REACTIVE SOIL Issues and solutions related to plumbing and drainage installed in reactive soils areas WWW.PLASTEC.COM.AU

LET’S DISCUSS... What is “Reactive Soil”? Issues caused by reactive soils. Legislative requirements for designers and practitioners. Product solutions for installing plumbing and drainage in reactive soil areas.

WHAT IS “REACTIVE SOIL”? Soils that are prone to expansion and contraction due to variations of moisture content. Reactive soils undergo volume change with moisture change. Many external circumstances can contribute to the movement of soil. Most common are: - atmospheric changes (droughts, wet periods) - vegetation - drainage issues - climate zone

WHAT IS “REACTIVE SOIL”? CONTINUED... Different types of soils, in particular clay and black soils, are most susceptible to movement as environmental factors change. The forces associated with reactive soils can be huge, and consequential heave can leave underground pipe work broken.

WHAT IS “REACTIVE SOIL”? CONTINUED... In severe cases the damage to the structure of a property may be visible. Some of the tell-tale signs may include: - cracked brickwork - splits in concrete paths - doors not closing

WHERE IN AUSTRALIA ARE REACTIVE SOILS?

AS2870 – CLASSIFICATION OF SOILS CONDITIONS MOVEMENT A Sand and Rock Sites 0mm S Slightly Reactive Soil 0-20mm M Moderately Reactive Soil 20-40mm H1 Highly Reactive Soil 40-60mm H2 Very Highly Reactive 60-75mm E Extremely Reactive Soil 75mm Plus P Problem Site ?

ASSOCIATED PROBLEMS PVC-U drainage solvent cemented systems are rigid and offer very little flexibility. If movement exceeds 30mm extreme stress will be placed on the system, often resulting in cracked or sheared junctions and bends. This causes fluids to leak into the sub-soil which only exacerbates the problem.

ASSOCIATED PROBLEMS CONTINUED... The action of reactive soil is tons of unrelenting, silent and slow moving pressure. For example: A standard on slab, brick house with tile roof has an average downward pressure of 25kpa per sq.mtr… Reactive soils can have an approx. upward pressure of between 400-600kpa

SLAB HEAVE – HOW IT WORKS?

SHRINK VS SWELL – AN UNNATURAL TUG OF WAR

WHAT DOES AS3500 SAY ABOUT REACTIVE SOILS? AS/NZS3500.2 Sanitary Plumbing and Drainage Amendment No. 3 Drains in other than stable ground Prior to the commencement of work, ground conditions shall be assessed by a suitably qualified person. Where ground conditions may affect the performance of any plumbing or drainage installation, the method to protect the installation shall be determined by a suitably qualified expert. Soil classification shall be in accordance with AS2870. Plumbing installation requirements shall be carried out in accordance with AS2870.

AS2870 – RESIDENTIAL SLABS AND FOOTINGS 5.6.4 Plumbing Requirements for M, H1, H2 and E Class Sites Penetrations of the edge beams of a raft and perimeter strip footings shall be avoided where practicable, but where necessary, shall be detailed to allow for movement. Closed call polyethylene lagging shall be used around all stormwater and sanitary plumbing drain pipe penetrations through footings. The lagging shall be a minimum of 20mm thick on Class H1 sites and 40mm thick on Class H2 and Class E sites. Vertical penetrations do not require lagging. On-site wastewater treatment units and associated land application areas shall be located to minimize soil moisture increase within the foundation.

Drainage under the slab shall be avoided where practicable. AS2870 – RESIDENTIAL SLABS AND FOOTINGS CONTINUED... 5.6.4 Plumbing Requirements for M, H1, H2 and E Class Sites Drainage under the slab shall be avoided where practicable. Pipes may be encased in concrete or in recesses in the slab when provided with flexible joints at the exterior of the slab. Cold and hot water pipes shall not be installed under a slab, unless the pipes are installed within a conduit so that if the pipe leaks water will be noticed above the slab or outside the slab and will not leak unnoticed under the slab.

