then track maintenance procedures due to an excessive build-up of sewage waste in the area. In 2006 the RMT agreed waste tank and clean-out developments at Northern Rail's Heaton TMD in 2006 with GNER, and new clean-out procedures at all other depots, to solve an ongoing dispute over the previous 18 months. By 2011, the European Union had begun a formal investigation to see whether trains composed of such carriages were breaking EU environmental and health laws, although the Environment Agency confirmed that train companies claimed special exemptions to dump waste on the track. In 2013, Transport Minister Susan Kramer branded the practice "utterly disgusting" and called on the industry to take action. ATOC responded by stating that, as all new vehicles had to be fitted with compliant toilet tanks, withdrawal of the HSTs by the end of 2017 would solve the problem. The use of HSTs without retention tanks continued after the end of 2017, but sets being transferred to ScotRail and shortened HST sets retained by GWR are being fitted with retention tanks. ScotRail operated brown waste discharging sets until the COVID-19 pandemic facilitated cuts to service in April 2020. Train formations HST vehicles Original formation The original coaches were delivered in HST sets for Western Region (Class 253) with Trailer First (TF), Trailer Restaurant Unclassified Kitchen (TRUK), Trailer Second (TS), and Trailer Buffet Second (TRSB) cars in the formation TF-TF-TRUK-TS-TRSB-TS-TS. Complaints from guards about engine noise in the guards' compartments in the power cars led to the Trailer Guard Second (TGS) in 1980, based on the TS but with the end vestibule and one seating bay replaced by a guard's compartment. This replaced the last TS in all sets from 1980 onwards. Sets delivered for Eastern and Scottish Regions (Class 254) contained eight coaches, originally in the formation TF-TF-TRUK-TS-TS-TRSB-TS-TS. The TRUK cars were quickly replaced by a TS on the Western Region and most had been replaced on the Eastern Region by 1985 (many later rebuilt into loco-hauled buffet cars). TRUB cars (Trailer Restaurant Unclassified Buffet) were built from 1978 to replace the TRUK cars, these were reclassified as TRFB (Trailer Restaurant First Buffet) from 1985 on the Eastern and London Midland Regions and from 1989/90 on the Western Region. The original interiors were fitted out fully carpeted with InterCity 70 seats. First Class had orange and red stripes on both carpet and seating, whilst Standard Class