RECOMMENDATIONS
FROM
VALUE ENGINEERING STUDIES
ON
WASTEWATER TREATMENT WORKS
Robert B. Williams
Robert G. Gumerman
William R. Whittenberg
Nancy E. Heim
Culp/Wesner/Culp - Clean Water Consultants
El 'Dorado Hills, California
Santa Ana, California
Contract No. 68-01-5938
Project Officer
Haig Farmer
Municipal- Construction Division
Office of Water Program Operation
United States Environmental Protection Agency
Washington, D.C. 20460
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DISCLAIMER
This report has been reviewed by the Municipal Construction Division, U.S.
Environmental Protection Agency, and approved for publication. Approval does not
signify that the contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
NOTES
To order this publication, "Recommendation from Value Engineering Studies or
Wastewater Treatment Works" (MCD-69) from EPA, write to;
General Services Administration (8FFS)
Centralized Mailing List Services
Building 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the MCD number and title of publication.
Multiple copies may be purchased from;
National Technical Information Service
Springfield, Virginia 22151
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ABSTRACT
This publication summarizes the best ideas/recommendations from 93 value
engineering (VE) reports which were completed under EPA's mandatory VE program
for 75 construction grant projects. Data abstracted from these reports provided
the basis for an overall evaluation of the VE program. Application of VE ideas/
recommendations and evaluation results presented in this publication should
enhance the effectiveness of VE in the design of future wastewater treatment
facilities.
ii
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FORWARD
Since the mandatory value engineering (VE) program was' initiated in October
1976, it has produced substantial construction cost savings and a high rate of
return for the VE investment. The program has saved an average. of 5.1 percent of
the construction costs on projects which required VE studies. Stated another way,
the VE program has achieved a $12 return for each dollar invested in VE costs.
This publication represents the Environmental Protection Agency's (EPA) con-
tinuing efforts to evaluate and improve the effectiveness, of the VE program. The
publication summarizes the best ideas/recommendations from 93 VE reports com-
pleted under EPA's mandatory program and presents general information for improv-
ing the future performance of the program. .
This publication does not present any regulatory requirements. The require-
ments and guidance for conducting VE studies on EPA funded projects are contained
in Section 35.926 of the Construction Grants Regulations, the Value Engineering
Workbook (MCD-29) published in July 1976, and the Value Engineering Case Studies
and Formats For Proposals and Reports published in June 1977.
This publication is designed to serve as a reference source.for wastewater
treatment design engineers and VE study teams in their efforts to improve the
quality of future treatment facilities while minimizing the construction and
operational costs.
The Environmental Protection Agency intends to continually evaluate and
improve the VE program. Therefore, all users of this publication are encouraged
to submit any pertinent information on the VE program to the Director, Municipal
Construction Division (WH-547), Office of Water Program Operations, U.S.
Environmental Protection Agency, Washington, D.C. 20460.
Eckardt .C. Beck
Assistant Administrator for
Water and Waste Management (WH-556)
111
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TABLE OF CONTENTS
Disclaimer
Notes
Abstract
Forward
Chapter 1 - Introduction
Background
Purpose and Scope
Description of VE Studies
Criteria Used for Selection of VE Recommendations
Recommendations on Conducting VE Studies
Chapter 2 - Basins and Tanks
Shape
Size
Materials
Design Concepts
Chapter 3 - Process Equipment
Flow Equalization
Pumps - Influent and Effluent
Pumps - Process
Flow Measurement
Screening
Grit Removal
Clarifiers
Trickling Filters
Aeration System (Including Pure Oxygen)
Disinfection
Filtration
Post Aeration
Chemical Feed
Sludge Collection
Sludge Thickening
Sludge Dewatering
Sludge Stabilization
Sludge Disposal
Chapter 4 - Site Layout (Plant and Equipment)
Earthwork
Roads
Piping
Equipment and Process Layout
Hydraulics and Hydraulic Gradeline
Miscellaneous
Chapter 5 - Buildings or Structures
Size ,
Location
Materials
Floor Plans
Type of Construction
Appurtances
1
1
2
2
4
5
7
7
13
14
15
23
23
27
33
43
44
45
49
52
53
65
68
70
71
73
74
78
82
87
89
89
92
94
107
113
116
117
117
119
123
124
127
136
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TABLE OF CONTENTS (Continued)
Chapter 6 - Electrical, HVAC and Controls
Power Distribution
Instrumentation
Control
Lighting.
