1. SD Water supply and drainage systems Universidad de A Coruña Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos Water supply and drainage systems Hochschule Magdeburg-Stendal Fachbereich Wasser und Kreislaufwirtschaft SD 1

2. Water supply and drainage systems Index 0. Introduction (2h, Pablo Rodríguez-Vellando) 1.Water supply and drainage, a historical approach (8h, Alberte Martínez López) 2.Water provision and consumption, distribution networks (8 h, Gustavo V. Herrero) 3.Abstraction of water (4h, Jordi Delgado Martín) 4.Water supply treatment (8h, Pablo Rodríguez-Vellando) 5.Water drainage treatment (4h Héctor García Rábade + 4h Gustavo V. Herrero ) 6.Constructive aspects of water supply and drainage systems (4h, Cristina V Herrero) 7.Water law (8h, Javier Sanz Larruga) SD

3. Water supply and drainage systems 6. Constructive aspects of water supply and drainage systems 6.0 Introduction 6.1. Concrete components 6.2. Concrete mix design 6.3. Loads on water supply and drainage structures 6.4. Structural design criteria 6.5. Installation recommendations 6.6. Summary and conclusions Bibliography Annex. Glossary SD 3

4. Water supply and drainage systems 6.0. Introduction 4

5. SD Water supply and drainage systems Key concepts Practice Critical analysis Research 5

6. SD Water supply and drainage systems Objectives of these lectures The purpose of these lectures is to provide the students a general insight of the constructive aspects that should be considered to design, build and maintain water supply and drainage systems with the minimum overall cost, accounting for maximum durability of the water supply and drainage systems and with minimum environmental impact. Due to the diverse background of the students, the lectures are aimed at providing general criteria. SD i6

7. SD Water supply and drainage systems Reinforced concrete is the main material used in water supply and drainage systems, whose durability is conditioned by concrete quality. Let us study the main constructive aspects related to this material! What is concrete? Concrete is a mixture of paste and aggregates. The paste, composed of portland cement and water, coats the surface of the fine and coarse aggregates. Through chemical reactions called setting, the paste hardens and gains strength. 7

8. SD Water supply and drainage systems Within this process lies the key to a remarkable trait of concrete: it's plastic and malleable when newly mixed, strong and durable when hardened. Concrete’s ECO2 measures its environmental impact. 8

9. SD Water supply and drainage systems The problem: What design and construction criteria should be considered for maximum durability of concrete pipes and tanks? 9

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12. SD Water supply and drainage systems 12 Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

13. SD Water supply and drainage systems Factors contributing to corrosion by hydrogen sulfide generation: Retention time in sewer Velocities tha are not self-cleansing Silt accumulation Temperature Biochemical oxygen demand Dissolved oxygen in effluent Dissolved sulfides in effluent Effluent pH 13

14. SD Water supply and drainage systems Factors contributing to corrosion by hydrogen sulfide release from the effluent: Concentration of hydrogen sulfide in effluent High velocities and turbulence Factors contributing to H 2 SO 4 on the sewer walls: Concentration of H 2 S in sewer walls Rate of acid formation The aoumnt of moisture on sewer walls 14

15. SD Water supply and drainage systems 15 Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

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17. SD Water supply and drainage systems http://eurocodes.jrc.ec.europa.eu/doc/WS2008/EN1992_1_Walraven.pdf 17

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20. SD Water supply and drainage systems What are the chemical agents responsible for corrosion of concrete pipes and tanks? 20

21. SD Water supply and drainage systems 6.1. Concrete components 21

22. SD Water supply and drainage systems http://www.concretethinker.com/solutions/Stewardship.aspx 22 Cement Coarse aggregate Fine aggregate Water Air Additives Admixtures SCMs

23. SD Water supply and drainage systems http://www.cement.org/basics/concretebasics_concretebasics.asp What is concrete made of? 23

24. SD Water supply and drainage systems What are RAs? Ras accounts for recycled aggregates that come from debris 24

25. SD Water supply and drainage systems What are RCAs? RCAs accounts for recycled concrete aggregates that come from demolition of concrete 25