AS2870 – RESIDENTIAL SLABS AND FOOTINGS CONTINUED... 5.6.4 Plumbing Requirements for M, H1, H2 and E Class Sites Drains attached to or emerging from underneath the building shall incorporate flexible joints immediately outside the footing and commencing within 1m of the building perimeter to accommodate a total range of differential movement in any direction equal to the estimated characteristic surface movement of the site. In the absence of specific design guidance, the fittings or other devices that are provided to allow for movement shall be set at the mid position of their range of possible movement at the time of installation, so as to allow for movement equal to 0.5ys in any direction from the initial setting. This requirement applies to all stormwater and sanitary plumbing drains and discharge pipe.

AS2870 – RESIDENTIAL SLABS AND FOOTINGS CONTINUED... 5.6.3 Plumbing Requirements for M, H1, H2 and E Class Sites Surface drainage shall be considered in the design of the footing system and necessary modification shall be included in the design documentation. Surface drainage of the site shall be controlled from the start of site preparation and construction. The drainage system shall be completed by the finish of construction of the building.

AS2870 – RESIDENTIAL SLABS AND FOOTINGS CONTINUED... 5.6.3 Plumbing Requirements for M, H1, H2 and E Class Sites The base of trenches shall be sloped away from the building. Trenches shall be backfilled with clay in the top 300mm within 1.5m of the building. The clay used for backfilling shall be compacted. Where pipes pass under the footing system, the trench shall be backfilled full depth with clay or concrete to restrict the ingress of water beneath the footing system. Subsurface drains to remove groundwater shall not be used within 1.5m of the building unless designed in accordance with engineering principles.

AS2870 – RESIDENTIAL SLABS AND FOOTINGS CONTINUED... 5.6.3 Plumbing Requirements for M, H1, H2 and E Class Sites “Where pipes pass under the footing system, the trench shall be backfilled full depth with clay to act as a barrier to the ingress of water beneath the footing system.” “Alternatively, a plastic membrane across the cross-section of the trench, taped to the pipe and keyed into the sides and base of the trench may be used.”

AUSTRALIAN TECHNICAL SPECIFICATIONS ATS 5200.055 Technical specifications for plumbing and drainage products. Part 055: Plastic fittings – Connectors with flexible intermediate joints for drainage and sewerage applications. 4.1 Expander Joint – A joint design that allows movement in a lateral plane and includes a positive stop. 4.2 Swivel Joint – A joint design that allows movement in a rotating plane and includes a positive stop.

Performance requirements and test methods: Joint Strength Test AUSTRALIAN TECHNICAL STANDARDS ATS 5200.055 CONTINUED... Performance requirements and test methods: Joint Strength Test Shear Strength Test Elastomeric Joint – Contact width and pressure Hydrostatic Pressure Test Liquid Infiltration Test High Temperature Stress-Relief Test

EXPANSION (EXPANDER) JOINT Total expansion 150mm. Available in 90mm, 100mm and 150mm sizes. Can be used horizontally or vertically. Suitable for use on wet systems with up to 8m of head pressure. Great for repairing broken pipe work.

SWIVEL (KNUCKLE) JOINT Available in FxF and MxF. 40 degrees inclusive rotation. Available in 100mm and 150mm sizes.

SWIVEL & EXPANSION COMBINATION JOINT Available in MxM, FxF, FxM and MxF . Total expansion 57mm. 40 degrees inclusive rotation. Perfect “first fitting from the footing”, as per AS2870 (5.6.4b). Ideal for in ground tank installations. Available in 100, 65 and 50mm.

INSTALLATION EXAMPLES BSA requirement. 15 degrees bend prior to swivel joint. Two combination joints piggy backed from footing on E class site.

HDPE 110 COMBO JOINT – SWIVEL & EXPANSION Can be electrofused or butt welded. Total expansion 60mm. 40 degrees inclusive rotation. Perfect “first fitting from the footing”. As per AS2870 (5.6.4b). Ideal for in ground tank and grease trap installations. Also available HDPE 110mm Expansion Joint with 150mm total expansion.

INSTALLATION EXAMPLES – HDPE COMBO JOINT

MAJOR PIPE REPAIR – NEW HOME 18 MONTHS OLD

EXPANSION JOINTS INSTALLED ON A WET SYSTEM

FLEXIBLE CONNECTIONS ON A FLOATING SLAB

WRAPPING OF FLEXIBLE CONNECTIONS

REMEMBER, FOR ALL M, H1, H2 & E CLASS SITES... …first fitting from the footing should be flexible.

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