HVAC
Chapter 7 - Energy
On-Site Generation ,
Heat Recovery
Conservation ,
Chapter ,8 - Aesthetics
Odor Control
Noise Control
Architectural
Chapter 9 - Constructability
Structural Details '''...: , .
Construction Sequencing .
Materials
Chapter 11 - Sewers ., - .
Manholes
General Construction
Chapter 12 - Interceptor System Pumping Stations . . ...
Structure
Emergency Generator
Piping ; ;
Design Concepts
Chapter 13 - Ocean Outfall
Covering Material :
Construction Material , .
Construction Technique , .
Design Concept , .
Appendix A - Value Engineering Program Evaluation^ .
Productivity of VE Teams
Potential VE Savings ,
Acceptance of VE Recommendations
Identification of High Cost Components
Composition of VE Teams
Cost and Level of Effort for VE Studies
Reasons for Rejection of VE Recommendations
General Observations .
Appendix B - Ideas Applicable to Most Wastewater Treatment Projects
Design Criteria
Site Work and Layout
Site Buildings
Structural
Equipment ,
Mechanical ~ .'...
Page
137
137
142
146
150.
151
153
153
154
156
159
159
166
164
167
167
170
171
175
175
176
177
177
178
179
181
182
182
185
186
187
A-1
A-1
A-2
A-6
A-11
A-13
A-14
A-18
- A-19
B-1
B-1
B-2
B-3
B-4
B-4
B-5
V
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TABLE OF CONTENTS (Continued)
Page
Appendix B - Ideas Applicable to Most Wastewater Treatment Projects (cont.)
Electrical and ISC B-5
Energy Conservation B-6
Miscellaneous B-7
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LIST OF TABLES
1 ' RESULTS OF VALUE ENGINEERING PROGRAM
2 DISTRIBUTION OF VALUE ENGINEERING REPORTS
3 TREATMENT UNITS AND MISCELLANEOUS FACILITIES
EVALUATED IN VE PROGRAMS
4 DISTRIBUTION AND STORAGE OF DESIGN COMPLETION OF WORKSHOPS
Page
1
2
3
4
vii
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LIST OF FIGURES
Page
1 Change wye wall to tee wall. 8
2 Reduce length of dividing walls. 10
3 Square clarifiers instead of circular. 11
4 Square clarifiers instead of rectangular. 12
5 Common wall construction between chlorination and post aeration. 17
6 Simplify chlorine contact tank valving. 18
7 Use outboard launders. 19
8 Substitute earthern basin for concrete basin. 25
9 Revise inlet to pumping station. 28
10 Right angle drive system. 29
11 Vertical turbine pumps. < 34
12 Combine pumping stations. 36
13 Pump primary effluent directly to bio-filters. 37
14 Use mixed flow pumps in lieu of screw pumps. 39
15 Use vertical mixed flow pumps. 40
16 Use vertical mixed flow pumps instead of screw pumps. 41
17 Exchange grit channels for Pista grit chambers. 46
18 Simplify grit removal. 48
19 Replace primary effluent channel with pipe. 50
20 Replace low pressure air scum control system with
collection mechanism. 51
21 Emergency drive for pure oxygen air compressor system. 54
22 Use dual drives for blowers. 56
23 Replace swing drop pipes with lift out drop pipes. 58
24 Use complete mix activated sludge. 61
25 Replace mixed liquor channel with pipe. 63
26 Replace control valves with telescoping valves. 76
27 Use precast concrete walls. 80
28 Design sludge drying beds for mechanical equipment. 81
29 Mechanical mixing in anaerobic digesters. 83
30 Replace retaining wall with precast panels in H-piles. 91
31 Simplify return activated sludge flow balancing scheme. 95
32 Reduce length of yard piping. 98
33 Delete drain pipes and gates from head end of aeration basin. 100
34 Relocate flow splitter box. 101
35 Simplify mixed liquor piping. 102
36 Use single mixed liquor pipe to secondary clarifiers. 105
37 Simplify scum handling system. 106
38 Scrubber water recycle streams. 108
39 Modular design of unit processes. ' 110
40 Relocate odor scrubber outside building. 112
41 Raise influent screw pumps. 115
42 Eliminate sludge conveyors. 120
43 Simplify gravity sludge thickening system. 122
44 Use reinforced concrete pipe for tunnels. 129
45 Use insulated steel siding for buildings. 131
46 Substitute acoustic metal panel for "Sound Blox". 132
47 Use fiberglass covers over tertiary filters. 133
viii
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LIST OF FIGURES (continued)
