East Ascension Consolidated Gravity District, Monument Construction

According to the National Geodetic Survey (NGS), Louisiana is known to be an area with benchmark discrepancies resulting from subsidence and a rise in sea level. Ascension Parish has an unreliable network that has left decision makers with a lack of information when it comes to planning for future growth. SJB Group, LLC (SJB) as subcontractor to CH2MHill, provided technical assistance to the USACE (New Orleans District) and East Ascension Consolidated Gravity District in establishing a control network. The intention of the project is to develop a solution to the out-of-date and unstable vertical benchmarks by installing and recording elevations on 79 monuments.

Specific activities conducted in this research and reconnaissance phase of work included the following:

  • Assemble forty (40) monuments across Ascension Parish
  • After monuments are in place, perform primary and secondary GPS network static observations on all 79 monuments
  • Record and present all data to the USACE, CH2MHill and Ascension Parish
  • SJB determined the best use within the study area and associated floodplain by providing a solution for inaccurate benchmarks

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Driving Benchmark Rod Until RefusalSurvey Monument Cover OpenSurvey Monument Cover Closed


Ascension Parish, LA