How to use the information in this section

If a reinforced bricktank is to be tendered, the dimensions and amount of material required for building it can be selected from Tables 8-14. This information can then be written in the relevant space on the Bill of Quantities.

This is not the place to explain the entire tendering process, but this brief information will assist you in reaching an agreement with a contractor. Tender documents should be given to at least three contractors, in order to receive competitive prices. There are three different tendering documents: Conditions of Contract, Standard Specifications and Bill of Quantities After the documents have been completed by the contractors, they should be compared to ascertain the differences in prices. The cheapest contractor is not always the best, however, and workmanship demonstrated on previous projects should be taken into consideration.

Examples of the above-listed tendering documents follow.

Contract Conditions

After the tender has been accepted, an agreement shall be made and entered into by and between

(Name of Client)_____hereinafter called 'Employer' on the one part, and

(Name and address of contractor) _____hereinafter called 'Contractor' on the other part.

Whereas the Employer is desirous of the erection and completion of a rainwater reservoir as a reinforced brickwork structure, and has caused drawings of the work to be prepared, and whereas said drawing Nos.____ have been signed by or on behalf of the Employer and the Contractor, the following is hereby agreed:

1. For consideration hereinafter mentioned, the Contractor will upon and subject to the conditions annexed hereto as Standard Specifications execute and complete the works shown and described upon the said drawings, and as quoted for in the Bill of Quantities.

2. The Employer will pay the Contractor the sum of____ (hereinafter referred to as the Contract Sum) for the erection of the reinforced brickwork.

3. Date of Completion

Possession of the site shall be given to the Contractor on or before (Day, Month, Year)

____who shall thereupon and forthwith begin the works, and regularly

proceed with and complete the same on or before (Day, Month, Year) ____

4. Damage and Non-Completion

If the Contractor fails to complete the works by (Day, Month, Year)____

or within any extended time given by the Employer in writing, the Contractor shall pay or allow to the Employer as liquidated and ascertained damages the sum of_____ for every day of non-completion. The Employer may deduct such damages from any

money due to the Contractor.

5. Certificates of Payments

The Contractor shall be entitled to a Certificate of Payment on the day of commencing the construction work, not exceeding 33% of the Contract Sum. Final payment shall be due the day of completion providing proof the mentioned structure is waterproof.

Signed and deted by the Contractor_____________________________________

1. As Witness (Date______________________ Signature ___________________)

2. As Witness (Date______________________ Signature ___________________)

Signed and deted by the Employer_______________________________________

1. As Witness (Date______________________ Signature ___________________)

2. As Witness (Date______________________ Signature ___________________)

Standard Specifications for Reinforced Bricktanks

Material and Workmanship

The whole of the works shall be carried out and completed in the best and most workmanlike manner, and with the best materials of the kind respectively specified. No second-hand materials shall be used.

Protection

The Contractor shall protect all materials and work from damage during the progress of the works, until completion and handover.

Excavation

Nature of Soil

The Contractor shall base his contract sum on excavations in 'pickable' materiel. Should soft or hard rock be encountered, the contract sum shall be adjusted in accordance with the schedule of rates and measurements taken on site.

Hard Rock

When used, the term 'hard rock' means granite, quartzite or other rock of similar hardness which, in the opinion of the Clerk of Works (Site Supervisor), can only be removed by wedging, drill splitting or blasting.

Soft Rock

The term 'soft rock' is understood to mean all hard ground such as ouklip, shale, decomposed rock and small loose boulders or large stones.

Pickable Material

The term 'pickable material' is understood to mean all earth, clay, gravel, soft shale, made-up ground, etc., which can be removed by means of a pick and shovel.

Trenches/Excavations

The foundation shall not be concreted until the Clerk of Works has signified his opinion in writing that proper bottom has been obtained' and reinforcement shall not be placed until all necessary variations have been measured.

Any excavated matter taken out below the level shown as required to obtain a solid bottom shall be filled up by the Contractor with lean concrete. Measurements of the amount of lean concrete required shall be taken before backfilling begins.

Backfilling

Return and fill around foundations with selected clean, hard, dry earth from the excavation. Backfill should be watered and rammed.

