Pressure Sewer Design

The Key Elements Toward Saving Time & Money for Your Customers Pressure Sewer

• A system that utilizes a network of grinder pumps to transport wastewater through small diameter pipes to a collection and treatment system. • A is a designed to reduce wastewater particulate to a slurry through the use of a grinding mechanism

Wastewater Treatment Plant Service Connection Lateral

Road

Pressure Sewer Collection System

TypicalFigure 1.1lakefront -- Typical lakefront pressure pressure sewer sewer systemsystem Gravity sewers require big equipment , major excavation and lift stations Pressure Sewers do not rely on limitations of gravity

• Wastewater is pumped through small diameter pipes following the contour of the land , set in shallow trenches just below the frost line • Lift stations are minimized or eliminated in virtually every installation • Waste treatment plants for these systems are less costly to build since the system is closed to infiltration and solid sizes and minimized. Infrastructure Development Costs are Lower

y Major excavation is eliminated y Labor and material costs can be dramatically reduced y Environmental disruption and restoration are minimized Typical Size Ranges y Time to complete construction is reddduced Pressure Sewers Provide… y An economical solution to geo-technically challenging environmental conditions where gravity sewers may be impractical if not impossible y Examples include: o Rocky soil o Hilly terrain o Shallow bedrock o High water tables o Long flat terrain o Slow growth areas o Existing structures/roads Pressure Sewers: A Proven Technology y First used in the early 1970’s y Provides daily service to millions of users worldwide y Demonstrated excellent performance, high reliability and low Operating and Maintenance costs Typical Residential Installation y A grinder pump station is located in the yard or basement of each home y Wastewater flows into the station from the building’s sewer line (typically 4”) y The basin contains a grinder pump , level sensors, valves and discharge piping Typical Residential Grinder Pum p Site Components

• A pressure sewer collection line is laid along the edge of the roadway, following the contour of the land • The pressure sewer collection line delivers the wastewater to a central treatment syy,stem, , or force main • Wastewater may be transported several thousand feet to a discharge point at a higher elevation Residential Grinder Pump Package

Basin Pump Control Piping / Valves and/or Alarm Panel

Level Sensors

Grinder Pump Typical Commercial Station

y Larger pump station basin for added storage capacity y Two submersible grinder pumps to provide redundancy y The control panel will include an alarm andltttd an alternator to run eac h pump every other cycle y Note: Code requirements may be more stringent for commercilial stat ions t han for res ident ilial stat ions. Operating costs y Operating costs for a typical residential station can be less than $3.00 per month* y * Based on 10 cents per Kilowatt Hour and 300 Gallons per day Pressure Projects A Selection of Design Issues

(Keep It Simple, PSS is Different, Not Difficult)

Steve Wallace Pressure Sewer Solutions Pty Ltd. [email protected] www.pssolutions.net.au Ph +61 2 9584 1177 October 2009 Design Introduction

y Design considerations - ins and outs of design

y Performance profile a systems will achieve Design Considerations Design Parameters Development y Masterplan layout development e.g. Existing and ultimate property numbers, Future Sewer Areas etc . y Dwelling occupation profile e.g. Vacation houses y Non residential loadings e.g. Commercial properties and point loads y Storm allowance (I&I) y Peak instantaneous flows determination methodology, average day peak and after power outage flows. Property discharge rate = 757 l/d/dwelling (~200 gal / day) Design Considerations

Design Parameters Development (cont) y System hydraulic analysis methodology and friction loss factors

y Downhill pumping considerations

y Air management (b uoyancy an d o dor )

y Downstream capacity requirement for systems normal operation and after power outage flows

y Wastewater flow velocities

y Max pump TDH and pump product selection Design Considerations

Site Considerations y Environmental, cultural and geotechnical project issues y MiMain loca tions an d proper ty easemen tit issues y Future mains extensions y Electricity quality - low and high voltage Design Considerations

Property Considerations y Community management plan

y Property & electrical standards and upgrades

y Project connection rate e.g. backlog vs. development – long or slow connection period

y General trade waste issues e.g. Grease arrestors

y Swimming pool backwash Design Considerations

Other Issues To Consider y Construction Methodologies y Construction Materials Selection y Commissioning Plan y Authorities standards, requirements and charges y Systems operators criteria and service structure should be designed into the system PkFlClltiMthdPeak Flow Calculation Methods ((PeakPeak Instantaneous Flows Determination Methodology)

35

30 Assumptions 757L/ET/day

25

RATIONAL METHOD 20

PROBABILITY METHOD (Instantaneous Peak)

15 Peak Flow (L/S) Flow Peak r - FACTOR + No Storm Allowance

CEP = r-FACTOR+50% Storm Allowance 10

5

0 0 100 200 300 400 500 600 700 800 900 1000 ET's Flows ((PeakPeak Instantaneous Flows Determination Methodology)

35 Note: ET = 1 House Connection 30 5 l/s = ~80 Gal/ Min 10 l/s = ~158 Gal/ Min

25

PROBABILITY METHOD (757L/ET/day) )) 20 Design Flows (instantaneous peak) Tooradin, Warneet & Cannons Creek 15 Peak Flow (L/S Recorded Flows Warneet & Cannons Creek Instantaneous Peak

10 Recorded Flows Tooradin Tooradin Instantaneous (Recorded 400L/ET/day) Peak Warneet & Cannons Creek 5 (Recorded 400L/ET/day)