48 Dissolved oxygen control system.
49 Reduce size of main control room.
50 Install heat exchangers on effluent sludge line.
51 Extended pump discharge pipe below water surface.
52 Use two-stage carbon for odor control.
53 Wall strut system.
54 Use steel framing.
55 Use "Shotcrete" fixed cover on anaerobic digester.
56 Use force main instead of gravity interceptor.
Page
145
147
155
157
161
168
172
174
180
IX
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CHAPTER 1
INTRODUCTION
BACKGROUND
Value Engineering (VE) was first introduced into the EPA Construction Grant
Program on a voluntary basis in 1974 based on the success of this cost control
technique in other Federal agencies. VE was described as a "systematic and crea-
tive approach to identify unnecessarily high costs in a project in order to
arrive at a cost savings without sacrificing the reliability or efficiency of the
project or increasing operating and, maintenance costs." The success of the volun-
tary program was measured in terms of the following:
ซ Effective in cbjst control
ซป Substantial cost savings achieved , . . .-
9 Project delays can be avoided
0 Quality and reliability maintained
9 Provides for more efficient and better design techniques.
This success prompted the EPA to institute the mandatory VE program in 1976
which required all projects with a total estimated^construction cost (excluding
the cost -of sewers) of $10 million or :greater to have value engineering. Projects
with lower estimated construction costs still are encouraged to participate in
the VE program on a voluntary basis. , - . :
The summary results of the voluntary program and the mandatory program for
fiscal years 1977, 1978 and 1979 are, presented.in Table 1. This table clearly,
shows that the mandatory VE program has been successful when measured in terms of
the net savings. The program has realized an average savings of 5 percent in
project costs and a net capital savings to VE costs ratio of more than 12 to 1.
RESULTS OF VALUE ENGINEERING PROGRAM
Fiscal
year
Pre-19772
1977
1978
1979
--'-
No .of VE
projects
8
28
28
31
Total
capital
project costs
$1,000's
450,000
1,426,700
501,807
807,220
VE costs^
$1,000's
700
6,354
1,660
3,287
Net.VE
capital
savings
$1,000's
18,000
73,604
21,871
45,182
Net
savings
%
4.0
5.2
4.4
5.6
Savings
cost ratio
25.7:1
11.6:1
13.2:1
13.8:1
1Includes VE fee and implementation costs
2Voluntary program
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PURPOSE AND SCOPE
The purpose of this publication is to present a reference document of the
most* worthwhile ideas or recommendations from 93 Value Engineering reports pre-
pared for 75 projects under EPA's mandatory VE program. This publication is
intended for use by design engineers and future VE teams as a "memory jogger,"
either for specific ideas or to stimulate alternative suggestions and ideas.
A secondary benefit of examinating such a large spectrum of VE studies was
the opportunity to conduct a general evaluation of the VE program. This evalua-
tion should provide an excellent basis for improving the effectiveness of future
VE studies. The details of the evaluation are presented in Appendix A.
DESCRIPTION OP VE STUDIES
All of the VE studies were conducted on "mechanical" wastewater treatment
facilities, pumping systems, sewers, outfall systems. A VE analysis of a land
application system has not yet been conducted under the mandatory VE program. The
capacity of the wastewater treatment facilities studied in the VE program ranged
from 1 mgd to 160 mgd average daily flow, as shown in more detail on Table 2. The
estimated pre-VE construction costs ranged from about $3 million to $250
million.
TABLE 2. DISTRIBUTION OF VALUE ENGINEERING REPORTS
EPA
Region
1
2
3
4
5
6
7
8
9
10
Number of
projects Treatment plant size
evaluated < 1 MGD
6
5
4
17
14
2
3
2
17
5
1-10 MGD
_
2
1
1
1
1
1
-
3
3
10-50 MGD
6(5)1
1
3
16(6)
9(6)
1
1
2
6(1)
2
Sewer
>50 MGD Outfall or P.S.
_
1 1
_ _ _
- _ _
2(2) - 2
_ _ _
1
_ _ _
4-4
-
Total
75
13
47(18)
6(2) 1
lumber in parenthesis designates number which include AWT.
The wastewater treatment and solids handling process and miscellaneous
facilities included in the VE studies are presented in Table 3. This shows the
large variety of treatment processes that have been evaluated over the past few
years under the mandatory VE program. By far the majority of the wastewater
treatment plants were activated sludge systems designed to produce better than
secondary effluent quality, typically 20 mg/L BOD5 and 20 mg/L suspended solids
or better. Solids handling generally centered around waste activated sludge
thickening, anaerobic digestion, sludge dewatering and landfill of the stabilized
residue.
