UG Sewer Class Project

8/12/2019 UG Sewer Class Project

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UNIVERSITY OF GUYANA

FACULTY OF TECHNOLOGY

DEPARTMENT OF CIVIL ENGINEERING

CIV 413Environmental Engineering

Group 2

Project Title:

Evaluation & Redesign of University of

Guyana Sanitary Sewer System

Lecturer: Mr. M. Jackson

Date: January 04, 2011


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12.1 General ........................ ......................... .......................... ......................... ........................... ..... 19

12.2 Quantities ........................ .......................... ......................... .......................... ........................... 20

12.3 Materials .......................... .......................... .......................... ......................... .......................... . 20

12.4 Prices and Currency ....................... ......................... ........................... ......................... .............. 21

12.5 Rights of Employer ........................ ......................... ........................... ......................... .............. 23

12.6 Site Access and Storage .......................... ......................... .......................... .......................... ..... 23

12.7 Site Installation ......................... .......................... ......................... .......................... .................. 23

12.8 Duration ....................... ......................... .......................... ......................... ........................... ..... 24

13.0 Priced Bill of Quantity .................................................................................................................... 25

14.0 Recommendations .......................... ......................... ........................... ......................... .............. 41

15.0 Conclusion ......................... .......................... .......................... ......................... .......................... . 42

16.0 References ......................... .......................... .......................... ......................... .......................... . 43

17.0 Appendices ........................ .......................... ......................... .......................... ........................... 44


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1.0 Executive Summary

This report summarizes the findings for the redesign of the Sanitary Sewer System located

on the University of Guyana, Turkeyen Campus.

The guidelines for the proposed design are based on the design criteria and considerations

of the Sewer and Drainage Facilities Design Manual, Council Adoption September 2006,

revised June 2007 as well as the Bureau of Engineering Manual - Part F. The objective of

this study is to redesign the University of Guyana sanitary sewer system which serves a

land area of eighty (80) acres and an estimated population of six thousand (6,000)

inclusive of staff and students. The existing system comprises of minor four 4diameter

P.V.C pipes and one 12inch diameter P.V.C pipe which serves as the main collector from

the wet well to the treatment plant for disposal.

The existing minor sanitary sewers which are connected to the tributary buildings serve

sixty-six (66) manholes which then flow to the major sewer which has a total length of

1,846 feet. The design will utilize Mannings equation for flow along with a recommended

minimum discharge of 2.5 ft3/sec to achieve an efficient system.


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2.0 Introduction

Wastewater is a broad descriptive term for liquids and waterborne solids originating from

domestic, commercial and industrial activities as well as water that has been contaminated

by the activities of humans and whose quality have been degraded. Wastewater is usually

discharged to a sewerage system. The term sewage has been used to describe wastewater

containing only sanitary waste but it technically denotes any wastewater that passes

through a sewer1.

Sewage or wastewater disposal comprises of several processes for the collection, treatment

and sanitary disposal of wastewater from households and industrial plants. A sanitary

sewer is defined as a conduit, which is designed for wastewater discharges from domestic,

commercial and industrial institutions. A system of sewers is generally called a sewerage

system.

The composition of wastewater is analyzed using several physical, chemical and biological

measurements. The most common analyses include the measurements of solids,

biochemical oxygen demand (BOD), chemical oxygen demand (COD) and pH. The solid

wastes include dissolved and suspended solids. Dissolved solids are the materials that will

pass through filter paper while suspended solids are those that do not. Suspended solids

are further divided into settleable and non settleable solids, depending on the quantity of

solids that will settle out of 1 liter of wastewater in 1 hour. All these classes of solids can be

divided into volatile or fixed solids, volatile solids generally being organic materials and the

fixed solids being inorganic materials or mineral matter.

The concentration of organic matter is measured by the BOD and the COD analyses. TheBOD is the amount of oxygen used over a five day period by microorganisms as they

decompose the organic matter in sewage at a temperature of 20C. Similarly, the COD is the

amount of oxygen required to oxidize the organic matter by use of dichromate in an acid

1Environmental Engineering Merrit, S. Frederick, Lofting, M. Ken and Ricketts, Jonathan T. Standard Handbook

for Civil Engineers, 4thEdition, New York: Mc Graw Hill Book Company,1996


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solution and to convert it to carbon dioxide and water. The value of COD is always higher

than that of BOD because many organic substances can be oxidized chemically but cannot

be oxidized biologically. Commonly, BOD is used to test the strength of treated and

untreated municipal and biodegradable industrial wastewaters. COD is used to test the

strength of wastewater that is either not biodegradable or contains compounds that inhibit

activities of microorganisms.

