Handover of construction and installation works to Moscow United Electric Grid Company PJSC

At the end of last year NNIAT LLC completed and handed over to Moscow United Electric Grid Company PJSC construction, installation and commissioning works, materials supply for the project “Reconstruction of 110kV overhead line "Serpukhov-Zapovednik with tapping", 35 kV overhead line "Serpukhov-Reka", 5 commissioning and start-up complex for "South Electric Grid", a branch of PJSС "MOESK" located in Serpukhov district, Moscow region, along the main highway.

The scope of works included:

• early works (earthworks, arrangement of temporary access roads, cutting and surfacing of road pavement);
• dismantling of 110 kV overhead line “Serpukhov-Zapovednik”, “Serpukhov-Putshino” and 35 kV overhead line “Serpukhov-Reka” of a total length of 9,525 km (dismantling of cables, overhead ground-wire cables, reinforced concrete and steel supports — 70 pcs.);
• construction of 110 kV overhead line “Serpukhov-Zapovednik”, “Serpukhov-Putshino” and 35 kV overhead line “Serpukhov-Reka” of a total length of 8.349 km (installation of metal and precast concrete foundations for supports, installation of multisided and lattice towers - 44 pcs., suspension of wires and cables);
• arrangement of complex overhead crossings of electrified railway (Moscow Railway) and highway (Simferopolskoe shosse);
• installation of fiber optic cable (suspension of overhead ground-wire cables, optical cable, laying of fiber optic cables in the pipeline);
• dismantling and construction activities at the tapping work area of 110 kV overhead line of 2.1 km distance with 10 supports replacement;
• rehabilitation of disturbed lands; 
• commissioning works.

The work was performed in 2 steps:

Step 1. Activities on the reconstruction of 110 kV overhead line “Serpukhov-Zapovednik with tapping”, 25kV overhead line “Serpukhov-Reka" in Serpukhov town from Serpukhov substation to the support in design stage No.22 of total length of 3,24 km; 

Step 2. Activities on the reconstruction of 110 kV overhead line “Serpukhov-Zapovednik with tapping” from the support in design stage No.22 to support No39/15 in design stage on the territory of Serpukhov district outside the city boundary, of the total length of 3,26 km.

54 supports have been installed, including:

• 24 – lattice towers, that were previously widely used for overhead lines erection
• 30 – multisided supports, that have recently started to be used for overhead lines erection. Among multisided supports 15 supports were used for intermediate suspension of wires at 110 kV two-circuit overhead line and 15 anchor-angle supports for suspension of wires at 110 kV, 35 kV three-circuit overhead line, where two circuits are used for 110 kV overhead line. 

The installation of the latter was the most challenging, as both the supports and supports foundation are not related to series manufactured products, their design varies depending on the facility, and therefore works on the erection of such supports are customized. 

Replacing the existing 110, 35 kV overhead lines, the newly erected lines are three-circuit overhead lines along the distance of 2.076km and two-circuit overhead lines along the distance of 4.221 km. The rest is one-circuit overhead line.

Suspension of АС 240/32 steel reinforced aluminum non-insulated wire was performed at 110 kV overhead line, and suspension of АС 120/19 wire at 35 kV overhead line. 

During the erection of 110, 35 kV overhead line, the installation of fiber optic cable with suspension of optical cable, integrated in ground wire cable OKGT-s-1-24 (G.652)-14,4/66 and fiber optic dielectric self-supporting cable OKK-0.22-24.

Prior to the erection of new 110, 35 kV overhead line along the road were dismantled, removed and disposed:

• supports
• foundations
• cables
• wires
• insulators
• existing 110, 35 kV overhead lines hardware.

Along the distance of 4,7 km of overhead line construction, the areas are naturally flooded. On the territory of the city there is backfilled soil with construction waste and scrap brick of 0,5-0,8m thickness. Outside the city – the backfilled soil with construction waste and scrap brick of 0,2-0,3m thickness.

Works, especially in the city are, were performed in space limited environment. During work performance in built-up part of Serpukhov city, space limited environment was caused by the following factors:

• residential and/or industrial buildings, as well as conservation green planting in close vicinity to the work area;
• space limited environment for material storage and/or impossibility to store materials at construction site to ensure appropriate provision of materials at work areas.

Works on the reconstruction of 110 kV and 35 kV overhead lines “Serpukhov-Reka” were mainly performed near the existing 110 kV overhead lines.

Along the highway, the newly built 110 kV overhead line crosses Moscow electrified railway of Russian Railways OJSC (Serpukhov-Oka railroad haul), Simferopolskoe shosse (Central Russia Federal Highway Administration), main gas pipelines, 220 kV, 35 kV, 10 kV, 0,4kV overhead lines, non-electrified railroads, overhead communication lines, highways, heating lines, gas pipelines, electrical cables, water line, sewage system, underground communication lines.

Due time supply of necessary materials for work performance, including all required incoming control and step-by-step inspection. was ensured during work execution,

In course of construction activities our company performed all set of commissioning works required for the сcommissioning of 110, 35 kV overhead lines, including the provision of as-built documentation. Construction design supervision was also performed by our company.

Upon the completion of 110 and 35 kV overhead lines erection, the areas used for construction were restored to the initial condition, the site improvement and landscaping were performed.

In course of construction and installation works at the facility we implemented efficient methods, contributing to cost and labor reduction, reduction of facilities construction period, increase of construction machinery and equipment involvement, Improvement of construction and installation works quality and ensuring safe work performance.

Special features and methods of work performance under the project:

1. During the preparation of Method Statement, significant amendments were made in the procedure and method of work performance, developed in construction management plan approved by the Client.
   Thus, the elaborated Method Statement additionally includes:
   1. Work performance considering time limits in regards to permit to work at the reconstructed overhead line, specifically periodic overhead line tripping and enabling due to the impossibility for the Client to ensure overhead line disconnection for the whole period of construction and installation works, as earlier stipulated in construction management plan; 
   2. Temporary use of the 3239m overhead line during work performance, to ensure electric power supply to consumers to avoid temporary “windows” at this section from the Client side.
2. In course of work performance, the Client was offered to change the previously designed location of supports in approximately 50% of cases. The Client accepted the proposal, which allowed to improve work performance conditions for set of crossings with external utilities and facilities, as well as completely exclude removal of power cables from construction area. All the required calculations of erection wire dip and check of capability to use foundation for support were performed by the company own resources.
3. In comparison with the design solution, multisided steel shell piles were used as foundation for multisided supports at three-circuit section of overhead line, instead of bore piling foundation with pile capping. Client approval was received. It allowed to avoid earthworks with sheet piling installations for foundation, reduce the cost of materials for foundation and reduce these activities work performance period.
4. The availability of qualified engineering and technical personnel allowed, using the company own resources, without involving third parties, to eliminate errors in design documentation, that were revealed during work performance, from the elaboration of design documentation up to construction and installation work performance.
5. To ensure time reduction for the engineering preparation for work performance, connected with the necessity to receive approvals of third parties, in the form of technical assistance to the Client, our company filled in the required documents and guided the approval procedures until the receipt of necessary favorable decisions.