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TABLE 3. TREATMENT UNITS AND ^MISCELLANEOUS FACILITIES
EVALUATED IN VE PROGRAMS .
Wastewater treatment
Solids handling
Mi s ce1laneous
facilities
Flow equalization
Flow measurement
Screening
Grit removal
' Aerated ' .
V Constant head
Constant velocity
Pre-aeration
Influent pumping
Electric driven
Engine driven
Primary sedimentation
Biological treatment
Activated sludge
Trickling filter
Rotating biological
Contactor
Pure oxygen
Secondary sedimentation
RAS pumping
Effluent filtration
Disinfection
Chlorine
Ozone
Dechlorination
Nitrification
Phosphorus
Chemical addition
PhoStrip
Raw sludge pumping
Gravity thickening
WAS pumping
WAS thickening
Dissolved air
/flotation
ซ Centrifuge
Belt press
Sludge stabilization
Anaerobic digestion
/ Aerobic digestion
Lime addition
Sludge dewatering
Vacuum filtration
Belt press
Centrifuge :
Pressure filtration
Sludge conditioning
Heat treatment
ป Chemical addition
, Incineration
Land disposal
Liquid
Dewatered
Transport . :
Pipe
Truck
Odor control :
Chemical .; ,
Activated Carbon
Organic removal
tower . ,
Garage/shop bldgs.
Administration bldgs.
Site configuration
Facility locations
Roads
Landscape ...
Construction Methods/
Materials
Control Systems
Computer
Analog
Manual ... .
Electrical systems
HVAC
Yard piping-
Fencing
Site lighting
The scope of the VE studies did not show any consistent pattern related to
project size or complexity. The majority of the VE projects consisted of only a
single workshop with a single team. Many .projects had two workshops and rela-
tively few projects were subjected to three or more workshops. In general,
multiple teams were provided by large design firms and single teams by small
firms. ,
The timing of the workshops is a critical element of a successful program,
especially for projects with a single workshop. The early workshops offer the
greater potential for savings even though details of construction or equipment
selection cannot be evaluated at this stage. The later workshops offer lower
potentials for savings because recommended changes are of smaller magnitude since
the study emphasis is on process equipment arid constructability of the project. A
majority of the VE reports evaluated were held early in the design stage as shown
in more detail in Table 4.
3
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TABLE 4. DISTRIBUTION AND STAGE OP DESIGN COMPLETION OF WORKSHOPS
EPA
Region
1
2
3
4
5
6
7
8
9
10
Total
Percent
Number of
projects
evaluated
6
5
4
17
14
2
3
2
17
5
75
"
Number of
workshops
held
10
6
5
17
17
2
3
3
22
8
93
^
Stage of design completion of
<20%
0
2
-
1
2
-
-
-
2
1
8
8.6
20-40%
5
-
4
8
10
1
3
2
12
2
47
50.5
40-60%
4
3
-
6
3
1
-
1
7
1
26
28.0
60-80%
1
-
1
2
2
-
-
-
1
3
10
10.8
workshop
80-100%
-
1
-
-
-
-
-
-
-
1
2
2.1
CRITERIA USED FOR SELECTION OF VE RECOMMENDATIONS
The enormous number of individual recommendations from 75 VE projects
required a selection system to reduce the number of ideas to a manageable level.
The criteria used in the selection systeme are listed below:
Estimated savings - Initial and life cycle costs
Reliability
Widespread applicability
Technical validity
Minimization of overlap between projects (same idea not evaluated for
more than one project)
A minimum of 1 idea from electrical and architectural disciplines per
VE contract (where possible)
Only the first and last criteria represent an absolute selection. The latter
item was included in order to include at least a certain number of ideas in areas
where the savings have been small in terms of absolute dollars, at least relative
to the potential savings associated with equipment or concrete changes. The other
criteria were included to eliminate "one-of-a-kind" recommendations that may have
saved a great amount of money on one project but which are not widely applicable.
These criteria were an aid to selecting the best 10 to 15 ideas (if possible)
from each workshop out of a total in the range of 5 to 60 ideas. In the first
instance, as few as 1 or 2 have been included, but in the latter instance maybe
as many as 20 were included. The intent was to present a representative sampling
of ideas from each VE project, yet not to present the same idea more than once.
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RECOMMENDATIONS ON CONDUCTING VE STUDIES
The VE reports examined for this publication clearly demonstrated that many
positive benefits can be achieved from the use of VE studies. VE serves as a
mechanism to enhance the design of wastewater treatment facilities by providing
the project designer with an opportunity to utilize the knowledge and experience
of other individuals to optimize the project design. ,
The review of the VE reports, as well as interviews and discussions with
various EPA Regional VE Coordinators, State personnel, and firms experienced in
conducting VE studies, formed the basis for the following recommendations.
