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Pressure Sewer DesignPressure Sewer DesignPressure Sewer DesignPressure Sewer Design
The Key Elements Toward SavingThe Key Elements Toward SavingThe Key Elements Toward Saving The Key Elements Toward Saving Time & Money for Your CustomersTime & Money for Your Customers
Pressure SewerPressure SewerA sanitary sewer system that utilizes a network of grinder pumps to• A sanitary sewer system that utilizes a network of grinder pumps to transport wastewater through small diameter pipes to a collection and treatment system.
• A grinder pump is a submersible pump designed to reduce• A grinder pump is a submersible pump designed to reduce wastewater particulate to a slurry through the use of a grinding mechanism
Wastewater Treatment l Service Connection
LateralPlant
Road
Pressure Sewer Collection System
Figure 1.1 -- Typical lakefront pressure sewer systemTypical lakefront pressure sewer system
Gravity sewers require big equipmentGravity sewers require big equipmentGravity sewers require big equipment, Gravity sewers require big equipment, major excavation and lift stationsmajor excavation and lift stations
Pressure Sewers do not rely onPressure Sewers do not rely onPressure Sewers do not rely on Pressure Sewers do not rely on limitations of gravitylimitations of gravity
• Wastewater is pumped through small diameter pipes following the contour of the land set in shallowcontour of the land, set in shallow trenches just below the frost line
• Lift stations are minimized or eliminated in virtually every installationWaste treatment plants for these• Waste treatment plants for these systems are less costly to build since the system is closed to yinfiltration and solid sizes and minimized.
Infrastructure Development CostsInfrastructure Development CostsInfrastructure Development Costs Infrastructure Development Costs are Lowerare Lower
Major excavation is eliminatedLabor and material costs can be dramatically reduceddramatically reducedEnvironmental disruption anddisruption and restoration are minimized Typical Pipe Size Ranges
Time to complete construction is
d dreduced
Pressure Sewers Provide…Pressure Sewers Provide…An economical solution to geo-technically challenging environmental conditions where gravity sewers may be impractical if not impossibleimpractical if not impossible
Examples include:oRocky soiloHilly terrainoShallow bedrockoShallow bedrock oHigh water tableso Long flat terrainoSlow growth areasoExisting structures/roads
Pressure Sewers: A Proven TechnologyPressure Sewers: A Proven Technology
First used in the early 1970’sProvides daily service to millions of users worldwideDemonstrated excellent performance, high reliability and low Operating and Maintenancereliability and low Operating and Maintenance costs
Typical Residential InstallationTypical Residential Installation
A grinder pump station is located in the yard or basement of each homeWastewater flows into the station from the building’s sewer line (typically 4”)The basin contains a grinder pump levelThe basin contains a grinder pump, level sensors, valves and discharge piping
Typical Residential Grinder Pump Typical Residential Grinder Pump
• A pressure sewer
yp pyp pSite ComponentsSite Components
• A pressure sewer collection line is laid along the edge of the roadway, following the contour offollowing the contour of the land
• The pressure sewer collection line delivers the wastewater to a central treatment system, y ,manhole, or force main
• Wastewater may be transported severaltransported several thousand feet to a discharge point at a higher elevationhigher elevation
Residential Grinder Pump PackageResidential Grinder Pump Package
Basin
Pump Control and/or Alarm Panel
Basin
Piping / Valves
Level Sensors
Grinder Pump
Typical Commercial StationTypical Commercial StationLarger pump station basin for added storage capacityTwo submersible grinder pumps toTwo submersible grinder pumps to provide redundancyThe control panel will include an alarm
d lt t t hand an alternator to run each pump every other cycleNote: Code requirements may be more stringent for
i l i h f id i l icommercial stations than for residential stations.
Operating costsOperating costsOperating costs for a typical residential station can be less than $3.00 per month** Based on 10 cents per Kilowatt Hour and 300* Based on 10 cents per Kilowatt Hour and 300 Gallons per day
Pressure Sewerage Projects A Selection of Design IssuesA Selection of Design Issues
(Keep It Simple, PSS is Different, Not Difficult)
Steve WallacePressure Sewer Solutions Pty Ltd.
Ph +61 2 9584 1177Ph +61 2 9584 1177October 2009
Design IntroductionDesign Introduction
Design considerations - ins and outs of design
Performance profile a systems will achieve
Design ConsiderationsDesign ConsiderationsDesign Parameters Development
Masterplan layout development e.g. Existing and ultimate property numbers Future Sewer Areas etcproperty numbers, Future Sewer Areas etc.
