BUILDING OVER OR NEAR WATER & SEWER MAINS POLICY

MURRAY SHIRE COUNCIL BUILDING OVER OR NEAR WATER & SEWER MAINS POLICY ADOPTED: 1 May 2012 1

BUILDING OVER OR NEAR WATER AND SEWER MAINS POLICY CONTENTS 1. Objective... 2 2. Requirements for Building Near Gravity Sewer Mains... 2 3. Considering Plans for Approval for Building Near Gravity Sewer Mains... 3 3.1 Horizontal Clearance... 3 3.2 Manholes, Lamp Holes and Rodding... 3 3.3 Deviations and Adjustments... 3 3.4 Foundation Details of the Proposed Buildings... 3 3.5 Condition Details... 4 3.6 Indemnities... 4 3.7 Zone of Influence... 4 3.8 Concrete Encasement... 4 3.9 Supervision... 5 4. Requirements for Low Pressure Sewer Mains... 5 5. Requirements for Building Near Water Mains and Sewer Rising Mains... 6 6. Enquiries... 7 7. Documentation Required... 7 APPENDIX A : Piering of Foundations Adjacent to Council s Sewer... 9 APPENDIX B : Indemnity (Sample)... 10 Page 1 of 10

1. OBJECTIVE is responsible for the operation and maintenance of the reticulated water and sewerage systems. Council has the power to enter private property and construct and maintain sewers irrespective of protective easements being placed on titles. Parties working on public and private property have an obligation to protect such sewers from accidental damage and Council may recover costs of repair. Deliberate damage or unauthorised interference with water and sewer infrastructure is an offence under the Local Government Act, 1993. The purpose of this Policy is to ensure that property owners exercise certain precautions when proposing to build adjacent to Council s water and sewer assets. These precautions are necessary to negate or reduce, as far as possible, the need for future maintenance on water and sewer assets that have buildings in their vicinity. 2. REQUIREMENTS FOR BUILDING NEAR GRAVITY SEWER MAINS 2.1 will not permit building over Council s sewer mains. 2.2 Building over sewer rising mains is not permitted. 2.3 Building over a sewer manhole/junction or within 1.5m radius of a manhole/junction is not permitted. 2.4 When building close to, but not actually over a sewer, the footings must be taken below the zone of influence relative to the trench which would be required for access to the sewer. Concrete encasement of the sewer is required in accordance with Appendix A. 2.5 Where it is proposed to construct a building across the whole frontage of a block of land which has a sewer manhole at the rear of the site, in cases where the building is not within the zone of influence of the sewer and where access to the manhole would then be denied or be through other private property, the building plan should be endorsed with special conditions as regards future access. 2.6 When building plans provide for the reduction of soil cover over a sewer to below the permissible minimum, the sewer must be encased in concrete or diverted at the owner s expense. 2.7 Rebuilding of any premises is subject to the same conditions as would be imposed in respect of an entirely new building. 2.8 Council will not permit buildings/structures to be erected over and/or within any easement and this shall include any overhang (ie. eaves, verandahs, decks or similar) of such buildings/structure. Page 2 of 10

