From Ministry of Water DCOM Manual

1 miscellaneous building works

1.1 Scope

This specification covers the general requirements for, but is not limited to, sundry items, finish hardware, sanitary installation, fire protection and disinfection.

1.2 Sundry items

1.2.1 Drying and Cleaning

Upon completion, the Contractor shall thoroughly brush and wipe down to remove dust, etc., and clean the finishing works so that they are left in a condition to the satisfaction of the Engineer.

1.2.2 Fixing to Structures. Brick and Concrete Etc.

Where fixings to structures previously constructed are to be made by setting a bolt system into preformed holes, such fixings shall be made either by rawlbolting or by using an approved proprietary resin anchor system. Where thin sections are involved or where stresses are likely to be set up which might cause damage to the structure, the use of the resin anchor system only will be permitted. Only in special circumstances will the Engineer permit rag bolts to be used. Where connections are to be by "casting-in" techniques, the "cementing-in" sockets used with the rawlbolt system or other approved bolt systems shall be accurately set to template prior to placing the surrounding concrete and shall be kept rigidly in place until the concrete has properly set. Where resin anchorage is used the Contractor shall ensure that the setting time of the resin is appropriate to the requirements for setting up, plumbing and aligning the work before it sets. Bolts shall be set to template and hole diameters shall conform to the recommendations of the suppliers. Whatever system is used, all bolts shall be cadmium plated. Where aluminium and steel are combined in any fixing system all mating surfaces shall be treated with a zinc-chromate based jointing compound prior to connecting.

1.2.3 Metal Windows, Louvres and Doors

Metal windows and doors shall be handled with care and until fixed shall be stacked on edge on clean surfaces. In brick openings, frames shall be fitted with fixing lugs in adequate number, and bedded in mortar. In concrete openings, frames shall be plugged to the walls using zinc-coated screws. To avoid corrosion of aluminium alloy frames, screws and other metal fixing in contact with them shall be of aluminium, zinc or cadmium plated. In no circum¬stances shall copper fixings be used. Frames shall not be used as centring for brickwork or to support a lintel. Frames shall be carefully pointed in 1:3 cement mortar and, after raking out the gap, shall be pointed with mastic.

1.2.4 Kind of Windows and Doors

When not otherwise specified, the Contractor shall use aluminium windows which shall be robust and of good quality. Extruded aluminium members shall be fabricated conforming to DIN 1784. Where members are formed from sheet materials they shall be fabricated conforming to DIN 1783. The main elements of the aluminium solid section out frame shall be at minimum tolerance not less than 2.0 mm thick. The thickness of all other structural elements of the sections shall be at minimum tolerance not less than 1.2 mm except for weather-stripping retaining flanges and glazing beads which may be thinner. All aluminium alloy parts shall be finished satin matt and anodized in accordance with DIN 4113. Weather-stripping shall:
• be made from materials known to be compatible with aluminium;
• not shrink or warp or adhere to sliding surfaces or closing surfaces;
• not promote corrosion when in contact with the aluminium alloy used; and,
• be resistant to deterioration by weathering.
Joints in frames shall be made neatly and accurately either by welding or by mechanical means (e.g. cleating and screwing) and may have flush, stepped or lapped surfaces. Welded joints shall be cleaned of f smooth on the surfaces which are exposed when the window or door is in the closed position or where they come into contact with glazing. Hinges and pivots shall be either of suitable corrosion-resistant materials or, if not compatible with aluminium, shall be separated from the aluminium by materials which are compatible with it. Hardware, including fixings, shall be of suitable corrosion-resistant materials. Materials or finishes which are not compatible with aluminium shall not be used unless they are satisfactorily separated from the aluminium by materials which are compatible with it. Glazing beds, gaskets, glass adaptors and glazing compound shall be of materials compatible with aluminium and finishes thereon. Windows and doors shall be such that glazing and reglazing on site is possible without the need to remove the outer frames from the structure of the building. Mosquito screens shall be fitted to all windows and external doors.