Filling under the Floor Slab

Fill in under solid floor slabs with selected clean, hard, dry earth from the excavation. Water the fill and ram it in layers not exceeding a thickness of 250 mm. The fill should be consolidated and levelled as required.

Should the earth from the excavation be unsuitable or insufficient for this purpose, the Contractor is to supply the required material. No pot clay should be used for filling.

Concrete Work

Concrete work shall consist of providing, placing, curing, etc., the concrete specified in terms of 28-day strength, inclusive of all formwork.

Material Storage

All material shall be as described hereunder. Cement shall be stored in a cool, dry place and used in the order of delivery to the site. Cement which has become damp or has deteriorated in any way shall be removed from the site immediately.

Sand and stones shall be stored in separate bays and heaps, and shall not be placed with earth, grass or other impurities.

Cement

Only Portland cement of an approved brand shall be used, and shall conform to latest British standard specifications in force at the time the tender is submitted.

Stones

Stones for concrete shall be clean, hard, durable particles without soft weathering properties, and shall vary in size from a minimum which fails to pass through a mesh sieve screen of 5 mm to the maximum of 20 mm.

Sand (Concrete)

Sand for concrete shall be clean, sharp, or other approved sand. It shall be graded free from soft particles, clay, organic matter or other impurities, and washed if so directed by the Clerk of Works. Crusher sand shall not be used.

Water

Clean, fresh water from an approved source shall be used throughout. The water shall be free of vegetable or organic matter, earth, clay, acid or alkaline substances, either in suspension or in solution.

Mixing, Transport and Placing Concrete

1: 2: 1 = one part cement, two parts 20-mm aggregate, one part river sand shall be mixed in an appropriate concrete mixer at a time specified by the Clerk of Works, and shall not exceed the amount required for immediate use.

Concrete shall be transported by suitable means without causing any segregation or loss of ingredients, and shall be placed within 10 minutes of leaving the mixer. The mixture shall be plastic in consistency, and under no circumstances be of a consistency which can be poured (chuted concrete). The Contractor shall be directed when and where to use mechanical vibrators. Tamping rods or other suitable means of compacting the concrete may be adopted.

Curing

The concrete shall be covered with a layer of sacking, canvas hessian or similar absorbent material, and shall be kept wet constantly for seven days. Alternatively, when thoroughly wet, the concrete may be covered by a layer of approved waterproof material, which shall be in contact with the concrete for seven days.

Reinforcement

Unless otherwise described, mild steel rod or bar reinforcement which complies with British standards shall be used, and shall be supplied truly straight. Fabric (mesh) reinforcement shall also comply with British standards, and all fabric reinforcement shall be held in place securely by welding. Fabric reinforcement shall be supplied in flat sheets, unless approved otherwise. If fabric reinforcement is supplied in rolls' it shall be cut to the required size immediately, placed on flat ground and straightened for several days, by pressing it with a heavy weight.

Reinforcement shall be bent to the required detail, and cold-formed by approved means. Reinforcement shall be free from loose mill scale, rust, oil, grease or other harmful matter.

Unless otherwise directed, reinforcement shall be covered with the following: slab -15 mm, beam -25 mm, foundation -50 mm. Concrete covering for reinforcement shall be maintained as shown on detailed drawings, using all necessary spacers and other temporary supports as required.

Formwork

Formwork shall be approved and shall conform to the shape, lines, levels and dimensions of the concrete, as shown in the drawings, and shall be true, rigid, properly braced and sufficiently strong enough to prevent bulging or distortion. All joints shall be sufficiently tight to prevent loss of liquid from the concrete. Immediately before concreting, the area of timber in contact with the concrete shall be thoroughly wet or, preferably, treated with shutter oil. When shutter oil is used, none of it shall come into contact with the reinforcement. The Contractor shall be responsible for any damage to work and any consequent damage caused by negligent handling of formwork. Formwork for roof slab shall not be removed before permission to do so has been given by the Clerk of Works. The minimum period required before removal is 14 days, during which the slab shall be kept wet at all times, or covered with an approved waterproof material which shall be in contact with the concrete for the entire period.

Brickwork

Cement

See Concrete Work above.

Sand

Pit sand free of clay and vegetable matter shall be mixed with fine river sand to produce a workable and strong mortar. Sand for mortar shall be fine-grained and, if required, shall be screened through a 3-mm sieve screen.