Appendix A of; this publication contains detailed discussions of the data used to
formulate some of thes recommendations. ,,..'
* VE teams should closely follow the format for, VE reports presented in
the EPA Manual on,"Case Studies and Formats", MCD 27. Such standardiza-
tion of the VE reports will facilitate review and approval of the
reports. .-' -.--,.,... ..-,-.- . : . , ,
The number of firms represented on a VE team should be minimized to
improve the team's productivity. VE teams that include more than one
consultant firm tend to be less creative than VE teams from a single
firm. :"''''" . , ...
' ซ It is advantageous to the designer and owner not to use individuals
from the designer's firm on the VE team, since VE teams not related to
the designer's firm provide greater originality, creativity, and oppor-
tunity for cost savings. However, in the instances where the team must
use personnel from the designer's firm, the team coordinator and at
least two other members should be from another firm.
e VE teams should recommend only those ideas that they would implement on
their own designs. This approach would eliminate the tendency to recom-
mend unproven ideas.
e Each VE recommendation should include only a single "idea. Several ideas
in a recommendation may result in many good ideas being discarded due
to the rejection of one idea in the recommendation. -.---
ป The VE teams should spend sufficient time on each recommendation to
carefully and thoroughly develop it. The recommendations should include
all assumptions and computations for capital, operating, and mainte-
nance costs. Each recommendation should be clearly and concisely pre-
sented in the VE report.
o VE team members should have attended a 40 hour VE training workshop.
However, this training should not be a rigid prerequisite for team mem-
bership since the success of a VE study is ultimately dependent on .the
pertinent experience of individual team members.
ซ VE teams should include at least two sanitary engineers since this
engineering discipline normally has principal control of over 70
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percent of the construction costs of a project. Two sanitary
engineering team members will enhance the opportunity for interaction
and creativity during the VE study.
If only one VE study is scheduled for a project, it should be conducted
during the 20 to 30 percent design stage to obtain maximum benefits
from the study.
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BASINS & TANKS
Shape
CHAPTER 2 _^_
BASINS AND TANKS
SHAPE
Replace Circular Final Clarifiers with Rectangular Clarifi'ers
The original concept proposed three 100-foot diameter final clarifiers, with
a fourth clarifier to be added in the future. The sludge collection equip-
ment was center column support, rapid removal type.
The proposed concept would use rectangular final clarifiers with traveling
: bridge suction sludge collectors. The tanks would be constructed with a
common wall to the aeration tanks and contain channels for influent distri-
bution, sludge collection, and effluent channels. -.'.---.
Fewer Passes in Chlorine Contact Chamber
A baffled chlorine contact tank was designed with four baffles, which pro-
duced five passes through the tank. The thickness of the interior baffling
walls was,the same as the exterior walls of the contact tank.
Use of three passes was recommended which eliminated two of the baffling
walls. The thickness of the baffling walls was also reduced.
Reduce Depth of Equalization Basin
A flow equalization basin was designed with a depth of 25. feet.
Because of difficult subsurface conditions, a shallower depth basin with an
equivalent volume resulted in a lower initial cost. A basin with a depth of
16 feet was recommended.
Change Aeration Basin Side Walls from Wye Wall to Tee Wall
Originally, the aeration basin side walls were designed with a wye config-
uration at the top, and with the main air header located in the wye. Alumi-
num access plates were used over the Wye opening.
The proposed concept used tee walls, with the main air header hung under the
head of the tee on one side. This main header supplied air for the basins on
each side of the wall. Sketches of the original and proposed concepts are
shown in Figure 1.
Rearrange Basins to Reduce Length of Dividing Wall
The original design of the flow equalization basins involved the use of four
separate, parallel basins. Each basin had separate feed and withdrawal pip-
ing. The walls were sheet pile dividers with walkways on top.
v*-
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BASINS & TANKS
Shape
AIR HEADER
ซ .
^^f
ORIGINAL CONCEPT
V7-7 ^
AIR HEADER
PROPOSED CONCEPT
Figure 1. Change wye wall to tee wall.