1.3 Finish Hardware

1.3.1 General

The Contractor shall furnish and install all finish hardware to complete the work as specified. The Contractor shall submit samples of all hardware to the Engineer for approval. All hardware shall have the required screws, bolts and fastenings necessary for proper installation, wrapped in paper and packed in the same package as the hardware. Each package shall be legibly labelled, indicating that portion of the work for which it is intended. All hardware shall be of the best grade, entirely free from imperfections in manufacture and finish. Quantities, weight and sizes specified herein are the minimum that will be acceptable. Finish of all hardware shall be dull stainless steel unless otherwise noted.

1.3.2 Hardware Description

1) Tabular cylinder locks: stainless finish
2) Entry, exit and office doors: keyed on side, button opposite side
Passage doors knobs both sides, no lock
Storage room:single knob with key
Toilet room:stainless outside, chrome inside, pin opening outside for emergency with button inside.
All keyed locks to be master keys for same building.
All locks to have two keys each.
Door closers:heavy duty type with stainless cover; top installation for either right or left hand operation
Stops: floor or wall mounted type, stainless
Upon completion of the hardware installation, all items shall be inspected for proper operation. All work shall be protected and any damage or incorrectness shall be repaired. Hardware shall not be fitted until the latest time in the Contract.

1.4 Sanitary Installation

1.4.1 Connections to Equipment and Fixtures

The Contractor shall provide all equipment and necessary material and labour to fixtures connect to the plumbing system all fixtures and equipment having plumbing connections, which are specified elsewhere. All connections to the sanitary drainage system shall be trapped. The supply line to each item of equipment or fixture shall be equipped with a cut-off valve to enable isolation of the item for repair and maintenance without interfering with operation of other equipment or fixtures.

1.4.2 Cutting and Repairing

The work shall be carefully laid out in advance, and no excessive cutting of construction will be permitted. Damage to buildings, piping, wiring, equipment or appurtenances as a result of cutting for installation shall be repaired by persons skilled in the trade involved.

1.4.3 Protection to Fixtures and Equipment

Pipe openings shall be closed with fixtures and caps or plugs during installation. Fixtures and equipment shall be tightly covered and protected against dirt, water and chemical or mechanical injury. Upon completion of all work, the fixtures, materials and equipment shall be thoroughly cleaned, adjusted, and operated. Belts, pulleys, chains, gears, couplings, protecting setscrews, keys and other rotating parts shall be located so that any person in close proximity thereto shall be fully enclosed or properly guarded.

1.4.4 Sanitary. Waste Water and Vent Piping - Generally

Pipe materials shall conform to the following requirements: Polyvinyl Chloride (PVC) Pipe: Fittings on PVC pipes shall be PVC socket type and shall be installed by solvent welt method. Cast Iron Pipe: "Specifications for cast iron soil pipe and fittings (ISO R-13), spigot and socket"; the pipe shall be coal tar pitch coated. Ductile Iron Pipe: As specified elsewhere.

1.4.5 Sanitary, Waste Water and Vent Piping Installations

Horizontal waste and drain pipes shall have a minimum slope of 10 mm per meter. Vent pipes in roof spaces shall be run as close as possible to the underside of the roof without forming traps in pipes, using fittings as required. Vent and branch-vent pipes shall be so sloped and connected as to drip back to the vertical stack by gravity. Changes in pipe size on sanitary and waste water drain lines shall be made with reducing fittings. Use of bushings will not be permitted. Changes in direction shall be made by the appropriate use of 45 Y- branches, long or short-sweep 90, 45, 22½, or 11¼ bends, or by a combination of these or equivalent fittings. Sanitary tees and 90-bends or elbows may be used in drainage lines only where the direction of flow is from horizontal to vertical, except elbows may be used where the change in direction of flow is either from horizontal to vertical or from vertical to horizontal, and may be used for making necessary offsets in vertical lines. Slip joints will be permitted only in trap seals or on the inlet side of the traps. Installation of pipes and fittings shall be carried out in accordance with the manufacturer's recommendations. Mitring of joints for elbows and notching of straight runs of pipe for tees will not be permitted. Threaded joints shall have ISO/R7 pipe threads with graphite or inert filler and oil, with an approved graphite compound or with polytetrafluoroethylene tape applied to the male threads only.