Sewer systems are classified as:

1. Sanitary Sewer system - is comprised exclusively of sewers which convey liquidwastes from residences, commercial buildings, industrial plants and institutions;

2. Storm Sewer system - conveys storm water runoff from buildings, streets and othersurfaces but excludes domestic, commercial and industrial wastewater. Storm

water runoff is that portion of precipitation that flows over these types of surfaces

during and after a storm;

3. Combined Sewer system - is comprised of a network of sewers that collect andconvey both sanitary and storm water runoff.


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3.0 Background

The sewerage system of the University of Guyana was laid down in 1969 shortly before the

campus was opened and consists of approximately 66 manholes within a network ofgravity pipes. Each manhole is approximately 2ft wide 2ft long 2ft9 in. deep. These

manholes are strategically located at points:

1. Where there is a significant change of direction or grade;2. To allow access to the sewer at strategic locations to facilitate maintenance,

inspection and cleaning.

The population it served in October 1969 was approximately 164 students and staff2.

Today, 41 years later the buildings on the campus increased have to 25 and the students

and staff population increased to over 6000 persons. 3

The existing sewerage system consist of a network of pitch fibre and PVC gravity sewer

pipes draining to Du-O-Jet sewage ejectors. The pitch fibre and PVC pipes are mainly of

4diameter. The sewage ejectors operate by pneumatically ejecting the collected

wastewater from the university complex a distance of approximately 1846ft via a 12

diameter discharge PVC pipeline to a model V treatment plant that is no longer functional. 4

This plant was previously responsible for treating the sewage by utilizing a process called

the activated sludge process, after which its effluent is discharged into a nearby drainage

trench.

The Smith & Loveless lift station consist of Du-O-Jet ejectors located just north of UG s

library and consist of three compartments within a cylindrical steel chamber. The top

compartment accessible from ground level houses the ejector, controls and compressor.

The middle section is a combination of air- storage tanks and chamber for the valves and

manifold. The bottom compartment is the sewage receiver. The lift station receives the

2University of Guyana Website3Office of the Assistant Registrar4Smith & Loveless Inc.


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sewage from the sewer lines through the inlet gate valve, thru the inlet check valve and into

the sewage receiver. When the sewage fills the receiver an electrical circuit is completed

from the electrode, through the liquid to the ground at the receiver walls, energizing the DC

relay which activates the three way air valves, through a hallow electrode air pipe, into the

sewage receiver. The pressure forces the sewage up the inlet pipe, through the discharge

check valve and gate valve into the force main, which discharges the sewage through a

750ft, 12 PVC pipelines to the treatment plant. This pipe is buried at a grade of 1 in 200

and there is 1ft of compacted sand fill under the pipe with a 2inch thick concrete slab above

it. Three liquid level displacement switches in the wet well controls the pumping cycle.

With a rising wet well, the low lever ON displacement switch is tilted and the base pump

starts. If the wet well level continue to rise, the high level ON displacement switch setting

and the low level OFF displacement switch shut off both pumps. Every eight (8) hours the

pumps are alternated so that the standby pump becomes the base pump.

In Guyana there are only two sewage treatment plants utilizing the activated sludge

process; the model V treatment plant being used by the University of Guyana, which was

acquired in the mid- 70s, at value recorded by the Bursary as twenty three million Guyana

dollars (G$23,000,000). The treatment plant was manufactured by SMITH & LOVELESS,

Inc., based in Lenexa, Kansas. This treatment plant was factory built and utilizes a

rectangular aeration tank with two truncated pyramid shaped clarifiers. The other is the

Tucville Sewage Treatment Plant, which was designed by Loius Berger Inc., in association

with local consultants, Aubrey Barker Associates to treat wastewater by extended aeration,

activated sludge process. However, due to lack of proper maintenance and unavailability of

spares and replacement parts, the works has ceased to function as intended.


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4.0 Statement of Problem

The University of Guyana sewerage system was designed for a population of approximately

1500 persons in 1969, as only 10 buildings were existent at the time. Today, forty one

years later, the number of buildings on the campus has increased to 25 and the student and

staff population increased to over 6,000 persons. The sewage lines leading from some of

these new buildings were connected to the existing University sewerage system while for

others, there are septic tanks constructed to dispose their sewage. Due to the increase in

population and buildings at the University of Guyana, there is an increased hydraulic load

on the sewers and hence, to cater for this scenario there is a need to evaluate the existing

capacity and design an adequate sewerage system based on the existing population and the

population growth for the next 25 years.