Dwelling occupation profile e.g. Vacation houses
Non residential loadings e.g. Commercial properties and point loadspoint loads
Storm allowance (I&I)
Peak instantaneous flows determination methodology, average day peak and after power outage flows. Propertyaverage day peak and after power outage flows. Property discharge rate = 757 l/d/dwelling (~200 gal / day)
Design ConsiderationsDesign ConsiderationsDesign ConsiderationsDesign Considerations
Design Parameters Development (cont)System hydraulic analysis methodology and friction loss factors
Downhill pumping considerations
Ai t (b d d )Air management (buoyancy and odor)
Downstream capacity requirement for systems normal operation and after power outage flowsand after power outage flows
Wastewater flow velocities
Max pump TDH and pump product selection
Design ConsiderationsDesign Considerations
Site Considerations
Environmental, cultural and geotechnical project issues
M i l ti d t t iMain locations and property easement issues
Future mains extensions
Electricity quality - low and high voltage
Design ConsiderationsDesign Considerations
Property ConsiderationsCommunity management plan
Property plumbing & electrical standards and upgrades
Project connection rate e.g. backlog vs. development –long or slow connection period
General trade waste issues e.g. Grease arrestors
Swimming pool backwash
Design ConsiderationsDesign Considerations
Other Issues To ConsiderConstruction Methodologies
Construction Materials Selection
Commissioning Plan
Authorities standards, requirements and charges
Systems operators criteria and service structure should beSystems operators criteria and service structure should be designed into the system
P k Fl C l l ti M th dP k Fl C l l ti M th dPeak Flow Calculation Methods Peak Flow Calculation Methods ((Peak Instantaneous Flows Determination Methodology)Peak Instantaneous Flows Determination Methodology)
35
30
35
Assumptions757L/ET/day
25
RATIONAL METHOD
15
20
Peak
Flo
w (L
/S) RATIONAL METHOD
PROBABILITY METHOD(Instantaneous Peak)
r - FACTOR + No StormAllowance
10
Allowance
CEP = r-FACTOR+50%Storm Allowance
0
5
0 100 200 300 400 500 600 700 800 900 10000 100 200 300 400 500 600 700 800 900 1000ET's
Sewage FlowsSewage FlowsSewage Flows Sewage Flows ((Peak Instantaneous Flows Determination Methodology)Peak Instantaneous Flows Determination Methodology)
35
30
35
Note:ET = 1 House Connection5 l/s = ~80 Gal/ Min10 l/s = ~158 Gal/ Min
25
)
PROBABILITY METHOD(757L/ET/day)
15
20
Peak
Flo
w (L
/S)
Recorded Flows Warneet & Cannons Creek Instantaneous
Design Flows (instantaneous peak)Tooradin, Warneet &
Cannons Creek
10Recorded Flows
Tooradin Instantaneous Peak
Cannons Creek Instantaneous Peak
Tooradin (Recorded 400L/ET/day)
Warneet & Cannons
0
5
0 200 400 600 800 1000
Recorded FlowsTooradin Average of Daily Peak Flows
Recorded FlowsWarneet & Cannons Creek
Average of Daily Peak FlowsRecorded FlowsAlbany Average Daily Peak Flow
Creek (Recorded 400L/ET/day)
0 200 400 600 800 1000
ET's
Pressure Sewer Solutions P/L Pressure Sewer Solutions P/L Peak Flow Calculation Method Peak Flow Calculation Method ((Peak Instantaneous Flows Determination Methodology)Peak Instantaneous Flows Determination Methodology)
Note:400 Litres = ~106 Gal1000 Litres = ~ 264 Gal
Litres//Property/day
Weekly Flow to WWTPWeekly Flow to WWTPWeekly Flow to WWTP Weekly Flow to WWTP (Downstream capacity requirement)(Downstream capacity requirement)
Suburban CommunitySuburban Community 4 l/s = ~63 Gal / Minyy3 Days of Flow3 Days of Flow
PSS Fl t D t 08 10 J l '06 (S t M )PSS Flowmeter Data 08-10 July '06 (Sat-Mon)
6
7
Owen St Jamberoo + Golden Valley Rd Jamberoo 15 sec.
