Hilcorp Natural Gas Leak from 8-inch Pipeline

Location Cook Inlet between Platform A and Nikiski. (Lat/Long: 60.776367, -151.43365)
Product/Quantity The gas is processed dry natural gas (98.67% Methane), providing fuel gas to four platforms in Cook Inlet. The exact amount of gas released to water/air is unknown at this time. Line pressure has consistently been decreased since the leak was first reported. As of March 13, Hilcorp reported the line pressure was reduced to 145 psi with an estimated leak rate between 193,000 to 215,000 cubic feet per day.
Cause The cause of the leak is unknown at this time and is being investigated.
Time/Date of Incident Unknown


May 1 PHMSAís deadline for Hilcorp to stop the leak.
March 23 ADEC provides response to Hilcorpís Environmental Sampling and Monitoring Plan Summary Report for sampling period #1 with initial comments from review. ADEC continues to review the report more fully.
March 22 Hilcorp submits Environmental Sampling and Monitoring Plan Summary Report for sampling period #1 ending on March 21, 2017.
March 14 ADEC publishes SITREP#4.
March 14 ADEC issues letter detailing preliminary initial approval of Hilcorp to commence the sampling and monitoring plan as described.
March 8 Hilcorp submits environmental sampling and monitoring plan to ADEC. Hilcorp also submits letter regarding the pipeline shutdown contingency plan which details Hilcorpís intent to submit the pipeline shutdown plan to PHMSA, as required by PHMSAís Notice of Proposed Safety Order.
March 3 PHMSA issues Notice of Proposed Safety Order.
March 1 ADEC publishes SITREP#3.
February 27 Center for Biological Diversity issues Notice of Intent to Sue.
February 27 ADEC sends letter to Hilcorp, again asking for a sampling and monitoring plan to be submitted by March 8 in order to determine environmental impacts. ADEC also requests pipeline shutdown plans to be submitted by March 13.
February 24 ADEC issues a Notice of Violation to Hilcorp, stating the company is releasing a hazardous substance and needs to control it.
February 21 ADEC publishes SITREP#2.
February 20 Hilcorp responds to ADECís February 10 letter, stating the spill is not unduly harming the environment and the company will not be able to safely stop the leak until the ice conditions improve. Hilcorpís written response does not adequately address monitoring plans, as requested.
February 15 ADEC publishes SITREP#1.
February 15 Citizen-based non-profit organization, Cook Inletkeeper, sends Notice of Intent to Sue Hilcorp under the Clean Water Act.
February 14 ADEC requests Hilcorp conduct overflights of leak site.
February 10 ADEC sends Letter of State Interest requesting information about stopping the leak and plans for monitoring and mitigation in the interim until pipeline repaired.
February 9 ADEC informs Hilcorp of jurisdiction over the discharge of any hazardous substance in Alaska.
February 7 Cook Inlet Regional Citizens Advisory Council engaged.
February 7 Leak reported by Hilcorp; USCG, NRC, ADEC, PHMSA notified.