3. CONSIDERING PLANS FOR APPROVAL FOR BUILDING NEAR GRAVITYSEWER MAINS The principles set out in Section 2 above are to be observed when considering any building proposal which is likely to affect Council s gravity sewer system. The principles could be summarised as follows: Council s sewers are to remain readily accessible to allow repair and/or renewal works to be carried out by Council in the future without undue restrictions being caused by the proposed building. No building loads are to be transmitted to Council s sewers by the proposed building; and the building is to be founded so that Council s works could be carried out without affecting the stability of the building. Wherever access to the sewer is to be restricted by building adjacent to the sewer, the sewer is to be upgraded (ie. encased in concrete) to eliminate or minimise the need for future access. These principles require the following aspects to be considered in detail: 3.1. Horizontal Clearance For open trench access where no shoring is required, ie. the trench is less than 1.5metres deep, the face of any foundations should be at least 1200mm clear of the centre line of small (up to 225mm diameter) pipes or minimum 1200mm clear of the outside of larger sewers. 3.2. Manholes, Lamp Holes and Rodding (a) No building, wall or other improvement will be permitted over or within 2metre radius of a manhole or within 0.75metre radius of a lamp hole or rodding point. (b) Unrestricted access to all manhole, lamp holes and rodding points is to be provided for working space, extending a minimum 1.2metres horizontally from the manhole or 0.75metres horizontally from the lamp hole or rodding point. (c) A minimum headroom of 2.4metres over the manhole, lamp hole or rodding point is to be provided for working space, extending a minimum 2metres horizontally from the manhole or 0.75metres horizontally from the lamp hole or rodding point. (d) Where the building extends across the whole frontage of the building block, care should be taken to ensure that access to the manhole, lamp hole or rodding point at the rear of the building is available at all times. Access from adjoining properties, unless public reserves, can only be relied on if an easement leads to the subject property to provide permanent access. Otherwise a corridor, minimum 1.8metres wide and 2.4metres high, should be provided on the ground level for access purposes. 3.3. Deviations and Adjustments If the proposed building design does not satisfy Council s building adjacent to sewer requirements, adjustment or deviation of Council s service, at the applicant s cost, may be considered. 3.4. Foundation Details of the Proposed Buildings (a) The building and its foundations are to be designed in such a way that no building loads are transmitted to Council s sewer and the pipe can be repaired or renewed at any time without affecting the stability of the building. Page 3 of 10

(b) (c) (d) Footings, piers and other foundations in the immediate vicinity of Council s sewer are to be founded at or below the invert level of the pipe, or on solid rock. All other foundations are to be located so that the building is founded below the Zone of Influence of Council s sewer trench (see section 4.8). Where building construction involves displacement piles, the application is to be referred to Council s Director of Engineering Services. No displacement piles will be permitted within 5metres of Council s sewer. Piles adjacent to the sewer need to be cored below the invert level to prevent heaving of the ground affecting the sewer. Engineers design details are required to show the design of footings and specified clearances. 3.5. Condition Details Council s requirements will be given by listing them with the Conditions of Approval. 3.6. Indemnities Council will not accept any responsibility for the design and/or execution of the construction of the proposed building near Council s sewer. In order to make this quite clear to the applicant, an Indemnity is to be signed by the property owner in all cases where a structure is built within the zone of influence of a sewer main. The Indemnity is not to replace the need of taking usual precautions. Where approved, the Indemnity may include an undertaking to remove the structure (as in cases of removable structures like above ground swimming pools, etc), or an undertaking not to make Council responsible for restoration of special surfaces (tennis courts, etc). A sample of an Indemnity used is included at Appendix B. The terms of Council s Indemnity state that Council is not held responsible for any damage to the building apart from negligence by Council or its employees. This condition is transferred to successors in title, even if they fail to renew the original Indemnity and undertaking. 3.7 Zone of Influence (a) Factors which determine the Zone of Influence are the width of trench, depth of trench and the nature of strata. (b) The Zone of Influence is that section of the ground, both vertically and horizontally, which can be affected by excavation necessary to expose the sewer for repair or renewal. This is also the zone within which building loads could be transmitted to the sewer. (c) The boundary of the Zone of Influence coincides with the angle of repose of the strata encountered. Common practice shows that the angle of repose in soil and clay is 1 horizontal to 1 vertical. The angle of response in sand, filled ground, loam, etc is 2 horizontal to 1 vertical. This boundary shall commence at the bottom corner of the trench nearest the proposed foundation. (d) The above foundation requirements shall not be used for water charged strata. Foundations in water charged ground are required to be designed by a consulting engineer and approved by Council s Director of Engineering Services. 3.8 Concrete Encasement (a) Only UPVC pipes may be encased in concrete. Permission may be given to replace other types of pipes with UPVC pipes prior to encasement. Page 4 of 10

