An industrial park outside Dammam needed a complete gravity drainage network before the first factory could open. The site is flat, the groundwater is saline, and summer surface temperatures on exposed pipe can exceed 50 °C — conditions that rule out thin-wall alternatives and punish poor installation practice.
Site conditions
The 240-hectare park sits on sabkha ground: fine sand, evaporite crust, and groundwater with chloride content high enough to attack ordinary metal fittings within a few years. Design consultant required a fully non-metallic, corrosion-immune system with a design life of 50 years and a maintenance regime that assumed no internal inspection for the first decade.
Scope of supply
- DN630 and DN400 PVC-U SN8 trunk sewers, DN315 to DN160 SN4 branch collectors
- DN110 building connections, plus 1,400 inspection chambers with EPDM seals
- Solvent-cement jointing kits matched to ambient temperature, and rubber-ring couplings for the sections exposed to thermal movement
- Transition fittings to HDPE rising mains at each lift station
Installation notes
Two decisions mattered. First, bedding: instead of the usual sand envelope, the contractor used a graded gravel bed with geotextile separation, because wind-blown fines would otherwise migrate into the trench and block the invert. Second, storage: pipe was kept on timber skids under shade net, never stacked more than three high, and jointing was scheduled for early morning — PVC solvent cement behaves very differently at 45 °C than at 25 °C, and crews were given a simple rule: no cement work after 11 a.m.
Every line was flushed and ball-tested section by section before backfill. Laser levels were checked against a survey benchmark at each manhole rather than trusting the previous manhole, which caught a 40 mm grade error on the longest run before it became a problem.
Result
The network was handed over on schedule and has operated for two rainy seasons without a single joint failure. Chloride attack, the original concern, has not appeared. The client's maintenance team reports that the only interventions have been chamber cleaning, which was the design assumption from the start.
