Ground tank cleaning — once a year (per tank)
Added to an annual package (ready, custom or institution); not sold on its own.
Draining the ground tank, removing sediment, and washing and rinsing its walls and floor, once a year.
Unit: per tank. Carried out during your scheduled annual subscription visits, with a photo report after each visit.
The engineer confirms the numbers at the first visit: any excess is charged and any shortfall refunded. The price is fixed for the subscription year.