5.0 Objectives

1. To evaluate the adequacy of the current sewer system in providing for the needs ofthe current population as well as its ability to serve future increases in population.

2. If it is established that the existing system is inadequate; a redesign of the systemwill be undertaken.


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6.0 Scope and Limitations

1. This project is confined to the University of Guyana Sewer System and focuses onanalyzing the current system and determining its capability to support the current

and future population as well as the redesign of the sewerage pipe works at

University of Guyana.

2. The pumps at the lift station would not be sized.3. This project does not entail the design and checks for the treatment plant.4. Design does not include branched sewers for new nodes in the sewerage system.

7.0 Assumptions

1. All exiting pipes are four inches (4)in diameter.2. All manholes are fully functioning.3. For ideal conditions the discharge would be 3ft3/sec.4. A mannings n of 0.014 (for P.V.C pipes)will be used.5. No intercepting flows.


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8.0 Literature Review

Bradford (2005) has outlined the design procedure for sanitary sewer design. The

suggested procedure consists of:

1. Determining the design period;2. Identifying the contributing area;3. Estimating the sanitary sewage flow rates;4. Carrying out the hydraulic design and5. Calculating the pipe sizes.

The table below explains the activities involved in each stage of the sanitary sewer design.

Table 1 - Design stages for a sanitary sewerage system

Design Stage Activities Involved

Design Period A suitable design period and the population

growth rate must be selected. The water usage

rate must also be determined.

Contributing Area The boundaries of the network must be defined

and the population within the area determined.

The unit water usage must also be determined.

Flow Rates The sanitary sewage flow and peak flow rates

must be determined.

Hydraulic Design The hydraulic constraints must be identified.

These include: pipe roughness, velocities, depths.

Pipe Sizing Sizes, gradients and depth must be determined.


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8.1 Design Period

The design period is that length of time over which the capacity of the sewerage facility is

anticipated to be adequate to service its contributing area. It must be determined before

design of the facility commences. A standard for minimum design periods for various

components of a sewer system is provided by the Bureau of Engineering (n.d.) and states

that for lateral sewers - sewers less than 18-inch in diameter, the minimum design period

is 100 years.

8.2 Tributary Area

The tributary area of a sewer includes all areas which will contribute flow to the system.

Potential service areas, such as, areas served by septic tanks should also be assessed for

possible inclusion in the contributing area. The area may be limited by natural topography,

natural or human-made barriers, political boundaries or economic factors.

8.3 Determination of Design Flows

The design of sanitary sewers must consider minimum, average, and peak flows. Normally,

the average flow is determined or selected, and a factor is applied to determine the peak

flow. The Peak flow is the design flow used to select the pipe size. Minimum flows are used

to determine if specified velocities can be maintained to prevent deposition of solids. The

Bureau of Engineering (n.d.) states that the ratio of peak flow to average flow will range

from less than 130% for some large sanitary sewers to more that 260% for smaller sewers.

Additionally, the ratio of the peak flow at the end of the design period to the minimum flow

at the beginning of the design period may range from less than 3:1 to more than 20:1,

depending on the rate of growth of the contributing area served.

8.4 Minimum Velocity

According to the Bureau of Engineering (n.d.) gravity sewers shall be designed for a

minimum velocity of three (3) fps using the peak flow that exists at the time the pipe is

placed into service. Approval must be obtained when using slower design velocities. This

minimum velocity is necessary to prevent deposition of solids in the sewer pipe.


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8.5 Types of Flow

The flow of wastewater in sewers may be open channel or pressure flow. When flow fills

the conduit and the Hydraulic Grade Line (HGL) rises above the sewer crown, the flow is

classified as pressure flow. When the conduit is partially full and the HGL is below the

sewer crown and a free water surface develops in the sewer, the flow is classified as an

open channel flow. Open channel flow will be the basis for general hydraulic design of

sanitary sewers.