1.4.6 Buried Drainage Pipes

Underground drainage pipes between buildings and manholes of drainage systems shall be 150 mm diameter of the material specified above. When passing under buildings, paths, roadways, etc., drainage piping shall be laid accurately to falls on a bed of class B 10 concrete, 15 cm thick and 30 cm wide and after laying shall be entirely encased in class B 10 concrete. Exterior piping shall be laid on a bed of class B 10 concrete 15 cm thick and 30 cm wide and shall be haunched up on both sides with class B 10 concrete. Piping fixed vertically is to be well secured to walls, etc., with approved metal holder bats at every joint, built into walls as directed. Rodding and inspection eyes are to be provided at all ends and junctions for cleaning purposes. The Contractor shall give notice in writing when drainage trenches have been excavated to their full depths and trenches shall be inspected and approved by the Engineer before concrete beds are laid. The Contractor shall give further notice in writing when concrete beds have been laid and these must also be inspected and approved by the Engineer. No drainage trenches shall be filled or drains covered up until they have been inspected, properly tested, and finally approved by the Engineer, or until the dimensions of trenches, etc., have been checked and agreed upon by the Contractor and the Engineer.

1.4.7 Flashing

Pipes passing through roofs shall be flashed using lead or copper flashing with an adjustable integral flange of adequate size to extend not less than 200 mm from the pipe in all directions and flashed into the roofing to provide a watertight seal. Sanitary vent stacks through corrugated asbestos roofing shall be installed to be watertight to the details shown, with a PVC reducing socket, copper flashing and cement mortar.

1.4.8 Traps

Each fixture and piece of equipment having an integral trap or seal, requiring connections to the sanitary drainage system shall be equipped with a trap. Each trap shall be placed as near the fixture as possible, and no fixture shall be double trapped. Traps installed on PVC pipe shall be PVC. Traps installed on lavatory wastes shall be brass recess-drainage pattern, or brass-tube type, chrome plated.

1.4.9 Floor Drains

Floor drains shall have cast iron bodies with double drainage flange, weep holes and bottom outlet. Outlet shall be inside caulked or screwed. Shower and toilet room drains shall have adjustable chrome plated brass strainers with free strainer area not less than one and one half times the connecting pipe size. Pump room, equipment room and area drains shall have anti-tilting slotted cast iron grates of not less than 150 mm diameter.

1.4.10 Downspouts and Gutters

Downspouts for roof drainage shall have a diameter not less than 100 mm and shall be fabricated of light gouge galvanized steel or PVC. All offsets and bends shall be made with 450-bends and no skewed joints or bowed down spouts will be permitted. Downspouts shall be supported with galvanized steel straps or PVC straps. Gutters shall have half round or rectangular profiles in asbestos cement, PVC, or galvanized iron. The width or diameter of gutters shall be 150 mm.

1.4.11 Water Pipe, Fittings and Connection - Generally

Water pipe within structures shall be of copper and water piping in the ground shall be either of PE or PVC. Fittings for copper tubing shall be flared brass or solder-type bronze or wrought copper. Fittings for brass pipe shall be brass. Fittings for PVC pipe shall be PVC socket type.