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BASINS & TANKS
Shape
The proposed concept recommended that* the four basins be arranged into a
square configuration using sheet pile wills. The basin would intersect in
the center of the square shape where a distribution structure would distri-
bute and collect the flow and also house the sump pumps. Vehicular access to
this point would be accomplished by using a dike substituting for one sheet
pile wall and protruding to the center of the basin. The recommendation also
eliminated 1000 feet of sheet pile from the original design. Original, and
proposed concepts are shown in Figure 2. _
Change Circular Clarifiers to Square Clarifiers ,
The original design for the primary and secondary clarifiers was circular
with circular sludge collection mechanisms.
The proposed concept used square shaped basins with circular sludge collec-
tion mechanisms. The basins were constructed with common wall construction,
also allowing equipment and pipe galleries for easier access for operation
and maintenance. Sketches of the original and proposed system are shown in
Figure 3. ; ,
Change Rectangular Clarifiers to Square Clarifiers
The initial design included rectangular primary clarifiers with flight and
chain sludge collection mechanisms. Scum removal was by low pressure air
through directional headers.
The proposed design suggested the use of square primary clarifiers with
common wall construction. A gallery between the clarifiers doubles as the
raw sludge pumping station and a pipe .chase. A sketch of the original and
the proposed design is shown in Figure 4.
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BASINS & TANKS
Shape
FEED, PIPE
ORIGINAL CONCEPT
FEED/WITHDRAW
PIPE
ACCESS ROAD
K
>
s
Y
V
T
->
. x SHEET PILE
S DIVIDERS
^
~S
T
PROPOSED CONCEPT
Figure 2. Reduce length of dividing walls.
-\
Y /
1
^DISTRIBUTION
STRUCTURE
^
V
10
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BASINS &. TANKS
Shape -.-".'
PRIMARY
CLARIFIERS
SECONDARY
CLARIFIERS
RAW SLUDGE
PUMPING STATION
RAS & WAS
PUMPING STATION
ORIGINAL CONCEPT
PRIMARY
CLARIFIERS
ACCESS AND
SECONDARY
CLARIFIERS
INFLUENT
3ALLERY.
TV
\
V
/ rit-c. i3Mi_i_cni ?
\
\
^ \ AERATION
1
BASINS
/^X
ACCESS AND
RAIN SLUDGE
PUMPING STATION
PIPE GALLERY, ACCESS AND
RAS & WAS PUMPING STATION
PROPOSED CONCEPT
Figure 3. Square clarifiers-instead of circular,.
11..
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BASINS & TANKS
Shape
PRIMARY CLARIFIERS
RAW SEWAGE /
EFFLUENT CHANNEL
AERATION BASINS -j SECONDARY CLARIFIERS^
'
J /
f-
-L-
J
4-
x
X
/
PIPE GALLERY
ORIGINAL CONCEPT
RAS PUMPING STATION
AND PIPE GALLERY WITH
DISTRIBUTION CHANNEL ABOVE
AERATION BASINS
PRIMARY CLARIFIERS
7
RAW SLUDGE PUMPING
STATION & PIPE GALLERY
c
SECONDARY CLARIFIERS
PROPOSED CONCEPT
Figure 4. Square clarifiers instead of rectangular.
12
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BASINS & TANKS
Size
SIZE .
Reduce the Diameter and Depth of Primary Clarifiers ,
The original design concept used three .130'. diameter circular clarifiers.
Clarifiers were center fed, center well units with two scraper arms and each
was equipped with a scum skimmer. The surface loading rate for the original
clarifiers was 577 gpd/ft^. ,
In the proposed concept the surface overflow rate would increase to 800
gpd/ft2, which would reduce the clarifier diameter from 130' to 117' and
the depth from 12' to 10'.
Reduce the Number of Intermediate Clarifiers
The original concept specified use of four circular 140' diameter center
well clarifiers. ' *
In the proposed concept, the original surface loading rate and solids load-
ing rate would be retained, but the number of clarifiers would be reduced to
three by increasing the clarifier diameter from 140' to 162'.
Reduce Final Clarifier Depth
In the original concept the sidewater depth of the final clarifiers was 12
feet. Sludge was to be removed using rapid sludge removal equipment.
The proposed concept decreased the final clarifier depth by two feet. With
the rapid sludge removal equipment in the tanks, the sidewater depth could
be reduced to 10 feet without loss of removal efficiency.
Enlarge the Clarifiers to Eliminate Need for Filters
The original design proposed construction of four 100 foot diameter clari-
fiers followed by effluent filters for additional suspended solids removal.
The proposed concept recommended constructing rectangular clarifiers with an
overall 32% increase in the volume. This increase would be sufficient to
improve suspended solids removal to a level which would . eliminate the need
for effluent filtration.