26. SD Water supply and drainage systems What are admixtures? Admixtures account for materials other than water, aggregates, cement and fiber reinforcement used as an ingredient of concrete and added to the batch immediately before or during its mixing. 26

27. SD Water supply and drainage systems Admixture, accelerating – an admixture that accelerates the setting and early strength development of concrete. Admixture, air-entraining – an admixture that causes the development of a system of microscopic air bubbles in concrete, mortar or cement paste during mixing. Admixture, water-reducing – admixture that either increases the slump of freshly mixed concrete without increasing the water content or that maintains the slump with a reduced amount of water. 27

28. SD Water supply and drainage systems Accelerating admixtures (ASTM C494,“Specification for Chemical Admixtures for Concrete”) Air entrainment admixtures (ASTM C260, “Specification for Air-Entraining Admixtures for Concrete”) Water reducing admixtures (ASTM C494, “Specification for Chemical Admixtures for Concrete”) High-range water-reducing admixtures or superplasticizers (ASTM C494, “Standard Specification for Chemical Admixtures for Concrete; ASTM C1017, “Chemical Admixtures for Use in Producing Flowing Concrete”) 28

29. SD Water supply and drainage systems What are SCMs? SCMs accounts for supplementary Cementitious Materials. 1. Cementitious materials – Ground Granulated blast furnace slag (ASTM C989) 2. Pozzolanic materials – Class F fly ash, silica fume, metakaolin (ASTM C618, ASTM C1240) 3. Pozzolanic and cementitious materials – Class C fly ashes (ASTM C618) 29

30. SD Water supply and drainage systems 6.2. Concrete mix design 30

31. SD Water supply and drainage systems What is concrete mix design? Concrete mix design is aimed at determining the most economical and practical combination of readily available materials to produce a concrete that will satisfy the performance requirements under particular conditions of use. Components should be provided in kg/m 3 Normal weight concrete specific weight: ρ=2000-2400 kg/m 3 31

32. SD Water supply and drainage systems Example: SCC=self-compacting concrete 32

33. SD Water supply and drainage systems What is important about concrete mix design? A compact concrete is intended, with the minimum cement paste 33 Watertight=water resistant

34. SD Water supply and drainage systems Well graded aggregate Tecnoval project, Innterconnecta-FEDER 34

35. SD Water supply and drainage systems Factors to be considered include: Workability Cohesiveness, slump Placement conditions Strength Durability Appearance Economy Minimize the amount of cement Minimize w/c ratio Minimize amount of water 35

36. SD Water supply and drainage systems Mix designs are selected based upon several necessary factors including permeability, consistency, workability, strength and durability (ACI 211). The elements necessary to achieve high-quality watertight precast concrete include: Minimum compressive strength of 4,000 psi (28 MPa) at 28 days Low water-cementitious ratio (less than 0.45) Use of good quality and properly graded aggregate Proper concrete consistency. 36

37. SD Water supply and drainage systems The following recommendations are aimed at specifying concrete with a low environmental impact (low ECO 2 ): Do not over-specify concrete strength. Consider the possibility of strength conformity at 56 days rather than the conventional 28 days, answering the question: When will be the structure put to use? Will it be after 28 days? Specify responsibly-sourced concrete and reinforcement (so as to guarantee quality and sustainable production). 37

38. SD Water supply and drainage systems Do not specify aggregate size below 10 mm unless necessary (as it demands more cement paste). Permit the use of recycled or secondary aggregates but do not over specify. Current standards allow 20% recycled aggregates. Beware of the transport distance, as it increases cost and ECO 2 ! Specify that concrete should always contain CEMII/CEMIII or an addition, as ECO2 is lower than CEMI cement’s 38

39. SD Water supply and drainage systems Permit the use of admixtures, as they reduce the embodied C02(ECO2). Beware of concrete colour and appearance! Consider the local environmental regulations, i.e. BREEAM (UK) 39

40. SD Water supply and drainage systems 40 6.2.1. Exposure class

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42. SD Water supply and drainage systems 6.2.2. Cement http://iti.northwestern.edu/cement/monograph/Monograph3_8.html 42