Cement Mortar

Cement mortar shall be made of three parts sand to one part cement by volume. Cement mortar shall be mixed in small quantities and shall be used within 30 minutes of mixing.

Bricks

The dimensions, crushing strength and absorption of clay bricks or cement bricks shall comply with standard specifications. Before use, all bricks shall be saturated with water.

Brickwork

Brickwork shall be well bedded and flushed up solid in mortar throughout the whole wall. No one portion of the wall shall be raised more than one metre above the remaining wall. Mortar joints shall be 10 mm thick. All wall reinforcement shall be covered entirely with cement mortar joints.

Brickwork shall be built in cross bond; no false headers shall be used. Horizontal reinforcement shall be tied with binding wire on vertical rods from the inside.

Cement Screed

Cement screed shall comprise one part cement to three parts sand and shall be floated to a true plane surface with a wooden float. Sand used for screed shall be screened through a 3-mm mesh screen to expel all vegetable matter, pebbles, etc. Sand used shall be pure river sand with less than 6% clay, silt, etc. Before commencing work, the quality of the sand shall be proven by test, and submitted to the Clerk of Works. After the float-frushed screed has been watered for 24 hours, the nil coat shall be applied, using a steel trowel.

Waterproof Plaster

Three-Coat Plaster

First Coat: 10 -15 mm cement plaster of one part cement and three parts river sand screened through a 3-mm sieve screen shall be wooden-float-finished.

Second Coat: 5 -8 mm cement plaster mixture, as described in First Coat above, shall be screened through a 1.5-mm sieve screen.

Third Coat: This shall be a nil coat composed of pure cement with a consistency of water, and shall be steel-trowel-finished. The plaster shall be cured after each coat has been applied, and when the third (nil) coat has been applied, it shall be covered with waterproof material or soaked thoroughly for seven days.

Bill of Quantities

			Quantity Unit Rate Amount
Earth: Excavate oversite average 100 mm deep to remove vegetable soil, remove, and deposit according to Employer's advice, not exceeding 50 m			m²
Earth: Excavate foundation trench to 'Barth' not exceeding 0.50 m deep and remove, part-return, fill in and ram around foundation			m³
Earth: Additional excavations for trenches to reach stable ground			m³
Earth: Additional excavation for inner circle to reach stable ground			m³
Earth: Backfilling and ramming of hardcore approved material in layers not exceeding 200 mm			m³
Earth: Lean concrete for backfilling: 1 part cement: 2 parts river sand: 4 parts gravel			m³
Reinforcement: Supply and place reinforcement cage for ring foundation and welded reinforcement mesh for bottom slab consisting of
	Mild steel rods Ø 20		m²
	Mild steel rods Ø8		m
	Welded reinforcement mesh		m
Concrete: 1 :2 :1 -20-mm aggregate as specified in ring foundation and slab compacting by mechanical vibrator			m³
Reinforced Brickwork: 240-mm brick wall in cross bond reinforced vertically by 10-mm mild steel rods and horizontally by 6-mm mild steel rods
	Brick wall	m²
	Mild steel rods Ø10	m
	Mild steel rods Ø6	m
Waterproof cement plaster consisting of 3 coats as specified, inclusive curing			m²
Concrete Slab Seating: Plaster of the wall top steel-trowel-finished and placing of 2 layers plastic sheeting to provide for sliding joint under roof slab
Reinforcement of Roof Slab: Supply and place mild steel reinforcement cage for roof lintel and welded reinforcement mesh for roof slab consisting of
	Mild steel rods Ø6		m
	Mild steel rods Ø20		m
	Welded mesh		m²
Formwork and Concreting Roof Slab: Concrete 1: 2: 1 as specified compacting by mechanical vibrator			m²
Supply and place water tap unit according to drawing			1	Nº
Supply and place overflow 150 mm Øasbestos pipe of 800 mm length provided with galvanized gauze wire cover			1	Nº
Supply and place manhole cover 600/450 mm cast iron painted 3 times with bitumen-protected nontoxic paint			1	Nº
Cement floor screed 1 = 3 inclusive concave moulding of corner			m²
Lime whitewash of 1 part lime and 1 part river sand for outside elevation			m²
	Carried to Summary