Calculated Peak Flow
5
yOwen St Jamberoo + Golden Valley Rd Jamberoo 5 min.. SmoothedModel Dry Weather Curve (assumed)
Calculated Average Day Peak Flow
3
4
Flow
(L/s
)
2
0
1
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 AVacation Community AVacation Community A Vacation Community A 12 Months of Flow Data12 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 BVacation Community BVacation Community B Vacation Community B 2 Months of Flow2 Months of Flow
5 l/s = ~79 Gal / Min5 l/s = ~79 Gal / Min
Calculated Peak Flow
Calculated Average Peak Flow
General Trade Waste IssuesGeneral Trade Waste Issues
Food Shop - Wastewater pre treatment must be assessed.This existing food shop grease arrestor is too small therefore inadequate treatment for connection to any sewerage systeminadequate treatment for connection to any sewerage system and will shorten the life of your pump unit if connected.
Inflow and InfiltrationInflow and Infiltration
Does it happen in a pressure sewer system?
How is it managed and eliminated?
Wet Flow Wet Flow –– Does It Happen?Does It Happen?
THURSDAYS WET WEATHER INSTANTANEOUS FLOWSTOORADIN JUNE 2003 - JUNE 2004(DRY WEATHER - MAX, MIN, AVE)
4 5
3.5
4
4.5Design
Instantaneous Peak Sewage Flow for
235 property connections= 6.96L/S
4 l/s = ~64 Gal / Min
2.5
3
W (L
/S) Maximum
RecordedADWF = 1.29L/s
1.5
2
FLO
W Average
Minimum
31 July 2003(8mm)
14 A 2003
2 l/s = ~32 Gal / Min
0
0.5
1 14 Aug 2003(5mm)
12 Feb 2004(9mm)
10-Jun-04(14mm)
0 3 6 9 12 15 18 21 0
TIME
Wet Weather FlowWet Weather FlowPSS Flowmeter Data 21-25 July '06 (Fri-Tues) with Rainfall
5
6
20
24Golden Valley Rd Jamberoo 890011 15 sec.890011 15min. (smoothed)Rain Kiama5 l/s = ~79 Gal / Min
4
5
s)
16
20
all (
mm
)
2
3
Flow
(L/s
8
12
Cum
ulat
ive
Rai
nfa
1 4
C
021/7 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
0
“Rainfall events graph indicates no noticeable increase in flows during rainfall. A check of the d t t f i t ti h d th t th l i f ll t d i th l t h lfdownstream transfer sewage pumping station showed that other larger rainfall events during the last half of 2007 did not show any noticeable wet weather flows” — 16/4/07 A. Bovis, Sydney Water Corporation.
Wet Flow Wet Flow –– Does It Happen?Does It Happen?
Litres
250000
Hea
vy R
ain STP INFLOW VOLUME
200000
H 21,000 L = ~5,547 Gal
100000
150000
Litres
Wet
Day
Rai
n
Wet
Day
50000
7,000 L = ~1,850 Gal
0
6/02/2
007
7/02/2
007
8/02/2
007
9/02/2
007
10/02
/2007
11/02
/2007
12/02
/2007
13/02
/2007
14/02
/2007
15/02
/2007
6 7 8 9 10 11 12 13 14 15
After Power Outage FlowsAfter Power Outage Flows
What does it mean to a systems design and operation?
After Power Outage FlowsAfter Power Outage Flows
18 l/s = ~285 Gal / Min
4 l/s = ~63 Gal / min
After Power Outage After Power Outage FlowsFlows
Air ManagementAir Management
• What is it?
• Buoyancy Head
• Moving and expelling air within the system
M i Ai I PiM i Ai I PiMoving Air In Pipes Moving Air In Pipes ((Downhill Pumping Considerations)Downhill Pumping Considerations)
0.6 M/s = ~ 2’ / sec
Referenced From Wallingford Institute Air in Pipes Study
OdorOdor & Corrosion Issues and Control& Corrosion Issues and Control
Odor needs to be considered in the following context.• Whilst sewerage is under pressure in the main odor will• 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.
OdorOdor & Corrosion Issues and Control& Corrosion Issues and Control
• Methods of odor management involve the following:
Design system with short wastewater retention time in pipep pDischarge wastewater to location where odor wont be detectedChemical dosing into the wastewater flowChemical dosing into the wastewater flowScrubbing the gas phase release or high level ventFlushing water into the mainSelection of non-corrosive materials and protecting other surface structures
Odor Control FacilityOdor Control Facility
Odor Control FacilityOdor Control Facility
Air ScrubberAir Scrubber
ConclusionConclusion
Consider issues such as:
• Peak wastewater flow calculation methods and• 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 WallacePressure Sewer Solutions Pty Ltd.
Ph +61 2 9584 1177Ph +61 2 9584 1177
Walt ErndtEnvironment One Corporation
Ph 518.346.6161