43. SD Water supply and drainage systems There is actually little difference between a Type I and Type II cement, and it is common to see cements meeting both designations labeled as “Type I/II”. It should be noted here that the most effective way to prevent sulfate attack is to keep the sulfate ions from entering the concrete in the first place. This can be done by using mix designs that give a low permeability (mainly by keeping the w/c ratio low) and, if practical, by putting physical barriers such as sheets of plastic between the concrete and the soil. 43

44. SD Water supply and drainage systems Types II and V OPC are designed to be resistant to sulfate attack. Sulfate attack is an important phenomenon that can cause severe damage to concrete structures. It is a chemical reaction between the hydration products of C 3 A and sulfate ions that enter the concrete from the outside environment. The products generated by this reaction have a larger volume than the reactants, and this creates stresses which force the concrete to expand and crack. Although hydration products of C 4 AF are similar to those of C 3 A, they are less vulnerable to expansion, so the designations for Type II and Type V cement focus on keeping the C 3 A content low. 44

45. SD Water supply and drainage systems Class exercise: What exposure class and what types of cement would you use? Septic tank exposure class Water supply system submerged in seawater Water supply system in aggresive soils Water drainage system in highway, cold weather, use of deicing agents 45

46. SD Water supply and drainage systems Solution: 46

47. SD Water supply and drainage systems 4.2.3. Aggregates Concrete is exposed to continuous moist and corrosive conditions in wastewater applications. It is important to specify a well-graded, sound, nonporous aggregate in accordance with ASTM C33, “Standard Specification for Concrete Aggregates.” 47

48. SD Water supply and drainage systems Ensure aggregates conform to the requirements of ASTM C33. Evaluate the aggregates and maintain documentation at the plant for potential deleterious expansion due to alkali reactivity, unless the aggregates come from a state department of transportation approved source. 48

49. SD Water supply and drainage systems The maximum size of coarse aggregate should be as large as practical, but should not exceed 20% of the minimum thickness of the precast concrete tank or 75% of the clear cover between reinforcement and the surface of the tank. Larger maximum sizes of aggregate may be used if evidence shows that satisfactory concrete products can be produced. 49

50. SD Water supply and drainage systems RA: recycled aggregates RCA: recycled concrete aggregates 50 Recycled aggregates RAs RCAs http://iti.northwestern.edu/cement/monograph/Monograph3_8.html

51. SD Water supply and drainage systems 6.3. Loads on water supply and drainage structures 51

52. SD Water supply and drainage systems 52 t Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

53. SD Water supply and drainage systems 53 Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

54. SD Water supply and drainage systems Consider the following loads in the design: Internal water pressure Water table Self weight of structure Soil pressures Buoyancy (Archimedes effect) Loads caused by water flow Other loads 54

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56. SD Water supply and drainage systems 56 Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

57. SD Water supply and drainage systems 57 Concrete Manufacturers Association. Design manual for concrete pipe outfall sewers. April 2009

58. SD Water supply and drainage systems Class exercise: Determine possible class exposure and represent all the loads applied to the following buried tank, as a function of water table: max 58 min

59. SD Water supply and drainage systems Solution maximum water table: 59

60. SD Water supply and drainage systems Solution minimum water table: 60

61. SD Water supply and drainage systems 6.4. Structural design criteria 61

62. SD Water supply and drainage systems 6.4.1. Reinforcement Proper reinforcement is critical to withstand the loads applied to an on-site wastewater tank. Reinforcement must be sufficient to provide adequate strength during early-age handling, installation and service, including temperature and shrinkage effects. All reinforcement must meet applicable ASTM International specifications. 62

63. SD Water supply and drainage systems 6.4.2. Concrete Thickness The concrete thickness must be sufficient to meet minimum reinforcement cover requirements and withstand design loading conditions. 63

64. SD Water supply and drainage systems 64 Concrete thickness, reinforcement layout, concrete cover and corrosion protection lining

