Liquid Sanitation Network Extension and Pumping Stations - Mirleft Center (3rd Phase)
Execution of liquid sanitation network extension works, including the installation of HDPE pipes, the construction of reinforced concrete ancillary structures (manholes, connection boxes), and the installation of two prefabricated pumping stations equipped with backup generators in Mirleft center, Sidi Ifni Province.
- Pipelines: Double-wall HDPE/PP pipes (class CR8), DN 250 mm (20,384 ml) and DN 300 mm (3,850 ml).
- Ancillary structures: 522 simple inspection manholes, 10 drop manholes, 200 blind manholes, 850 connection boxes, septic tanks (66 + 34 m³), and soakaway pits (Ø 3m, H 8.6m).
- Pumping Stations (Kits): 2 prefabricated GRP stations with self-cleaning bottoms, equipped with 2 submersible pump sets (1 duty + 1 standby), integrated automatic screening, 50L anti-water hammer bladder, and a 25 KVA backup generator.
My role and responsibilities
-Analysis of Tender Documents (DCE) and Technical Specifications (CCTP).
-Execution studies, as-built plans, and dimensioning calculation notes (hydraulic, reinforced concrete, reinforcement).
-Site planning and organization, including the development of the Health and Safety Plan (HSP).
-Supervision of earthworks, pipe laying, and civil engineering of ancillary structures.
-Technical coordination for the supply, installation, and commissioning of hydro-mechanical and electrical equipment for the pumping stations.
Project scope
The project covers the 3rd phase of the Mirleft liquid sanitation network. It includes:
-Extension of the gravity and pressure network (discharge pipes).
-Construction of ancillary structures: manholes, drop manholes, blind manholes, and connection boxes.
-Road and track crossings (via open trench or pipe jacking).
-Supply, installation, and commissioning of two (02) prefabricated pumping stations (Kits) with technical buildings and backup generators.
Construction methods
-Earthworks: Trench opening with shoring if necessary, respecting regulatory trench widths (0.60 m to 1.20 m depending on DN). Evacuation of excess spoil and reuse of good quality soil for backfilling.
-Pipe Laying: Installation of a sand (10 cm) or gravel (15 cm) bedding depending on soil conditions. Laying of double-wall HDPE pipes, primary encasement, and secondary backfill compacted in 20 cm layers to 95% of Modified Proctor density.
-Civil Engineering: Construction of reinforced concrete manholes and connection boxes (B20/B30) with proper treatment of construction joints and waterproofing.
-Pumping Stations: Excavation, installation of Glass Reinforced Plastic (GRP) tanks, connection of 316L stainless steel piping, installation of electromechanical equipment, and generator setup.
Technical specifications
-Pipes: Double-wall HDPE or PP, stiffness class SN8 (CR8). Diameters: DN 250 mm and DN 300 mm. Nominal pressure: 10 bar for discharge lines.
-Ancillary Structures: Ductile iron D400 manhole covers (hinged and locked), composite high-strength steel steps fully encased in polymer.
-Pumping Stations (Kits 1 & 2): GRP tank with self-cleaning bottom, 2 submersible pump sets (1 duty + 1 standby), automatic stainless steel 316L screen, electromagnetic flowmeter, 50L anti-water hammer bladder tank.
-Electrical: Low voltage connection (IT neutral system), supplemented by a 25 KVA soundproof generator with an automatic transfer switch.
Key quantities
| Item | Quantity | Unit |
|---|---|---|
| Conduite PEHD double paroi CR8 DN 250 mm | 20,384 | ml |
| Conduite PEHD double paroi CR8 DN 300 mm | 3,850 | ml |
| Regards de visite simples | 522 | unité |
| Regards de chute | 10 | unité |
| Regards borgnes | 200 | unité |
| Boîtes de branchement simples | 850 | unité |
| Stations de pompage préfabriquées (Kit complet avec GE 25 KVA) | 2 | ensemble |
| Traversée de chaussée par fonçage | 1 | forfait |
| Fosse septique (Volume 66 m³ + 34 m³) | 1 | unité |
| Puits perdus (diam 3m, H 8,6m) | 1 | unité |