Sanitary Sewer 101. Jan. 12, 2016 Keith Fisher, P.E. Director of Public Works

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1 Sanitary Sewer 101 Jan. 12, 2016 Keith Fisher, P.E. Director of Public Works

2 What We Will Cover -What is Sanitary Sewer? -Components -History -What types of systems are there? -What types of materials are used? -What types of problems are there? -Sanitary Sewer Overflows (SSO) -Inflow & Infiltration (I&I) -Where does it go? -What maintenance is involved? -Who pays for it?

3 What Is Sanitary Sewer? A sanitary sewer system is a series of pipes that form a collection system to convey wastewater from residential, industrial, and commercial areas to a treatment facility.

4 What Is Sanitary Sewer? Private building lateral sewer A private building lateral sewer is a 6-inch pipe that conveys sewage from the building to the public sewer main, usually under the street. Mainline sewer Mainline sewers are pipes that collect sewage from buildings and flow by gravity to the treatment plant. Manholes A manhole is a structure, usually circular, at the surface that allows access to the sewer pipes buried below

5 What Is Sanitary Sewer? Inverted siphon An inverted siphon is a pipe that must dip below an obstruction and will normally form a U-shaped flow path. The liquid flowing in one end simply forces liquid up and out the other end. Inverted siphons are commonly used when a sewer pipe must be routed under a river or other deep obstructions. Force mains Force main sewer pipes are where wastewater is pumped (forced) under pressure to a specific location. Force mains are used when sewage cannot flow by gravity. Lift (pump) stations A lift station is a location in the collection system where wastewater is collected (wet well) and then pumped to another location. The purpose of a lift station is to lift (pump) wastewater to a higher elevation where it can flow by gravity.

6 History of Sanitary Sewer Disposed into gutters, ditches, etc. Illness, disease, odors, unpleasant to see Outhouses were developed Outside Smell Periodically relocated Underground pipe collection system Various treatment methods Not visible to public Reduction in illness/health concerns

7 History of Sanitary Sewer Did you know? The phrase manhole even though some people today want to change it for gender-sensitivity reasons was first used to describe the access holes between the decks of old, all-male, sailing ships. The word manhole (initially) had nothing to do with sewers. In fact, some believe the word sewer is derived from the term seaward in Old English. Early sewers in the London area were open ditches which led to the Thames River, and from there on down to the sea ( seaward ).

8 What Types Of Systems Are There? Open Systems (No longer allowed in developed countries) Closed Systems Combined Sewer Separate Sewer Pressurized Sewer Septic Systems Aerobic System

9 What Types Of Systems Are There? Open Systems (No longer allowed in developed countries)

10 What Types Of Systems Are There? Open Systems (No longer allowed in developed countries)

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12 What Types Of Systems Are There? COMBINED SEWER

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14 SANITARY SYSTEM STORM SYSTEM

15 What Types Of Systems Are There? SEPARATE SEWER

16 What Types Of Systems Are There? PRESSURIZED SEWER Pressurized sewers differ from conventional gravity collection systems, because they use pumps instead of gravity to transport wastewater

17 What Types Of Systems Are There? PRESSURIZED SEWER

18 What Types Of Systems Are There? SEPTIC SYSTEM

19 What Types Of Systems Are There? SEPTIC SYSTEM

20 What Types Of Systems Are There? SEPTIC SYSTEM

21 What Types Of Systems Are There? AEROBIC SYSTEM Involves injecting septic systems with oxygen in order to stimulate growth of aerobic bacteria to break down and filter wastewater.

22 What Types Of Systems Are There? Conventional Septic System +Cheaper +Availability +Less Maintenance -Dirtier Effluent -Requires More Space -Less Efficient -Smell Aerobic Septic System +Cleaner +More Efficient +Smaller Area -Complex -Costly -Require Electricity -More Maintenance

23 City vs. Customer Responsibility

24 What Types Of Materials Are Used? Types of Pipes Polyvinyl chloride (PVC ) Vitrified Clay Pipe (VCP) Asbestos Cement (AC) Concrete Cast Iron

25 PVC PIPE

26 VCP PIPE

27 VCP PIPE

28 AC PIPE

29 CONCRETE PIPE

30 CAST IRON PIPE

31 CAST IRON PIPE CAST IRON PIPE

32 What Types Of Problems Are There? Inflow & Infiltration Sanitary Sewer Overflows Channeling of Aging Cast Iron Pipes & Clay Pipes Pipe Corrosion Tree Root Intrusion Broken Pipes Due to Soil Expansion

33 Inflow & Infiltration (I&I) When I/I enters collection system pipes, it can exceed the flow capacity of the pipes and result in surcharging, basement backups, and sanitary sewer overflows (SSO). I/I in the collection system can also lead to very high flows entering the treatment facility and can lead to wastewater pumping and treatment problems. November 27, 2015 Plano (2 overflows 200,000 gallons) November 29, 2015 Ft. Worth (5 overflows 800,000 gallons) November 30, 2015 Dallas (5 overflows 500,000 gallons)

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35 Sanitary Sewer Overflow

36 Where Does It Go? Potable water is provided by the water supply system into a building and is used to flush or drain wastes into the building s sanitary sewer pipes and into the wastewater collection system. Wastewater is conveyed through gravity sewers, lift stations, and force mains until it makes its way into the headworks of a wastewater treatment plant. The wastewater is then treated by both physical and biological unit operations and processes and then clean water is discharged into a receiving water body.

37 Where Does It Go? The Trinity River Authority (TRA) services all of Keller s wastewater from three basins. The Big Bear and Little Bear Basin s wastewater flows to TRA s Central Regional Wastewater Treatment Plant in Irving and the Denton Creek Basin wastewater flows to the Denton Creek Wastewater Treatment Plant in Roanoke. The City has approximately 1,800 homes without a sewer system adjacent to their home.

38 What Maintenance Is Involved? Cleaning Root removal Televising Flow monitoring Smoke testing Manhole inspections Lift station maintenance Manhole rehabilitation Mainline rehabilitation Private sewer inspections Private sewer I/I removal Fat, oil and grease (FOG) control program

39 Who Pays For It? The City of Keller has constructed and paid for sanitary sewer improvements in the following ways: Capital Improvement Projects (Water/Wastewater Enterprise Fund and Impact Fees) Developer Projects (residential and commercial) Citizen Assessment (Windsor Forest Addition) Cost Sharing builder pays for materials, city performs the installation. (not more than 500 of line) Developer Agreements (cost sharing)

40 Questions?