13
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BASINS & TANKS
Materials
MATERIALS
Replace Structural Steel Framework with Precast Concrete TEE Sections
Three large diameter trickling filters were to be constructed with an outer
structural wall consisting of corrugated steel sheets supported by a cor-ten
steel framework.
It was proposed that prestressed concrete TEE sections be utilized as a
substitute wall material. To assure a waterproof seal, a membrane liner was
proposed.
Change Material for Sluice Gates
Originally, sluice gates were designed to be constructed from cast iron,
with either bronze or stainless steel trim.
Heavy duty aluminum sluice gates trimmed with polyethelene were proposed.
Stainless steel stems with crank operation were also recommended.
Change Basin Liner from Permeable Asphalt to Gunnite
Flow equalization basins were to be constructed using an earth structure
concept with a permeable asphalt coating. This method of construction
required an expensive sub-base, which was planned to consist of a 4" AC
pavement on a 20" aggregate base.
The proposed concept recommended using reinforced gunnite in place of the
asphalt liner. The recommended plan involved the use of 3" thick gunnite
application with 4" by 4" wire mesh and a 4" thick aggregate base. Although
the gunnite would not be able to withstand vehicular traffic, vehicular
access to the bottom of the basin* was not considered necessary in this
case.
14
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BASINS & TANKS
Design Concepts
DESIGN CONCEPTS
V..K- ' 3^>- " '
Use Cover Over Grit Channel to Replace Handrails
Aluminum handrails were planned for use around grit removal channels.
Use of fiberglass panels over the grit channels were recommended instead of
handrails* According to OSHA requirements/ if such covers are used, they
must be in the down position at all times unless they are attended.
Eliminate Center Walkways
In the original design, each aeration basin center wall was'equipped with a
walkway and spray' nozzles for'foam control.
It was recommended that the walkway, spray header, and nozzles be' eliminated
from the center or intermediate walls.
Construct 3 Circular Secondary Clarifiers Instead of 4
The plant to be constructed utilized two-stage biological treatment, modi-
fied aeration activated sludge for the first stage' "and suspended growth
nitrification for the 2nd stage. Rectangular intermediate clarifiers were
used after the 1st stage, arid 4-115' diameter clarifiers were recommended
after the 2nd stage nitrification. ~
The proposed concept recommended the construction of 3-160* diameter clari-
fiers . This change would result in approximately the same overflow rate, but
the cost would be considerably less for 3 clarifiers than for 4 clarifiers.
Although higher overflow rates would occur with one clarifier out of ser-
vice, this was judged to. be acceptable because effluent storage lagoons were
available for use in emergency conditions.
Above Grade Storage for Backwash and Pumped Backwash --
The original design of the filtration system included provisions for back-
washing the filters using gravity flow, and then collecting the backwash
water in a sump under the filter control building.
The proposed concept recommendated using pumped backwash from an at-grade
storage tank. This alternative allowed the filters and the underground back-
wash water sump to be raised to ground level.
Use the Interceptor Volume as Part of the Flow Equalization Basin Storage
The original concept called for a major flow equalization basin structure to
retain stormwater flows to the treatment plant. Flow was to be diverted from
the interceptor to this structure when the treatment capacity of the plant
was exceeded.
15
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BASINS & TANKS
Design Concepts
The proposed concept recommended using storage capacity in the interceptor
tributary to the plant, with a resultant reduction in the required capacity
of the flow equalization basin.
Combine Chlorine Contact With Post Aeration
The original design provided separate chlorination basin, cascade aeration
and post aeration tank followed by dechlorination (SO2) and pH adjustment
(NaOH).
The proposed alternative eliminated the intermediate cascade aerator. The
size of the chlorination tank remained the same, although the post aeration
tank required enlargement. Common wall construction between the chlorination
basin and the post aeration tank was proposed. The larger post aeration tank
provided increased contact time, increased post aeration and reduced SO2
and NaOH requirements.
concepts.
Figure 5 shows sketches of the original and proposed
Use Outfall as Chlorine Contact Basin
A chlorine contact chamber was included in the original plant design prior
to the outfall.
Elimination of the chlorine contact chamber was proposed, with the required
chlorine contact time being accomplished in the outfall. This concept was
feasible because the outfall provided an overall detention time which
exceeded the detention time in the planned chlorine contact chamber.
Simplify Chlorine Contact Chamber Valving
A chlorine contact chamber was designed to operate using serpentine flow
through five channels. Each channel was designed with the capability of
being fully isolated from the other channels, which would allow any channel
to be taken out of service for cleaning.