8.6 Design Criteria

The criterion for design of sewer pipe includes:

1. Type/size sewer line;2. Design period;3. Design depth of flow; and4. Peak flow.

According to the Bureau of Engineering (n.d.) sewers shall be sized so the depth of the

peak flow, projected for the design period, shall be no more than one half the pipe

diameter: d/D = 0.5

Where: d = depth of flow and D = Pipe diameter

8.7 Calculation of Pipe Size

The required pipe size may be calculated using Manning's formula:

=

2//2

Where:

Q = volume flow (ft3/s, m3/s)

kn= 1.486 for English units and kn= 1.0 for SI unitsA = cross sectional area of flow (ft2, m2)

n = Manning coefficient of roughness

R = hydraulic radius (ft, m)

and R = A / P (where: A = cross sectional area of flow (ft2) and P = wetted perimeter (ft))

S = slope of pipe (ft/ft, m/m)


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8.8 Mannings Roughness Coefficient "n"

A Manning's roughness coefficient of "n" = 0.014 shall be used for sizing gravity sewers.

This Manning's roughness coefficient shall be used regardless of the type of pipe specified.

8.9 Minimum SlopeGravity sewers shall be designed for a minimum velocity of three (3) fps using the peak

flow that exists at the time the pipe is placed into service.


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3. Based on past and existing campus population data, the present population growthwas determined.

4. The required flow was determined for each building and was done by establishingthe effluent volume production for each area. The required flow in the sewer is the

maximum flow resulting from the collection of sewage at any point in a system. The

average, peak, and minimum flow must be considered in design. The average flow is

estimated by considering future population, water consumption and the relevant

standards.

5. The design flow of pipes was determined based on the population of each sectionand the volume of effluent that is expected to pass through the pipes.

6. Infiltration and extraneous flow also contribute to flow volume. Peak and minimumflows are determined by applying factors to the average flow. These factors are

generally based on local experience and codes. Peak flow is used to select pipe size

and minimum velocity, taking into consideration peaking factors as well as factor of

safety. A minimum self cleansing velocity of 0.75m/s was considered in the design of

sewers.

7. The hydraulic flow through the sewer system was carried out using the Manningshydraulic flow equations. The equations were used to design sewers to transport

the waste water.

8. From the calculations carried out for the peak flow, and consideration of theminimum self cleansing velocity and maximum flow of the sewer, the pipe size was

determined, considering also the roughness coefficient and the slope of the pipes.

9. The final drawing of the new sewerage system was prepared using AutoCAD. Thesedrawings were done to scale which facilitated the length of sewer lines to be

measured and the quantity of pipelines required for construction was therefore

determined.10.An engineers estimate for the construction of the new sanitary sewer network was

prepared and included the construction of manhole chambers and blanking off from

the existing system and connecting to the new one.


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10.0 Sewer Design

The design criteria adopted for the sanitary sewer design are those acceptable to the

relevant standards. These criteria used to estimate the design flows which will in turn be

utilized in the design of the sewer system are:

i. Design Periodii. Population

iii. Peaking Factoriv. Slope of Sewersv. Hydraulic Loadings

vi. Design

10.1 Design Period

The sewer systems would be designed for an expected life of twenty five (25) years.

10.2 Population

The design flow for each sewer depends on the population of the area being considered. A

population of six thousand (6,000) was used as instructed by the course Lecturer, Mr. M.

Jackson. This is inclusive of students and staff.

10.3 Peaking Factor

A capacity factor is used to make allowances for population variation, changes in sewage

characteristics and unusual peak flows. This factor is also referred to as the peaking factor.

The peaking factor is determined as a function of the population size and is based on the

following formula:


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Qk huQvg

=1 8 + P4 + P

Where:

Qk hu= maximum rate of wastewater flow (peak hourly flow)

Qvg= Design average daily wastewater flow

P= Population

A peaking factor of 3.5 was used for this design.

10.4 Slopes of Sewers

The sewerage has been designed based on Mannings equation and based on the existing

system. The size of the sewers and slopes to be used for design of new sewers are as

follows:

Sewer Minimum Size (mm dia) Minimum Slope (%)

Branch

MainMain

100

150200

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However the existing inverts and length of the sewers would be used to determine the

slopes to check the capacity of the existing system.

10.5 Hydraulic Loadings

The water consumption used in this design is 180 litres per person per day. Of this amount

85 percent was considered to be spent water that will enter the sewer system.

Hydraulic loading per capita = 0.85 180 l/person/day

= 153 l/person/day


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11.0 Sanitary Sewer Flow Calculation

= () + equation (1.1)

Where:

Q = Sanitary Flow

. = Average Sanitary Flow = 0.000063 cfs/capita

P = Population of Tributary Area based on design density

PF = Peak Factor = 3.5

I = Infiltration allowance = 0.003 cfs/acre

A = Tributary Area

The University of Guyana occupies a total area of 1,450 acres of which only 80 acres will be

considered in the design of the sanitary sewer. The additional 1,370 acres is not being

considered since area is undeveloped and covered with natural vegetation. The current

population of the University of Guyana Campus is approximately 6,000 inclusive of

students and staff.

