The purpose of the Platform Removal Observer Program, commonly known as PROP, is twofold. First, the program functions to protect sea turtles and marine mammals from impacts of underwater explosives used in the platform removal process. Second, the program assesses the impacts of underwater explosives on these protected species.
The following list describes the observer's role:
Document sightings of sea turtles and marine mammals both before and after detonations.
Recommend delays in detonating explosives when sea turtles and marine mammals are present.
Record the condition of observed animals.
Coordinate retrieval of impacted animals for medical examination, rehabilitation, and necropsy.
Program data indicate, approximately 2,860 structures were monitored from 1987-2018. According to Bureau of Safety and Environmental Enforcement data, at the end of 2018 there were roughly 1,860 active platforms in the U.S. Gulf of Mexico.
Since 1987, federal regulations required the use of National Marine Fisheries Service (NOAA Fisheries) approved observers to perform biological monitoring at the explosive removal of oil and gas structures in the U.S. Gulf of Mexico. In that year, the Platform Removal Observer Program was initiated to meet this requirement.
Procedures for Scheduling Observers
- Contact the Program Manager or Logistical Coordinator to request an “infosheet”, within a month or two prior to the platform removal date.
- Complete and return the “Infosheet”. Be sure to send either an electronic or hard copy of the application you submitted to Bureau of Ocean Energy Management for a permit to use explosives to remove structures in federal waters (or other government agencies for removals in state waters).
- An Agreement is prepared and 24-hour mailed to the individual listed on the "Infosheet" as the signatory. This agreement assures reimbursement to NOAA Fisheries for costs associated with performing biological monitoring at the structure removal.
- Sign and return the hard copy of the Agreement via 24-hour mail.
- Provide periodic updates regarding scheduling of the offshore structure removal to facilitate scheduling of observers.
Fixed Offshore Platform
There are numerous types of offshore oil and gas structures including platforms, caissons, etc. The Platform Removal Observer Program, entails all of these although the number of platforms removed with explosives annually exceeds all of the other varieties.
A typical offshore fixed platform has several major components. The “deck” is the uppermost part of the structure located above the sea surface. The deck is welded to the “jacket” which extends from about 10 feet above sea level all the way down to the sea floor. Steel pilings are driven through the hollow corners of the jacket into the sea floor to depths that may exceed 100 feet. It is these pilings that secure the platform to the sea floor and enable it to withstand the forces of winds and seas. Production platforms also have well conductors which extend down the drill holes. It is through these conductors that oil and gas are extracted from deep within the earth.
How are Offshore Structures Removed?
Explosives account for roughly half of all removals. There are a variety of methods and equipment used to perform explosive removal of offshore structures. In the most common platform removal method, torches are used to cut the deck from the jacket which is then lifted from the platform and placed on a materials barge. The interior of the pilings must be clear and unobstructed to permit the placement of explosive charges. Sediment is sometimes found in the lower section of the pilings below the sea floor. A water jet is used to clear out the sediment. Explosives are then lowered inside the hollow pilings to a minimum depth of 15 feet below the sea floor which is a requirement of the Bureau of Ocean Energy Management, the agency with jurisdiction over oil and gas operations in federal waters. The salvage vessel, typically a derrick barge, is then backed off a safe distance, and explosives are detonated. Pilings and conductors are pulled using the large crane on the barge, and the jacket is then lifted out of the water. Platform components may be returned to shore for scrapping, refurbished for reuse, or they may be returned to the sea at a designated artificial reef site.
In fall of 2006 monitoring protocols were revised in a new Biological Opinion for Explosive Removal of Offshore Structures. Monitoring requirements are summarized in Table A-1, A-4. All monitoring must be conducted continuously. An updated Biological Opinion is anticipated in 2019.
Monitoring is performed from vessels, barges, or platforms provided by the oil or gas company responsible for structure removal. No nighttime blasting is permitted. If marine protected species, or MPS, such as sea turtles or marine mammals are observed within the impact zone during the last 30 minutes of a pre-detonation surface survey, the survey will continue for an additional 30 minutes. This process continues until no MPS are observed within the impact zone. Immediately upon completion of the pre-detonation surface survey, the pre-detonation aerial survey is initiated, if one is required. If MPS are observed during the pre-detonation aerial survey, the survey is aborted and opportunistic surface monitoring is conducted for the next 30 minutes. The entire pre-detonation aerial survey is then repeated. This process continues until no MPS are observed within the impact zone during the pre-detonation aerial survey. Immediately upon completion of the pre-detonation aerial survey, if no MPS were observed, then an all clear message will be given and explosives will be detonated immediately. The aerial survey must continue uninterrupted until explosives are detonated. If explosives cannot be detonated for an extensive period of time, then the aerial survey will be terminated. Surface monitoring will continue followed by repeating the entire aerial survey when explosives are ready for detonation. Divers should recover any injured or dead sea turtles or marine mammals observed.
From 1987 through 2018, 13 sea turtles were observed as "taken" under these regulations. Four were killed (four loggerheads and one Kemp's ridley), four were injured (three loggerheads and one unidentified), and five were stunned/lethargic (three Kemp's ridleys, one loggerhead, one green). NOAA Fisheries observers reported no marine mammals were injured or killed by explosives.
Risk Assessment Guide
Aerial and surface observations of sea turtles and dolphins can be viewed in the Risk Assessment Guide which may be used to assess the likelihood of encountering marine protected species in the Gulf of Mexico.
Megan Kesterson, Program Manager
Samantha Peterson, Logistical Coordinator
Risk Assessment Guide for Explosive Platform Removals