1.4.12 Water Pipe, Fittings and Connection

The piping shall be extended to all fixtures, outlets, and equipment. The water piping system shall be installed so as to be drained. Drainage shall be accomplished using 12 mm plugged or capped fittings at each low point, except where a drain valve or a hose tap is reasonable. Pipe shall be cut accurately to measurements established at the building by the Contractor and shall be worked into place without springing or forcing. Care shall be taken not to weaken structural portions of the building. Exposed piping shall be run parallel with the lines of the building, unless otherwise indicated. Branch pipes from service lines may be taken from top, bottom, or side of the main, using such crossover fittings as may be required by structural or installation conditions. Pipes, valves and fittings shall be kept in a sufficient distance from other work and other pipes to permit not less than 25 mm between pipes and other work. No water pipe shall be buried in floors or cast in concrete walls, unless specifically indicated or approved. Changes in pipe sizes shall be made with fittings. Use of bushings will not be permitted. Change in direction shall be made with fittings. Allowance shall be made throughout for expansion and contraction of pipe. Sufficient flexibility shall be provided on all branch runouts from mains to provide for expansion and contraction of piping. Flexibility shall be provided by installing one or more turns in the line so that the piping will spring enough to allow for expansion without straining. Joints in steel piping may be screwed or flanged. Installation of pipe and fittings shall be made in accordance with the manufacturer's recommendations. Mitring of joints for elbows and notching of straight runs of pipe for test will not be permitted. Threaded joints shall have ISO/R7 pipe threads with graphite or inert filler and oil, with an approved graphite compound, or with polytetraf luoroethylene tape applied to the male threads only. Unions shall be provided where required for disconnection.

1.4.13 Valves

Valves shall be provided for piping to equipment and fixtures. No valve shall be installed on any line with its stem below the horizontal. All valves shall be gate valves, unless otherwise specified or indicated.

1.4.14 Unions

Unions shall be installed in easily accessible locations. Gaskets for flanged unions shall be of the best quality fibre, plastic or leather. Unions shall not be concealed in walls, ceilings, or partitions.

1.4.15 Hose Taps

Hose taps shall be brass with 13 mm inlet threads, hexagon shoulder, and 20 mm hose connection, unless otherwise indicated. Hose taps installed on exterior walls of buildings shall have an integral wall flange which shall be securely anchored to the wall to prevent any strain on the supply pipe when attaching or disconnecting hose. Anchors shall use brass or bronze bolts or screws with expansion shields in the concrete or masonry wall.

1.4.16 Pipe Sleeves

Pipe passing through concrete or masonry walls or concrete floors shall be provided with pipe sleeves fitted into place at the time of construction. Sleeves shall be steel pipe. Each sleeve shall extend through its respective wall, floor or roof, and shall be cut flush, except sleeves in toilet room floors shall extend 25 mm above the finished floor. Unless otherwise indicated, sleeves shall be of such size as to provide a minimum of 6 mm all around clearance between bare pipe and sleeves. The annular space between pipe and sleeve shall be packed and caulked watertight.

1.4.17 Pipe Hangers Insert and Supports

The location of hangers and supports shall be coordinated with the structural work to assure that the structural members will support the intended load.

1.4.18 Fixture Support

Wall-hung fixtures shall be fastened to the wall by 9.5 mm through bolts where appearance of the bolts is not objectionable. Exposed bolt heads in finished areas shall be hexagonal and painted. Exposed nuts shall be chromium-plated hexagonal cap nuts. Washers shall be painted or chromium-plated to match bolt heads or nuts. For solid masonry and where through bolting is objectionable, fixtures shall be fastened with 9.5 mm machine bolt expansion shields or 9.5 mm stud-type expansion bolts. For cellular-masonry construction, where through bolting is objectionable, fixtures shall be fastened with 9.5 mm toggle bolts. Toggle bolts shall extend into the cell of the masonry unit and shall be of the gravity or spring-wing type. Lavatories mounted on pipe chases shall be installed with one or two steel backup plates as required. The backup plates shall be 3.2 mm thick, 100 mm wide and not less than the width of the fixture. Urinals mounted on pipe chases shall be installed with one or two steel backup plates as required, as specified for lavatories. Backup plates shall be suspended on the inner side of the chase by two 3.2 mm thick metal clips placed in the mortar joint. The metal clips and through bolts shall be tack-welded to each plate. The plates shall be installed horizontally and fastened to the top and bottom of the lavatory or urinal as required.