65. SD Water supply and drainage systems Recommendations (Humes, Concrete Pipes Reference Manual, January 2009): With a minimum cementitious cement content in excess of 400 kg/m 3, standard sewer pipes are adequate for most properly designed sewer systems. The cover to reinforcement can be increased to up to 25 mm An increased wall thickness can be provided at the internal diameter, as a sacrificial layer Calcium rich aggregate, such as limestone provides added resistance to acidic corrosion, thus increasing durability Corrosion protection linings provide the ultimate protection against chemical attack in a sewerage environment 65

66. SD Water supply and drainage systems 6.4.3. Concrete curing All efforts to attain quality concrete will be lost if the concrete is not properly cured. Efforts should be made to control the moisture migration from the concrete product and temperatures should be sufficient to allow hydration to occur. For concrete to be watertight, water must not be able to flow through its hardened pore structure. Low water-cementitious ratios are critical for increased concrete strength, watertightness and decreased permeability. 66

67. SD Water supply and drainage systems High water-cementitious ratios yield undesirable increased capillary porosity within the concrete. Capillary pores are voids resulting from the consumption and evaporation of water during the hydration or curing process. Enlarged and interconnected capillary voids serve as pathways that allow water and other contaminants to either infiltrate or exfiltrate through the concrete. 67

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69. SD Water supply and drainage systems The Portland Concrete Association (PCA) lists three methods of curing: 1. Maintaining water moisture by wetting (fogging, spraying, wet coverings) 2. Preventing the loss of water by sealing (plastic coverings or applying curing compounds according to ASTM C309) 3. Applying heat (often in conjunction with moisture, with heaters or live steam) 69

70. SD Water supply and drainage systems SD http://www.dot.state.mn.us/materials/manuals/concrete/Chapter2.pdf 70

71. SD Water supply and drainage systems Concrete maturity method, S=f(t,T) 71 Malhotra&Carino 04 QUALITY CONTROL Ambient & internal temp. monitoring EaEa tete S d (t)<R d (t e ) CONCRETE MIX DESIGNED & TESTED IN BATCHING PLANT

72. SD Water supply and drainage systems 6.4.4. Sealants Sealants conforming to ASTM C990, Standard Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants” typically meet the criteria listed above. 72

73. SD Water supply and drainage systems 6.4.5. Coatings A properly designed concrete mix is sufficiently watertight for on-site wastewater tanks. Under normal in-service conditions, there is no need for additional applications of asphalt, bituminous, epoxy or cementitious coatings. However, a protective coating may be specified when a soil analysis or other factors indicates a potential for chemical attack. 73

74. SD Water supply and drainage systems If a coating is required, it is important to apply properly, or it may peel away from the concrete surface and cause dislodged particles of coatings to move through the septic system and clog the drain field. 74

75. SD Water supply and drainage systems 75 6.4.5. Joints Joints ought to be watertight and resist the bending moments, shear and tensions tranmitted between the structure’s parts

76. SD Water supply and drainage systems 76 Example: What movements are allowed by these joints?

77. SD Water supply and drainage systems 6.4.6. Sealing Materials Use high-quality, preformed, flexible joint sealants to achieve a watertight seal in multiple-piece tanks: Compressibility in ambient temperatures below 5˚C Adhesion to clean, dry surfaces Resistance to degradation caused by aging (shrinkage, hardening or oxidizing) Resistance to degradation caused by exposure to sewage materials 77

78. SD Water supply and drainage systems Sealant Size A critical factor when evaluating the sealing potential of a sealant is cross-sectional area. Cross-sectional area is defined as the geometric shape of the sealant (0.75 x 1.0 [20 x 25 mm]). The sealed joint gap between two mating joint surfaces should not exceed 3/8 inch. Industry experience has shown that a sealant’s crosssectional height must be compressed a maximum of 50%. 78

79. SD Water supply and drainage systems Apply sealants to form a continuous length of seal. Properly splice the sealant by one of the following methods: Overlap splice: Place one piece on top of the other and carefully mold together Side-by-side: Place ends in a parallel position and carefully mold the two pieces together 79

