Varzo (VB) system

Building of two steel pressure pipes belonging to the ENEL hydroelectric plant of Varzo I (VB) and relative support and anchoring civil works – Execution and construction design.

Cairasca branch

Steel penstock of inner diameter 1200 mm and thickness between 8 mm and 22 mm, with blocked vertices, with telescope-shaped movement joints, with intermediate support pins and running in the open air.

Length of approximately 950 m and hydraulic drop of about 455 m.

Completed by a terminal distribution conjunction with the two production groups, including fork-junctions between the 1200 mm pressure pipe and the 800 mm branches.

The penstock includes a pipe-bridge spanning approximately 39 m, with a square frame transversal section with overall encumbrance 3 x 3 metres. The structure is made of a space reticular beam divided into 3-metre long blocks. By means steel pin supports, spaced 6 metres, the pipe lies on the lower transversal beams of the reticular structure.

The bridge is supported up-stream by a reinforced concrete abutment, built on the left bank of the torrent, and down-stream by the anchoring block of the penstock; at both supports structures were built, which will restrain the nodes connecting the lower beams and the vertical posts, in order to block the movements of the bridge, allowing rotations. The metal elements are made of CORTEN steel. At the sides of the pipe there are two grill-floor walkways, used for maintenance operations.

Diveria branch

Steel penstock of inner diameter 1000 mm and thickness between 8 mm and 10 mm, with blocked vertices, telescope-shaped movement joints, intermediate support pins and running in the open air.

Length of approximately 140 m and hydraulic drop of about 35 m. Completed by a terminal distribution conjunction with the production group.

Services provided: Execution design and construction drawings for steel works and civil works.

Client: PARESA S.p.A.

Site: Municipalities of Trasquera and Varzo, province of Verbania-Cusio-Ossola.

Year: from 2009 to 2011

Cost of works: 7.0 million Euros