1.4.19 Type of Fixtures - Generally

Material specified herein shall be the product of manufacturers regularly engaged in the manufacture of such products. Generally, all fixtures, except water closets and urinals, shall have the water supply above the rim. Fixtures with the supply discharge below the rim shall be equipped with backflow preventers. Angle stops, straight stops, stops integral with the taps, or concealed type of lock-shield, and loose-key pattern stops for supplies shall be furnished and installed with fixtures. Where space conditions will not permit standard fittings in conjunction with the cast iron floor flange, special short-radius fittings shall be provided. Connections between earthenware fixtures and sanitary pipe shall be made absolutely gastight and watertight with a closet-setting compound or with a neoprene gasket and seal. Use of natural-rubber gaskets or putty will not be permitted for these connections. Bolts shall be not less than 6.4 mm in diameter and shall be equipped with chromium-plated nuts and washers. Fixtures with outlet flanges shall be set the proper distance from floor or wall to make a first class joint with the closet-setting compound or gasket and fixture used.

1.4.20 Fixtures

The type of fitting to be used in each location shall be in accordance with the following schedule in which the sizes given for wastes taps outlets, etc., refer to the external diameter of the fitting:
• Ball valves to cisterns of sanitary fittings shall be to DIN and of the low-pressure type.
• Taps generally shall be chrome plated easy clean deck pattern bib taps to DIN. Taps shall be 15 mm in diameter and shall have capstan heads clearly marked as appropriate with red and blue spots signifying "hot" and "cold" respectively.
• Shower fittings shall be breech pattern complete with exposed fixed chrome plated riser pipes matching clips swivel pattern shower rose and taps.
• Wash down W.C. pans shall be white vitreous china to DIN 1387 with matching traps and black solid plastic ring seats and covers to DIN complete with chrome plated bar hinges and rubber buffers. Each flushing cistern shall be white vitreous china to DIN or plastic with a capacity of 9 litres and shall be provided with a side connection reversible plastic syphon and flush pipe. The cistern shall include a ball valve with rubber cone joint and a chrome plated flushing lever and shall be supported on white plastic coated support brackets.
• - Eastern type W.C.'s shall be white vitreous china suitable for sinking into floors and provided with raised foot treads and matching traps and vents. Each suite shall be supplied with a 9 litres white vitreous china or plastic side inlet flushing cistern on white plastic coated support brackets. The cistern shall be complete with the following items:
- Plastic valveless syphon;
- Ball valve with rubber cone joint;
- Overflow;
- Chrome plated chain and plastic pull;
- 42 mm diameter stainless steel flush pipe and matching fixing clips.
• Urinals shall be white vitreous china to DIN 1390 complete with division wall hangers and supports. An automatic flushing cistern of 14 litres capacity with syphon drip tap and wall hangers shall be provided. The flush pipe shall be in stainless steel complete with matching spreaders and clips together with 35 mm diameter outlet gratings and 35 mm diameter chrome plated traps.
• Counter top lavatory basins shall be self rinsing white vitreous china supported on white plastic coated support brackets and complete with the following items:
- Overflow;
- Chrome plated chain and plug;
- 35 mm diameter chrome plated waste outlet;
- Hot and cold taps;
- 35 mm diameter chrome plated bottle trap.
• Wall laboratory basins are to be white vitreous china to DIN 1386 with minimum dimensions of 550 x 400 mm. Each basin shall be complete with the following items:
- Skirting;
- Gap overflow;
- White plastic coated support brackets;
- Hot and cold taps;
- 35 mm diameter chrome plated waste outlet;
- Chrome plated chain and plug;
- 35 mm diameter chrome plated bottle trap.
• Water coolers shall be of an approved type and manufacture. They shall be free standing models of the electrically refrigerated type with a minimum cooling capacity of 30 1/h from 250C inlet water to 100C drinking water in a room temperature of 300C. The cabinets are to be corrosion proof with the cabinet frame fasteners and bases in stainless steel. The bubbler shall have a lever handle and built in pressure regulator to deliver a smooth steady flow of water at supply pressures from 1.40 to 8.60 bars. Waste outlet shall be 35 mm diameter and supply pipes shall be 15 mm diameter. The coolers shall be fitted with chrome plated swan necked glass fillers with push down valves.
• Electric water heaters shall be of an approved pressure vessel type, comprising the electric heating element, adjustable thermostat, control pumps, complete piping connection system with combined check/pressure relieve valve in the inlet side, necessary connection cable and protection switch with fuses. The storage capacity shall be not less than 120 litres

1.4.21 Testing and Sterilization of Sanitary System - Generally

Sanitary, waste, vent and water piping shall be tested by the Contractor and approved before acceptance. Underground sanitary and waste piping shall be tested before backfilling. Equipment required for test shall be furnished by the Contractor.

