Triad Engineering

GSA Schedule
TRIAD Listens, Designs & Delivers
Winfield, WV

This project included observation of alignment pins on the Winfield Dam and New Lock Chamber to determine if any movement had occurred since construction.  In addition, Triad is tasked with updating existing survey control monuments to the NAD 83/NAVD88 datum to comply with new US Army Corps of Engineers' Comprehensive Evaluation of Project Datums (USACE CEPD) guidelines. 

The project began with a reconnaissance of existing USACE survey monumentation to determine if any monuments had been damaged or removed during construction.  It was discovered that two monuments were destroyed during construction of the new lock chamber.  It was determined that excavations in the vicinity of a third monument had disturbed its location.  Therefore, after completing the GPS survey, three new control monuments were established.

Utilizing GPS and traditional equipment, Triad surveyed existing control points and set up the project in the NAD 27 coordinate system and the NAD 83 coordinate system.  Data adjustments produced results that matched the existing control coordinates very closely.  The GPS survey network included multiple extended observations at each control point with various instruments to help eliminate possible equipment errors.

Winfield Locks & Dam - Winfield, WV

Utilizing the Real Time Kinematics method of GPS surveying, observations were taken on 90% of monitoring pins on the Locks and at downstream points along the dam.  Each point was occupied for a 5 minute session, then the rod and antenna were spun 180° on the same point and a second 5 minute occupation was completed.  Each point was later post processed against the RTK base station and the other four static units that were running at that time.  This resulted in each monitoring point having eight baselines from existing control points to it.  The typical configuration consisted of a static unit or base station operating at each of the control pins upstream and downstream of the point.  A third and fourth base station was located on a two additional control points that provided for the best geometry to that point.

To evaluate vertical data, two existing NGS monuments were found within a 2-mile radius of the project.  Bench levels were run from these monuments through the project site, including three existing points on the new locks.  Two new benchmark disks were set at the gate monoliths of the new lock chambers for future use.

When all data adjustments were complete, the process of computing station and offsets and making the necessary comparisons got underway.  The data was imported into Microsoft Excel and formulae were used to calculate the station and offset for each monitoring point.  A review of the data found no significant movement in any of structures in the vertical or horizontal plane. 



Winfield Locks & Dam

Winfield, WV
USBGC Logo - Geoprofessional Business Association