GMP: Irene update, Marshfield Dam

As of 10:30 am on Monday, Green Mountain Power has roughly 2,800 outages throughout its service territory, down from 12,000 last night. The bulk of the outages are in Washington and Windham Counties. In Washington County, about 1,300 GMP customers are without power largely due to the Waterbury substation being down as a result of flooding last night. The remaining outages are scattered throughout Addison, Bennington, Caledonia, Chittenden and Windsor Counties. See www.vtoutages.com for updated details.
Last evening, rising waters levels put the Marshfield dam at risk, which necessitated the evacuation of residents downstream. Fortunately, the water level stabilized at the Marshfield dam and we did not have to take the emergency action of releasing overflow waters . Those residents who evacuated are now free to return home.
Green Mountain Power crews and an additional 100 2-person crews brought in from out of state are continuing to work to restore power to those who are experiencing outages. While crews are working to respond to outages as quickly as possible, it may be a few days for power to be restored in some place as a result of the heavy flooding and road conditions.Green Mountain Power is down to 5600 customers without power as of 7 pm Sunday, from a high of 11,000 earlier in the day. Most of the early outages were in southern Vermont, and by 6 pm power had been restored to all but 2800 customers. As winds picked up in northern Vermont, however, outages began increasing, with 3000 new outages in Chittenden county in the past hour.
The heavy rains have significantly increased water levels behind GMP’s dams, reaching levels that are potentially dangerous. At our Marshfield dam, record water levels are approaching the top of the dam. Because it is an earthen dam, water cannot be allowed to flow over its top. We are prepared to take emergency measures to protect the integrity of the dam. If necessary, the flow of water through the dam will be increased, which will result in greater flows of water all along the Winooski River. This action may be unavoidable in order to protect public safety and the integrity of the dam. However, if rains continue to abate and the rising of water levels slow, this action may not be necessary.
GMP notified Vermont Emergency Management, the Agency of Natural Resources and other state officials. As a precaution, people living immediately downstream of the dam are being evacuated.
While GMP said it has made significant progress restoring service, flooded roads are preventing GMP line crews from reaching some problem areas. GMP will do repairs as soon as it is safe and accessible to do so. GMP expects, in some instances, it will be at least a day before flooding recedes sufficiently to be able to access these areas.
After the storm ends tomorrow, we will do a complete assessment of damage to GMP’s system and determine approximately when customers will have power restored.
GMP has brought in an additional 200 lineworkers and tree trimmers to assist with restoring power as quickly as possible.
Green Mountain Power. 8.29.2011