1.4.22 Drainage and Venting System

Piping shall be tested with water before the fixtures are installed. After the plumbing fixtures have been set and their traps filled with water, the entire drainage and venting system shall be submitted to a final test with smoke.

1.4.23 Water Test for Drainage and Venting System

Water testing shall be applied to the drainage and venting system either in its entirety or in sections. If the entire system is tested, all openings in the pipes shall be tightly closed except the highest opening, and the system shall be filled with water to the point of overflow. If the system is tested in sections, each opening except the highest opening of the section under test shall be tightly plugged, and each section shall be filled with water and tested with at least 3 metres head of water. The water shall be kept in the system, or in. the portion under test, for at least 15 minutes before the inspection starts, the system shall then be tight at all joints.

1.4.24 Final Test

When the smoke test is employed, the smoke shall be produced by a smoke machine, and a pressure equal to 25 mm water column shall be maintained for 15 minutes before inspection starts.

1.4.25 Testing and Sterilization of Water System

When the roughing-in is completed and before fixtures are set, the entire water piping systems shall be tested at a hydrostatic pressure of not less than 10.0 kg/cm2 and proved tight at this pressure for not less than 30 minutes in order to permit inspection of all joints. Where a portion of the water piping system is to be concealed before completion, this portion shall be tested separately as specified for the entire system. If inspection or test shows defects, such defective work or material shall be replaced or repaired as necessary and inspection and tests repeated. Repairs to piping shall be made with new materials. No caulking of screwed joints or holes will be acceptable.

1.4.26 Cleaning and Adjusting

Equipment, pipes, valves, fittings, fixtures and appurtenances shall be cleaned of grease, metal cuttings, and sludge that may have accumulated from operation of the system during the test. Any stoppage, discolouration or other damage to the finish, furnishings, or parts of the building, due to the Contractor's failure to properly clean the piping system, shall be repaired by the Contractor. Flush valves and automatic control devices shall be adjusted for proper operation.

1.4.27 Disinfection

After pressure tests have been made, the entire water system shall be thoroughly flushed with water until all dirt and mud have been removed before introducing chlorinating material. The chlorinating material shall be either chlorine solution or hypochlorite. The chlorinating material shall provide a dosage of not less than 50 parts per million and shall be introduced into the system in an approved manner. The treated water shall be retained in the pipe long enough to destroy all non-spore forming bacteria. Except where a shorter period is approved, the retention time shall be at least 24 hours and shall produce not less than 10 ppm of chlorine at the extreme end of the system at the end of the retention period. All valves in the system being sterilized shall be opened and closed several times during the contact period. The system shall then be flushed with clean water until the residual chlorine is reduced to less than 1.0 ppm. During the flushing period all valves and taps shall be opened and closed several times. From several points in the system the Engineer may take samples of water in properly sterilized containers for bacterial examination. Disinfection shall be repeated until tests indicate the absence of pollution for at least 2 full days. The system will not be accepted until satisfactory bacteriological results have been obtained.

