Hydrographic Survey – Refinery, Houston, TX
CRA has carried out depth surveys at this refinery for over 18 years. We currently carry out such services on the majority of the private docks on the Houston Ship Channel and in Texas City. We perform both condition surveys (quarterly) and pre-dredge and post-dredge surveys (typically annually) at the docks. This consists of surveying each of the 6 main ship berths, each approximately 1200 feet long with transects every 50 feet apart, using real time differential GPS based on Trimble receivers using signals from the U.S. Coast Guard.
Depths are measured with an Innerspace model 448 single frequency fathometer on our 19 foot center console survey boat. Data is logged on a notebook PC running “Hypack” software. The data is edited in our Houston office and imported into a Bentley Microstation v8 CAD file using the Corps program “Alisound” to produce a plan view bathymetric chart. We also produce cross-sections (also in Microstation) and a volume computation of the amount of material removed, or to be removed using the average end area method.