Applying the conditions outlined above in equation (1.1)

= 0.000063/ 60003.5 + 0.003/ 80

= 1.563

= 0.0443

Minimum Velocity to design for is 2ft/sec.


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11.1 Calculation of Pipe Size

After the design criteria have been determined the required pipe size may be calculated

using

Manning's formula.

= .

2//2 equation (1.2)

Where:

Q = Flow, cfs

A = Area of flow, ft2

R = Hydraulic radius (A/P), ft

n = Roughness factor

Rearranging equation 1.2 to solve for diameter of pipe D

D = 1.3346 Q0.375 n0.375

S 0.1875

Where:

D = Conduit inside diameter, ft

Q = Volumetric flow rate, cfs

n = Mannings roughness coefficient

S = Friction slope, ft/ft (minimum slope for pipe is approx. 0.0036 ft/ft)

The manning n used in this design will be taken as 0.014 (P.V.C) since P.V.C pipes will be

used through this design.

D = 1.3346 x1.5630.375 x0.0140.375

0.00360.01875

D = 0.354ft (use 6 inches dia. pipe) (150mm)

Diameter of pipe = 6 inches.Maximum depth of flow d = 2/3D (for 10 inch and smaller)

d = 4 inches

Current diameter of pipe in operation is four inches. (P.V.C)


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11.2 Modelling

Modeling of the sewer system is required when proposed development intensifies. The

land use from the existing development on the site to the proposed development requires

the general plan to be amended to cater for the increased usage. The following three

scenarios must be modeled:

1. Existing Condition to identify existing deficiencies in the system2. Existing Condition with Proposed Development to identify additional

deficiencies created by the proposed development

3. General Plan Build Out Condition to identify the ultimate pipe size forimprovements


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12.2 Quantities

Even though practical care was exercised in preparing the BOQ, all quantities given herein

shall be deemed to be estimated quantities of the work to be done but they are not to be

taken as actual and correct quantities of the work to be executed and they are not to

absolve the contractor of his obligations under the Contract. They are not to be taken as

guarantee that the actual quantities increase or decrease, and any claim whatsoever

submitted for cost or extra expenses incurred from such increase or decrease will not be

accepted by Employer/Engineer except where else stipulated in the Contract.

12.3 Materials

All materials used are to be of the best quality, available and will be subjected to the

Employer/Engineer approval, and of durable nature, guaranteed, not liable to any base

exchange and manufactured according to applicable BS or ASTM Standards. Execution also

is subject to approval of Employer/Engineer and shall be the best available common

practice in engineering codes at the time of execution.

Items that contain materials or products of special make with names of manufacturers are

to be taken as samples of what will be required. Subject to the Employer/Engineer

approval, the Contractor may, at his discretion, offer similar products of other make if the

equivalent quality of the specified materials is guaranteed. In this case, the Contractor shall

submit a description and/or drawings showing all technical conditions, characteristics,

make, type and address of Manufacturer, etc., of the materials offered as alternatives.


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12.4 Prices and Currency

The prices given, by the Contract, hereunder in the BOQ shall be in Guyana Dollars (G$)

and shall not be exchangeable with other foreign currencies. Furthermore inflation and

escalation or changes whatsoever shall not be subject covered by the Employer unless they

are responsible for any prolonged delay in the execution of the works.

The Unit Prices entered against the various items in the following Bill of Quantities include

all operations for execution, and completion of the various items of the works finished

completely in every respect till the final acceptance as specified or described in the Tender

Documents, with or without modifications, either by way of additions or deductions, or

alterations as may be offered in writing during the progress of the works, and include,

without being limited to, all matters and things particularly referred to in the Tender

Documents.

The Unit Price shall cover all costs of every kind whatsoever including, without being

limited to, all charges for additional site installations, relocation, supervision, labor,

transportation and supply of materials; the provision, maintenance, use and efficient repair

of all plant, equipment and appliance of every kind, the construction and maintenance of all

temporary works, the performance of all services and the fulfillment of all obligations and

responsibilities herein defined.

The Tenderer shall be deemed to have fully considered all the conditions, obligations, and

requirements of the Tender Documents before entering the respective unit price against

the various items of the Bill of Quantities.

