Wet Well / Dry Well Lift Stations Installation Procedure | Technical Specification

This article is about Wet Well / Dry Well Lift Stations Installation Procedure | Technical Specification of Plumbing System as per international codes and standards.

Wet Well / Dry Well Lift Stations Installation Procedure | Technical Specification

General

1. “Lift stations that receives 1800 cubic meters per day (475,560 gallons per day) or larger flows based on daily AFR shall be of the wet well/dry well type, and shall be housed in a building.
   Note: Capacity of the pumps can be read from the construction drawings”
2. All lift stations shall have facilities for bypassing the wet wells and pumps.
3. Covers for wet wells shall be aluminum, fiberglass, or concrete. The interior surface of the concrete cover shall be lined with a nonmetallic corrosion-resistant material such as PVC, or coated with APCS-19B and exterior concrete surfaces shall be coated with APCS-1B coating system. Steel covers are not permitted.
4. Pumps handling raw wastewater (sewage) shall preceded by readily accessible bar racks with clear openings not exceeding 5 centimeters (2 inches) unless pneumatic ejectors are used or special devices are installed to protect the pumps from clogging
5. Concrete wet well shall be coated externally below grade with APCS-10 bituminous paint or better. Exterior concrete surfaces above grade shall be coated with APCS-1B coating system.
   Note:Before coating, concrete shall be sealed with a low molecular weight epoxy sealer. “
6. The interior of the concrete wet well shall be internally lined with a nonmetallic corrosion-resistant material such as PVC, or coated with APCS-19B.
   Identification: Color coding of Utility Piping

A11.01 – Outside Sewage Treatment Plants

1. All underground Sanitary Sewer Piping; Industrial drains and sewer: gravity flow or forced mains shall be identified through the manhole covers. Color coding of the Manhole covers shall be as instructed / directed by the Utilities or Operations Department which ever has the jurisdiction.
2. All above ground sanitary sewer piping; Industrial drains and sewer: gravity flow or forced mains shall have color identification band to designate the liquid being conveyed in accordance with Table 3 of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006 and the direction of normal flow shall be clearly shown at every 20 ft (6096 mm) intervals. Minimum length of color field and size of letter shall be in accordance with the table shown below:
3. All underground Utility Piping e.g. Potable Water System; Raw/Fire Combined Water System; Dedicated Fire Water System; Irrigation Water System, shall be identified through the valve boxes. Color coding shall be in accordance with Table 3 of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006 and the direction of normal flow shall be clearly shown at the upstream & downstream of the control valves. Minimum length of color field and size of letter shall be in accordance with the table shown below:
4. All above ground Utility Piping e.g. Potable Water System; Raw/Fire Combined Water System; Dedicated Fire Water System; Irrigation Water System, shall be identified through the valve boxes. Color coding shall be in accordance with Table 3 of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006 and the direction of normal flow shall be clearly shown at every 20 ft (6096 mm) intervals. Minimum length of color field and size of letter shall be in accordance with the table shown below:

A11.02 – Within Sewage Treatment Plants

All above and below ground utility piping within the sewage treatment plant shall be color coded in accordance with the requirements of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006. All sides of the Piping system shall be painted of the specified color coding. Minimum length of color field and size of letter shall be in accordance with the table shown above.

Wet Well Lift Station

1. The pumps shall be spaced to prevent vortexing cavitations when the pumps are operating.
   Note: Spacing shall be as shown on the approved shop drawings”
2. Lift stations with submersible pumps or vertical line shaft pumps shall have permanent guide rails for removing the pumps. Such guide rails shall be of type 316 stainless steel.
3. Lifting monorail beams or davit shall be provided for equipment heavier than 70 kilograms.
4. The wet well shall have a corrosion resistant access firmly affixed to the interior wet well wall. Ladder shall be rail type that meets ANSI A14.3 and made of fiberglass material or plastic coated aluminum.
5. A cage or ladder safety device shall be provided where the length of climb is less than 24 feet but the top of the ladder is at a distance greater than 24 feet above ground level, floor, or roof
   (ANSI 14.3 Para 4.1.2)
6. Ladder having a length of climb greater than 50 feet shall be provided with a cage, well, or ladder safety and shall meet the following requirements: Where cages are used:
   1-The ladder shall consists of multiple sections
   2- Each section shall be horizontally offset from adjacent sections
   3- A landing platform shall be provided at least every 50 feet within the length of climb
   Note: Where ladder safety devices are used, the length of the climb may be continues, but rest platforms shall be provided at maximum intervals of 150 feet (ANSI 14.3 Para 4.1.4)
7. The wet well shall have a minimum size of 75 mm gooseneck vent that terminates not less than 3 m above the lift station deck level.
8. Emergency pump connections shall be provided on the inlet sewer and on the force main.
9. A cage or ladder safety device shall be provided where the length of climb is greater than 24 feet but does not exceed 50 feet. (ANSI 14.3 Para 4.1.3)

Wet Well/Dry Well Lift Stations

1. Non-skid corrosion resistant stairs or ladders shall be used for access to the dry well.
2. A minimum of 12 air changes / hr is required with continuous ventilation. A capacity of 30 air changes / hr is required when ventilation is intermittent
3. Where the pump pit is below the ground surface or within an enclosure, mechanical ventilation is required which shall ventilate the dry well and the wet well independently. There shall be no interconnections between the wet well and the dry well ventilating systems
4. The dry well shall have a forced ventilation system
5. The dry well shall have an automatic sump pump with a standby pump that returns spills or wash-down water to the wet well.
6. Dampers shall not be used on exhaust or fresh air ducts.
7. The dry well deck shall have removable access covers for the removal of pumps and/or motors.
8. The wet well shall have a corrosion resistant access ladder firmly affixed to the interior wet well wall meeting the requirements stated in items , B4 ,B5 and B6 of this checklist
9. The wet well shall have a minimum size of 75 mm gooseneck vent that terminates not less than 3 m above the lift station deck level.
10. Emergency pump connections shall be provided on the inlet sewer and on the force main.

International Codes and Standard References for Wet Well / Dry Well Lift Stations Installation

1- SAES-S-010 — Sanitary Sewers, 31 December, 2002
2-GI-0151.006 — Saudi Aramco Sanitary Code (SASC), February 16, 2005
3-SAES-A-104 — Wastewater Treatment, Reuse and Disposal, 10 May 2006
4-ANSI A 14.3 — American National Standard for ladders-fixed-safety requirements, ???? Latest

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