80. SD Water supply and drainage systems Pipe-to-Tank Seals The connection between the pipe and tank must be accomplished with a watertight, resilient connector. This connector must be the sole means of sealing between the pipe and tank and cannot permit the infiltration of fluids or loss of vacuum around installed pipes (or pipe stubs) when tested in accordance with the requirements of this specification. Connectors conforming to ASTM C1644, fulfill the requirement of this section. 80

81. SD Water supply and drainage systems 81 6.4.7. Eurocode 2

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90. SD Water supply and drainage systems Concrete allowable crack widths REINFORCED CONCRETE (ACI 224R-90) EXPOSURE CONDITION CRACK WIDTH IN mm Dry air or protective membrane 0.4 Humidity, moist air, soil 0.3 Deicing chemicals 0.2 Seawater and seawater spray: Wetting and drying 0.2 Water-retaining structures 0.1 http://www.concretenetwork.com/concrete_cracks/allowable_crack_widths.htm 90

91. SD Water supply and drainage systems Problem: Determine the minimum concrete cover and maximum crack width for a septic tank buried in a soil with varying water table of sea water. 91

92. SD Water supply and drainage systems Solution: 92

93. SD Water supply and drainage systems Solution (II): 93

94. SD Water supply and drainage systems 6.5. Installation recommendations 94

95. SD Water supply and drainage systems 95 Concrete pipes Reference Manual, Humes, January 2009

96. SD Water supply and drainage systems 96 6.5.1. Piping installation For shallow installations (less than 1.30 meters) no shoring will be required.

97. SD Water supply and drainage systems When greater depths are needed, you can opt for two solutions: Leave natural slopes with a corresponding increase of excavation. Place shoring in the minimum width necessary to place the pipe. 97

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101. SD Water supply and drainage systems 6.5.2. Tank installation Proper installation of the tank is absolutely critical for maintaining structural integrity and watertightness. Many of the problems experienced with leakage can be attributed to incorrect installation procedures. In addition to damage to the tank, improper installation techniques could be a safety hazard. 101

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104. SD Water supply and drainage systems 6.5.3. Site Conditions The installation site must be accessible to a large trucks weighing up to 80,000 pounds (36,000 kg). The construction area should be free of trees, branches, overhead wires or parts of buildings that could interfere with the delivery and installation of the on-site wastewater tank. Most trucks will need to get within 3 to 8 feet (1 to 2.5 m) of the excavation to be unloaded. 104

105. SD Water supply and drainage systems Excavation Prior to excavation, identify and locate all buried utilities. Follow OSHA regulations governing excavation work at all times. Excavations should be sloped to comply with all construction safety requirements. 105

106. SD Water supply and drainage systems Bedding Proper use of bedding material is important to ensure a long service life of an on-site wastewater treatment system. Use imported bedding material as necessary to provide a uniform bearing surface. A good base should ensure that the tank would not be subjected to adverse settlement. Use a minimum of 4 inches (100 mm) thickness of sand or granular bed overlying a firm and uniform base unless otherwise specified. Tanks should not bear on large boulders or rock edges. 106

107. SD Water supply and drainage systems Sites with silty soils, high water tables or other “poor” bearing characteristics must have specially designed bedding and bearing surfaces. In the presence of high water tables, structures should be properly designed to resist floatation. 107

108. SD Water supply and drainage systems Proper compaction of the underlying soils and bedding material is critical to eliminate later settlement, which can ultimately occur in all tank installations regardless of the tank material. Potential tank settlement is measurable, predictable and preventable. Proper evaluation of the original soil, bedding materials, water table, backfill materials and potential soil-bearing stresses reduces the likelihood of later tank settlement. 108

109. SD Water supply and drainage systems Set the tanks level to provide the proper elevation drop from the inlet to the outlet. Worker safety is of primary importance. If it is necessary to have a worker enter the excavation to check elevation or compact bedding materials, use proper excavation methods that will prevent the sidewalls from collapsing. Alternatively, trench boxes may also be used if necessary. 109

110. SD Water supply and drainage systems Tank Placement Confirm the tank’s orientation prior to placement in the excavation. Check the bedding material and ensure that inlet penetrations face the residence. After placement, check that the tank is level. The slope of the sewer line and tank elevation should meet local plumbing and building codes. 110