The Unit Prices given hereunder the BOQ shall also include construction, installation, fixing,

and re-fixing of all elements. These prices shall also include taxes, accommodations for the

Contractors staff and labors, all required insurance and work permits, guarantees, bonds,

traffic plan requirements, safety procedures, etc. and all requirements necessary to have

the work maintained until its final handing over.


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The Unit Prices given hereunder in the Bill of Quantity for this work shall also include

overheads, risks, profit etc. and all other financial matters to have all these civil works

completed.

The works, materials or activities listed in the following shall always be considered as

Supportive works to be included in the Unit Prices bid for any item in the Bill of Quantities:

Any measurement for execution and payment of the works, including the provisionof measuring instruments, gauges, setting out marks, marking paint and relevant

tools, labor, etc., the maintenance and preservation of gauges and setting-out marks

during the execution of the works.

Provision of small tackle tools or any other equipment required for the execution ofthe works.

Supply of consumable materials for the Contractors equipment. Removal of all contamination (refuse, debris, building rubbish and the like) arising

from or in connection with the Contractors work.

Protection of the executed works and of the items made available for execution ofthe works from damage, fire, inclement weather, vandalism and theft etc., to the

time of final acceptance.

Transportation of all materials and structural components from the storage placeson site to the points of use and return transportation, if required.

Submitting and transporting any samples required. Carrying out tests on materials and works, etc., that is required by the Engineer. Fuel and lubricants for operation of Contractors equipment. All safety precautions and measures for safeguarding labor as well as securing

surrounding areas.

Lighting of the work site. Maintenance or repair damaged infrastructure resulted by contractors activities


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various unit prices of the Bill of Quantity. No extra payment will be allowed by the

Employer for any of these activities.

12.8 Duration

The total duration of the contract is six calendar months including weekends, holidays

and official holidays.


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13.0 Priced Bill of Quantity


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14.0 Recommendations

1. New manholes should be constructed; the new design should cater fordiverting the current sewer lines (which have been sealed and currently

cannot be accessed or serviced) to the new manholes which will flow to the

collector system and then main disposal system. This would also enable the

sewer system to be adequately maintained.

2. Skilled personnel should be hired to examine the mechanical appurtenancesfor the jet to reinstate the current system to its initial fully automated state.

3. Due to the increase in flow due and the increase utilization of the sewersystem the sizing of the sewer diameter should be revised.

4. All broken and damaged sewer pipes should be replaced.


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15.0 Conclusion

The existing sewer system is inadequate to cater for the projected population growth of the

entire campus for the design period. A drawing and design are outlined for the rerouting of

a new sewer system to serve the needs of the University of Guyana, Turkeyen Campus.

The existing system has the following deficiencies:

1. There are a series of non-functioning manholes due to the rapid increase in thecampus population and inability of the university to provide sufficient classroom

and office space for students and staff. This has resulted in manholes that run below

buildings being sealed off to provide the additional space required.

2. The fully automated system of the pumps is not functioning; this resulted in a semi-automated operation.

3. The current system is inefficient since current student population exceeds the initialdesign capacity.

4. Inadequate pipe sizing also hinders the efficiency of the current system since arecent redesign was not done to offset the exiting discharge.

5. According to the calculations it was also revealed that the optimum sewer diameternecessary for an efficient flow was 6 inches; however this is for the current

population and thus will become efficient with growth in the student population.


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16.0 References

1. Bradford, Andrea. (2005). Sanitary Sewer Design Tutorial: Urban Water Design 437.Retrieved November 27, 2010, from

http://www.hydrolatinamerica.org/jahia/webdav/site/hydrolatinamerica/shared/

Reference/Sanitary%20Sewer%20Design.pdf

2. Bureau of Engineering (n.d.). Sewer Design Manual - Part F. Retrieved November 27,2010, from http://eng.lacity.org/techdocs/sewer-ma/index.htm

3. Sanitary Sewer Design Guidelines, Engineering Design& ROW Management DivisionNovember 2004.
http://www.hydrolatinamerica.org/jahia/webdav/site/hydrolatinamerica/shared/http://eng.lacity.org/techdocs/sewer-ma/index.htmhttp://eng.lacity.org/techdocs/sewer-ma/index.htmhttp://www.hydrolatinamerica.org/jahia/webdav/site/hydrolatinamerica/shared/


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Photo showing: A existing manhole (Technology Sport Club) Photo showing: A sealed manhole within a building

(Taken by: Kalvika Singh on the 12th-10-2010) (Technology Lab)