observed in the field, and downloaded and processed using Spectrum v4.2.2
software. For preliminary processing we used the value for Station 1002 as measured relative to
Station 2 from Plan 51R-34310 (As determined by RTK measurements - see para. 5.4) as a fixed
base point. The results of this survey were excellent, with worst-case 95% confidence error
ellipses of 0.006m for the stations. Co-ordinates are for UTM Zone 17 (NAD83-CSRS).
Elevations are also based on the PPP observation and processing and are orthometric, referred
to the CGVD28 datum.
During our time on site during August 2013, a second 6.5 hour dual frequency GPS observation
was made over Station 1202 to verify our results. After processing by PPP, the results (with
estimated 0.025m accuracy at the 95% confidence level) agreed with the previous value within
0.02m.
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