111. SD Water supply and drainage systems 6.5.4. Lifting Devices Verify lifting apparatus such as slings, lift bars, chains and hooks for capacity, and ensure an adequate safety factor for lifting and handling products. The capacity of commercial lifting devices must be marked on the devices. 111

112. SD Water supply and drainage systems A factor of safety of at least 4 is recommended for lifting devices. Manufacturers of standard lifting devices should provide test data to allow selection of the proper lifting device. Because of their brittle nature, never use reinforcing bars as lifting devices. Use smooth bars made of steel conforming to ASTM A36, “Standard Specification for Carbon Structural Steel” instead. A factor of safety of at least 5 is recommended for lifting apparatus such as chains, slings, spreader beams, hooks and shackles. 112

113. SD Water supply and drainage systems 6.5.5. Joint Seals For two-piece tanks, use high-quality preformed joint seals. Surfaces should be clean. Ensure seals meet minimum compression and other installation requirements as prescribed by the seal manufacturer. Ambient temperatures below 50˚ F (10˚C) sometimes affect the compressibility of the sealant during installation. 113

114. SD Water supply and drainage systems Care must be taken to determine that tank sections installed on site have been properly sealed. Inspecting the joint area to determine that the tank sections have been properly seated helps prevent soil materials from entering the joint area during backfilling operation. Properly seal manholes and risers to prevent infiltration. 114

115. SD Water supply and drainage systems 6.5.6. Backfilling: Place backfill in uniform layers less than 24 inches (600 mm) thick. Backfill should be free of any large stones (greater than 3 inches [75 mm] in diameter) or other debris. 115

116. SD Water supply and drainage systems 116 6.6. Summary and conclusions

117. SD Water supply and drainage systems What design and construction criteria should be considered for maximum durability of concrete pipes and tanks? 117

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120. SD Water supply and drainage systems Bibliography Guidelines for the Design, Construction and Operation of Water and Sewerage Systems. Government of Newfoundland and Labrador. December 2005. Specifying Sustainable Concrete. The Concrete Centre. www.concretecentre.com/publications Concrete manufacturers association. Design manual for concrete pipe outfall sewers. April 2009. National Precast Concrete Association. Best practices manual. On-site Water Systems. 2005. Concrete Pipes Reference Manual. Humes. January 2009. Eurocode EC-2. Concrete Structures. ACI 211, “Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete” ASTM C494, Standard Specification for Chemical Admixtures for Concrete. www.concretecentre.com/publications Eurocode 2 ASTM C890, “Standard Practice for Minimum Structural Design Loading for Monolithic or Sectional Precast Concrete Water and Wastewater Structures” ASTM C913, “Standard Specification for Precast Concrete Water and Wastewater Structures” ASTM C1227, “Standard Specification for Precast Concrete Septic Tanks” IAPMO/ANSI CSA B66, “Design, Material, and Manufacturing Requirements for Prefabricated Septic Tanks and Sewage Holding Tanks” 120

121. SD Water supply and drainage systems ASTM C1017, Chemical Admixtures for Use in Producing Flowing Concrete ASTM C989, Standard Specification for Ground Granulated Blast Furnace Slag ASTM C260, Specification for Air-Entraining Admixtures for Concrete. ASTM C33, Standard Specification for Concrete Aggregates. ASTM C990, Standard Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants. ASTM C1644, Standard Specification for Resilient Connectors Between Reinforced Concrete On-Site Wastewater Tanks and Pipes. ASTM C309, Standard Specification for Liquid Membrane-Forming Compounds for Curing Concrete. 121

122. SD Water supply and drainage systems Ingenieros por el mundo in linkedin https://sites.google.com/site/glosariojc/ Please, German ingenieros por el mundo requested for German glossary! 122

123. SD Water supply and drainage systems Thank you for your attention! Any question? Cristina Vázquez-Herrero Water Supply and Drainage Systems in linkedin cvazquezh@udc.escvazquezh@udc.es, skype: cristina.vazquez.herrero 123