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Geodetic Control Requirements
On May 15, 2007 the Board of County Commissioners adopted geodetic control requirements that, among other things, require the regulated community to provide coordinate points as part of the plan review process. Once provided, said coordinate points are incorporated into the County's GIS database for use in a variety of data analysis and data retrieval applications.
To view the codified amendments, please click here. To view the GIS Work Group's original proposal that led to the adoption of the geodetic control requirements, please click here.
In general, the geodetic control requirements necessitate the following to be provided on as-built plans submitted to the Department of Public Works:
1) Road as-built plans - A minimum of three coordinate points, including every stormdrain inlet, manhole, and stormdrain outfall shown on the plan.
2) Stormwater Management as-built plans - A minimum of three coordinate points, including every stormdrain outlet, manhole, and stormwater management pond riser structure shown on the plan.
3) Lot grading as-built plans - A minimum of three coordinate points, including any well installed to service the new construction, one corner of every constructed structure, and one property corner.
4) Sanitary Sewer as-built plans - A minimum of three coordinate points, including every manhole and pump station shown on the plan.
Accuracy Standards
Cecil County desires GIS mapping level accuracy for the coordinates, not necessarily survey level accuracy. The GIS Work Group has further concluded that requiring survey level accuracy will not be possible until a densification of monumentation is completed within the County.
The GIS Work Group has decided to utilize a transitional approach in terms of accuracy. This approach, as outlined in the table below, would enable the regulated community to transition (i.e. in terms of equipment needs, cost proposals, etc.) with the proposed upgrades to the monumentation network, and thereby move from mapping level accuracy (today) to survey level accuracy in the future.
If a certain firm or member of the regulated community can provide accuracy at a level greater than the minimum required, then that increased accuracy would be welcomed. This transitional approach to accuracies is not intended to "dumb down" the submissions of any firms able to work at the higher accuracies.
Currently, the County's accuracy standards are at Level 8, as explained in the table below.
| Level |
Type
|
Accuracy Classification
|
Examples
|
Timeline for implementation
|
8
|
General GIS
Mapping
|
Equal to or less than
11 meters
|
|
Once amendments are
adopted by BOCC |
7
|
General GIS
Mapping
|
10 meter
5 meter |
Location & inventory
data gathering for GIS
|
6 months to a year
after adoption
|
6
|
General GIS
Mapping
|
2 meter
1 meter |
Location & inventory
data gathering for GIS
|
One to two years
after adoption |
5
|
Survey level quality |
5 decimeter
2 decimeter
1 decimeter |
|
Once a densification
of monumentation
is complete |
4
|
Survey level quality |
5 centimeter |
3rd Order
Control Points |
To be determined
in the future |
3
|
Survey level quality |
2 centimeter |
2nd Order
Control Points |
|
2
|
Survey level quality |
1 centimeter |
1st Order
Control Points |
|
1
|
Survey level quality |
5 millimeter |
"A" Order
Control Points |
|
0
|
Survey level quality |
2 millimeter
1 millimeter |
|
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Providing the Coordinate Point Information
The coordinate points must be provided as part of the as-built plan submitted to the Department of Public Works, and all coordinates must be in Maryland State Plane NAD83 meters. The coordinates can be provided on the as-built plans themselves or can be provided on a separate worksheet. Examples of separate worksheets can be obtained by clicking on the links below:
Lot Grading as-builts
Road as-builts
Sanitary Sewer as-builts
Stormwater Management as-builts
Questions
Please direct questions regarding the geodetic control requirements to the County GIS Coordinator at 410-996-5220. Questions regarding the actual as-built plans themselves or other requirements of as-built plans should be directed to the Development Services Division of the Department of Public Works at 410-996-5265.
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