Mountaineer Gas has filed rate adjustment requests with state regulators that would increase monthly bills for residential customers.The company has proposed a change in purchased gas cost rates and monthly pipeline demand changes, resulting in a monthly increase of about $12.51, or 15.56% beginning Nov. 1, according to a news release from the company.The news release said the filing was prompted by “significantly higher transportation and storage costs from pipeline companies” which are passed down to customers without profit for Mountaineer.The company also announced a request for an infrastructure replacement and expansion program rate increase to go into effect Jan. 1, which would translate to an extra $1.55 per month on average