(b) (c) (d) (e) (f) All flexible pipe joints are to be maintained. The minimum length of the encasement will be the total length of the building proposed over the sewer, plus 1000mm on either side plus any additional length to ensure encasement finishes at a flexible joint. If site conditions require, Council s Director of Engineering Services may increase this length. If a manhole is less than 2metres from the end of encasement required in (b) above, then the encasement is to be extended up to the manhole. Concrete encasement is also required where the cover over the pipes will be reduced to below the minimum safe cover. Concrete encasement may also be required to minimise the risk of failure of pipes in locations where adequate access is not available. The builder will be required to excavate the trench in accordance with WorkCover guidelines, supply and construct any formwork required and supply and place the concrete (minimum 28-day strength of 15MPa) in accordance with relevant standards. A Council Supervisor, arranged 24 hours in advance of the inspection being required, will supervise the excavation around and under the pipes, the temporary supporting of pipes, and the placing of concrete. Backfilling of the trench with suitable material must not be commenced until at least 48 hours after placing the concrete. 3.9 Supervision (a) Building and foundation work over or adjacent to a sewer, as approved by Council and encasing of the sewer, are to be carried out in the presence and to the satisfaction of a Council officer. (b) Supervision by a Council officer is required in all cases where any precaution, ie. clearances and/or special foundations, are to be observed. (c) Standard inspection fees will apply as per Council s current Community Strategic Plan. 4. REQUIREMENTS FOR LOW PRESSURE SEWER MAINS Note: Council will not permit permanent structures to be erected over or within 1.5metres of a low pressure sewer main or a valve pit. Council will allow lightweight structures such as fences, carports and pergolas over low-pressure sewer mains and valve pits, subject to the following requirements: Erection of fences over or near low-pressure sewer main and pits A brick or masonry fence erected over or within 1.5metres of a low-pressure sewer must have pier and beam foundations to the depth of the sewer invert. Posts for timber or metal fences must be located no closer than 500mm to a low pressure sewer main or valve pit. Construction of carports and pergola s over low-pressure valve pits Access to the valve pit must be available at all times. No carport or pergola support posts are permitted within 1metre of the edge of a valve pit. There must be vertical clearance of at least 3metres above the valve pit to the underside roof of a carport or pergola. Page 5 of 10

5. REQUIREMENTS FOR BUILDING NEAR WATER MAINS AND SEWER RISING MAINS Water and sewer rising mains are pressure or pumped mains. Water mains carry water which is under pressure created by mechanical pumps, or by static head (the difference in height from the water reservoir to your property). Sewer rising mains carry sewage collected at sewer pumping stations, which is then mechanically pumped to treatment plants for processing. Generally, water main and sewer rising mains on private property are located within easements, which protect the mains and permit Council continued access to the pipelines. However, Council has water mains and sewer rising mains that are not within easements. Applications to build adjacent to mains without easements will be assessed on an individual basis. If you wish to build near a water main or sewer rising main, Council approval will be subject to certain conditions, which will depend on factors such as the size of the main, the existence of an easement, the depth of the main, site access and water flow path. 5.1 Building Near Water Mains and Sewer Rising Mains (a) Unless known, the water main or sewer rising main shall have an assumed depth of 1.5metres. (b) Council may impose additional approval conditions where a proposed development limits or restricts Council s opportunity to operate and maintain a water main or sewer rising main. (c) Structures erected adjacent to a water main or sewer rising main must be self supporting within the Zone of Influence. This is generally achieved by using foundation support such as piers or piles founded to a depth which is below the Zone of Influence. The plans for the foundations must have written certification from the designing engineer that the structure is self-supporting within the Zone of Influence. The following additional conditions apply to development adjacent to a water main or sewer rising main within an easement: (d) No structures are permitted within an easement for water or sewer. Council must have unrestricted access to the easement to repair, maintain or renew the main as required. (e) No structures may overhang or project into an easement. Work carried out on mains will often involve large earthmoving machinery and trucks. (f) No earthworks or improvements are permitted within an easement without approval from Council. This includes cutting, filling, landscaping, tree planting, retaining walls, etc. The following additional conditions apply to development adjacent to a water main or sewer rising main which is not within an easement: (g) Where Council has a water main which is not within an easement, a minimum of 3metres horizontal clearance is required between the water main and any proposed structure and may be increased, where necessary, to protect the water main. (h) No earthworks or improvements are permitted within 3metres of a main without approval from Council. This includes cutting, filling, landscaping, tree planting, retaining walls, etc. The minimum horizontal clearance may be increased, where necessary, to protect the water main. Page 6 of 10