1.5 Fire Protection

Portable fire extinguishers shall be installed in all buildings at strategic positions (stair cases, corridors) in a manner that traffic will not be obstructed. As a further condition, extinguishers shall be located at easily visible and accessible locations regarding the event of a fire. Preferably dry chemical extinguishers, multipurpose type, shall be supplied. As a rule powder units containing 12 kg shall be supplied, which combine all of the extinguishing effects, and are permitted for fires of class A to C in the presence of electrical voltage up to 1,000 V. For class D fires involving combustible metals dry compound extinguishers shall be introduced. The portable fire extinguishers shall be fitted with spring headed interchangeable safety valves. Rooms and areas where voltages above 1,000 V are to be present, housing relays, control and computer units shall be equipped with portable carbon dioxide extin¬guishers in addition. Also suitable masks to prevent any injury to personnel shall be supplied. All extinguishers shall be designed for service over a period of 20 years taking the conditions at the site into account. The extinguishers must be provided as early as possible, however, at latest on commencement of the commissioning preparations. After completion of the installation, random tests of 5 % of the portable extinguishers supplied shall be performed. The necessary refills shall be provided by the Contractor. The following arrangement criteria shall be met:
• Maximum travel distance to an extinguisher:22 m
• Maximum areas to be protected per extinguisher:500 m2

1.6 Disinfection

1.6.1 General

The Contractor shall furnish all equipment, labour and materials required for disinfecting hydraulic structures, and associated pipe work. Water for disinfecting shall be clean and shall be obtained from an approved source and the Contractor shall provide all necessary piping and equipment to deliver water to the points of use. Disinfecting shall be accomplished by chlorination. Chlorine dosages will be computed by the Engineer, who will furnish the Contractor with detailed instruction for proper application of the chlorine. All chlorinating operations shall be carried out in the presence of the Engineer. The words "Hydraulic Structures" as used in this section shall be taken to mean any water-bearing or water-retaining structures.

1.6.2 Preliminary Cleansing and Flushing

Prior to disinfecting, all hydraulic structures shall be cleaned by thoroughly hosing down all surfaces with a high pressure hose and nozzle of sufficient size to deliver a minimum flow of 3 litres per second. Pipe¬lines and piping shall be thoroughly flushed out before disinfecting.

1.6.3 Disinfection General:

Testing and disinfection are two independent operations, performed one after another. Any leaks found after filling shall be repaired to the satisfaction of the Engineer. Testing shall be performed in accordance to the requirements for testing stated in the general specifications for concrete before backfill is placed around the walls. Chlorination:

A strong chlorine solution (about 200 ppm) shall be sprayed on all interior surfaces of the hydraulic structure. Following t his, the structure shall be partially filled with water to a depth of approximately 30 cm. During the filling operation, a chlorine-water mixture shall be injected by means of a solution-feed chlorinating device. The dosage applied to the water shall be sufficient to give a chlorine residual of at least 50 ppm upon completion of the partial filling operation. Precaution shall be taken to prevent the strong chlorine solution from flowing back into the lines supplying the water. After the partial filling has been completed, sufficient water shall be drained from the lower ends of the appurtenant piping to ensure filling the lines with the heavily chlorinated water. Retention Period:

Chlorinated water shall be retained in the hydraulic structure and in the appurtenant piping long enough to destroy all non-spore-forming bacteria and, in any event, for at least 24 hours. After the chlorine-treated water has been retained for the required time, the chlorine residual shall be at least 25 ppm. All valves shall be operated while the lines are filled with the heavily chlorinated water. Filling in Stages:

After the chlorine residual has been checked in accordance with subsection (b), the water level in the hydraulic structure shall be raised by one quarter (¼) of the design maximum depth, by addition of clean water at a uniform rate not to exceed 40 m3/h and then allowed to stand for not less than 24 hours. Filling operations shall be done in the presence of the Engineer and shall not be commenced until he has had an opportunity to check the structure and piping for leaks and differential settlement. The rate of filling thereafter shall not exceed 300 mm/day. Before final filling is commenced, the quantity of heavily chlorinated water remaining in the structure after filling the piping shall, in the opinion of the Engineer, be sufficient to produce a chlorine residual of between 1 and 2 ppm when reservoir is full. After the structure has been filled, the strength of the chlorinated water shall be determined by the Engineer. If the chlorine residual is less than 1 ppm, an additional dosage shall be applied to the water in the structure. If the residual is greater than 2 ppm, the structure shall be partially emptied and additional clean water added. In no case shall water be released through the drain lines prior to the end of the required retention period. Any obvious leaks which appear during filling shall be repaired before continuing.