Recorded Flows Recorded Flows Recorded Flows Warneet & Cannons Creek Albany Average Tooradin Average of Average of Daily Peak Flows Daily Peak Flow Daily Peak Flows 0 0 200 400 600 800 1000 ET's Pressure Sewer Solutions P/L Peak Flow Calculation Method ((PeakPeak Instantaneous Flows Determination Methodology)

Note: 400 Litres = ~106 Gal 1000 Litres = ~ 264 Gal

Litres/ Property /day Weekly Flow to WWTP

(Downstream capacity requirement) Suburban Community 4 l/s = ~63 Gal / Min 3 Days of Flow

PSS Fl Flowmeter t D Data t 08 08-10 10Jul Jy '06 l '06(Sat (S-Mon t M) ) 7 Calculated Peak Flow

6 Owen St Jamberoo + Golden Valley Rd Jamberoo 15 sec. Owen St Jamberoo + Golden Valley Rd Jamberoo 5 min.. Smoothed Model Dry Weather Curve (assumed)

5 Calculated Average Day Peak Flow

4

Flow (L/s)3

2

1

0 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM Vacation Community A 12 Months of Flow Data

10 l/s = ~158 Gal / Min

S/O Calculated Peak Flow

PSS Calculated Peak Flow

PSS Calculated Average Peak Flow Vacation Community B 2 Months of Flow

5l/s=~79Gal/Min5 l/s = ~79 Gal / Min

Calculated Peak Flow

Calculated Average Peak Flow General Trade Waste Issues

y Food Shop - Wastewater pre treatment must be assessed. y This existing food shop grease arrestor is too small therefore inadequate treatment for connection to any sewerage system and will shorten the life of your pump unit if connected. Inflow and Infiltration

y Does it happen in a pressure sewer system? y How is it managed and eliminated? Wet Flow – Does It Happen?

THURSDAYS WET WEATHER INSTANTANEOUS FLOWS TOORADIN JUNE 2003 - JUNE 2004 (DRY WEATHER - MAX, MIN, AVE)

454.5 Design 4 l/s = ~64 Gal / Min Instantaneous Peak 4 Sewage Flow for 235 property connections 3.5 = 6.96L/S Recorded ADWF = 1.29L/s 3

2.5 Maximum (L/S)

WW 2 l/s = ~32 Gal / Min Average 2 FLO Minimum

1.5 31 July 2003 (8mm) 1 14 Aug 2003 (5mm) 12 Feb 2004 0.5 (9mm) 10-Jun-04 (14mm) 0 0 3 6 9 121518210 TIME Wet Weather Flow

PSS Flowmeter Data 21-25 July '06 (Fri-Tues) with Rainfall 6 24 Golden Valley Rd Jamberoo 890011 15 sec. 890011 15min. (smoothed) 5 l/sRain =Kiama ~79 Gal / Min 5 20

4 16 ll (mm) ) aa ss

3 12 Flow (L/

2 8 umulative Rainf CC

1 4

0 0 21/7 12 AM 21/7 12 PM 22/7 12 AM 22/7 12 PM 23/7 12 AM 23/7 12 PM 24/7 12 AM 24/7 12 PM 25/7 12 AM 25/7 12 PM 26/7 12 AM

“Rainfall events graph indicates no noticeable increase in flows during rainfall. A check of the downs tream trans fer sewage pumpi ng s ta tion s howe d tha t o ther larger ra in fa ll even ts dur ing the las t ha lf of 2007 did not show any noticeable wet weather flows” — 16/4/07 A. Bovis, Sydney Water Corporation. Wet Flow – Does It Happen?

Litres n STP INFLOW VOLUME 250000 eavy Rai

HH 21,000 L = ~5,547 Gal 200000

150000 y y Litres Wet Da 100000 Rain Wet Da 7,000 L = ~1,850 Gal

50000

0

7 7 7 7 0 007 07 007 /20 2 /20 2 /02/200 /02 /02/200 /02/200 /02/2007 /02/2007 /02/ /02 /02/2007 /02/ 6 7 8 9 10 11 12 13 14 15 After Power Outage Flows

y What does it mean to a systems design and operation? After Power Outage Flows

18 l/s = ~285 Gal / Min

4 l/s = ~63 Gal / min After Power Outage Flows Air Management

• What is it?

• Buoyancy Head

• Moving and expelling air within the system MiMoving Ai AiIPir In Pipes (Downhill Pumping Considerations)

0.6 M/s = ~ 2’ / sec

Referenced From Wallingford Institute Air in Pipes Study Odor & Corrosion Issues and Control

Odor needs to be considered in the following context. • Whilst sewerage is under pressure in the main odor will not be released.

• When the pressure line is discharged to the atmosphere (liquid and gas phase) hydrogen sulphide may be released.

• May be odorous and corrosive to system components. Odor & Corrosion Issues and Control

• Methods of odor management involve the following:

x Design system with short wastewater retention time in pppipe x Discharge wastewater to location where odor wont be detected x Chemical dosing into the wastewater flow x Scrubbing the gas phase release or high level vent x Flushing water into the main x Selection of non-corrosive materials and protecting other surface structures Odor Control Facility Odor Control Facility Air Scrubber Conclusion y Consider issues such as:

• Peak wastewater flow calculation methods and understand where the systems performance boundaries are.

• Type of projects e.g. urban residential, vacation community etc.

• Storm allowance (I & I)

• After power outage flows

• Air management

◦ Trade waste treatment Steve Wallace Pressure Sewer Solutions Pty Ltd. [email protected] www.pssolutions.net.au Ph +61 2 9584 1177

Walt Erndt Environment One Corporation [email protected] www.eone.com Ph 518.346.6161