5.2 Water Main or Sewer Rising Main and the Zone of Influence A Zone of Influence exists adjacent to all Council mains. Any structures within the Zone of Influence must be designed and certified to be self-supporting. However, Council reserves the right to individually assess requirements for the Zone of Influence in relation to water mains for each development. Factors influencing the requirements may include the existence of an easement, location of a main within an easement, the size of a main, the depth of a main, access to the site and water flow paths. Generally, where Council has a water main or sewer rising main within a designated easement, the Zone of Influence is defined as extending from the easement boundary at an assumed depth of 1.5metres, upwards to the ground surface at a slope appropriate for the soil type. The assumed depth of 1.5m is to be used only where the actual pipe depth is unknown. Note: Requirements will be assessed and advised during the normal Development Application approval process. 6. ENQUIRIES The point at which Council approves or refuses to approve building plans is when those plans are submitted. Anything said by Council s officers prior to submission of plans, or any other information provided to an intending applicant, can only be of a general preliminary nature and does not constitute approval. Moreover, the accuracy with which such information can be given is necessarily dependent on the accuracy of the information supplied by the intending applicant. Building plans should set out the manner of construction, the type of material to be used and the precise location of the structure in relation to Council s asset and other structures, boundaries, etc. These factors can influence the Council s building over water or sewer main requirements and enable Council to determine the proposed location of the structure in relation to any Council asset. It is only at the building plan stage that final details can be given to the likely effects of structures on Council s assets. 7. DOCUMENTATION REQUIRED After the foundation and access requirements are advised, and before building plans will be approved by Council, the following plans must be submitted to Council s Director of Engineering Services: Two (2) Copies of Architectural Plans One (1) copy will be retained by Council. These plans must include the location of the existing asset with respect to the lot boundaries and the proposed structure(s). All dimensions indicated on the plan should be established by site survey and not copied from Council s records. If required, arrangements can be made with Council s Technical Staff or one of Council s Engineering Staff to meet on site to mark out the location of the asset. Page 7 of 10

Two (2) Copies of Foundation Structural Plans One (1) copy will be retained by Council. The plans must clearly indicate any concrete encasement of the sewer, compliance with foundation and access requirements and access to any manholes. Any other conditions indicated by Council will need to be shown. At the completion of the approved works, the applicant must submit two (2) copies of Works as Executed plans prior to final approval. DOCUMENT CONTROL Version No. Details Date Resolution No. 1 Initial Issue 1 May 2012 PD58 2 Review 3 June 2014 214 Council reserves the right to review, vary or revoke this policy at any time This Policy is scheduled for review in June 2016 Page 8 of 10

APPENDIX A Piering of Foundations Adjacent to Council s Sewer Typical Details for UPVC Pipes Page 9 of 10

APPENDIX B Indemnity (Sample) Owner s Name/Address.... Date The General Manager PO Box 21 MATHOURA NSW 2710 Dear Sir Subject Property:. RE: BUILDING ADJACENT TO WATER/SEWER MAINS INDEMNITY I/We being the owners, for the time being, of the abovementioned property, hereby agree to indemnify against all claims arising out of the presence on the subject property of the water/sewer/ mains and maintenance thereon which may result from the erection of the. adjacent to the said water/sewer mains and which do not result from negligence on the part of the Council or its officers or workmen. I/We also undertake to obtain a like indemnity from my/our successors in Title. Owner Signature Print Name.. Witness Signature Print Name.. Page 10 of 10