Division of the chlorine contact chamber into 2 separate compartments, each
with a five pass serpentine flow was proposed. This approach would allow
either half of the contact chamber to be taken out of service, without dis-
turbing the other half. Redwood dividers were proposed for baffling, instead
of the concrete baffle walls in the original design. Sketches of the origi-
nal and proposed concepts are shown in Figure 6.
Eliminate Inboard Launder on Secondary Clarifier
The initial design concept utilized 80' diameter clarifiers with a double
inboard launder.
The proposed concept recommended eliminating the inboard launders and using
outboard launders. Sketches of the proposed and original concepts are shown
in Figure 7.
16
-------
BASINS & TANKS
Design Concepts
CHLORINATION
CASCADE
POST AERATION
ORIGINAL CONCEPT
CHLORINATION
-." \
POST AERATION
WEIR
EFFLUENT LINE
PROPOSED CONCEPT
Figure 5. Common wall construction between chlorination and post aeration
17
-------
BASINS & TANKS
Design Concepts
EFFLUENT _--^-
DISC SCREENS
EFFLUENT
INFLUENT
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t
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\
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0 tx
r
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-txJ-]
t
-ixi-
3 IX
I
HXh
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REDWOOD -
-CONCRETE
CONTACT CHAMBER
CONCRETE
140' CONCRETE
INFLUENT
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tllllll'l
HXh
tit tint
ORIGINAL CONCEPT
PROPOSED CONCEPT
Figure 6. Simplify chlorine contact tank valving.
18
-------
BASINS & TANKS
Design Concepts
ORIGINAL CONCEPT
*''
A.-
PROPOSED CONCEPT
Figure 7. Use outboard launders.
19
-------
BASINS & T ANKS
Design Concepts
Delete Headworks Grease Removal
In the original concept, grease removal was provided in a separate basin
located between the grit chamber and the primary clarifier. Also, grease
skimmers were included on the primary clarifiers.
In the proposed concept, the grease removal basin was eliminated, thereby
having the complete grease removal being accomplished at primary
clarification.
Reduce Thickness of Effluent Storage Tank Walls
In the original concept the effluent storage tanks had interior walls 18-
inches thick. The walls were braced at intermediate points by baffle walls
or had no unbalanced pressure acting on them.
In the proposed concept the walls were reduced to 12-inches thick thus
reducing the volume of the concrete required.
Reduce Clarifier Slab Thickness
In the original concept, secondary clarifiers were designed with a 30-inch
slab thickness.
In the proposed concept, the slab thickness was reduced to 20-inch.
Use Precast Circular Tank Walls
The original concept provided two primary clarifiers and three final tanks
which had cast-in-place reinforced concrete walls and effluent launders.
The proposed concept would used precast wall panels either grouted or bolted
together and post tensioned with wire strands on the outside covered with
shotcrete. The launder was cast-in-place.
Use Concrete Channel for Aeration Basin Influent Instead of Pipe
In the original concept the influent to the aeration tanks was distributed
by means of a concrete box with sluice gates and 30-inch pipe for each
unit.
In the proposed concept a concrete channel with stop plates would distribute
the influent to each aeration tank.
Redesign Anaerobic Digester Walls and Mat
The original design proposed a 34-inch thick digester wall which consisted
of 28-inch of reinforced concrete, a 2-inch air space, and a 4-inch brick
layer.
The proposed design was for a 22-inch thick wall consisting of 16-^inch of
reinforced concrete and 6-inch of insulation. The reduction in digester wall
thickness was accomplished using tension rings. A parapet was also
20
-------
BASINS & TANKS
Design Concepts
eliminated from the top of the digester wall, and the digester slab was
redesigned to reduce concrete and reinforcing steel. Overall, an approximate
1/3 savings in concrete and reinforcing steel was accomplished.
Use Single Precast Scum Box ,
The original design used a separate cast in place scum box for each of two'
primary clarifiers. ,
The proposed concept recommended combining the two scum boxes into a single,
precast unit, thereby lowering the construction cost and reducing the number
of control valves required.
Tilt up Baffle Walls in Chlorine Contact Tank - - _
The original concept used conventional 12-inch thick reinforced concrete
walls as baffles in the chlorine contact basin.
The proposed concept reduced installation time by using tilt up baffle
walls. The walls, struts and beams would be cast on the completed floor
slab, set up in place, and welded at the base. Beams and struts. would be
placed and tack welded.
Reduce Effluent Wall Thickness
The original concept utilized concrete channels for collection of the final
clarifier effluent. The walls of the channels were 12-inch thick.
The proposed concept would reduce the thickness of the effluent channels to
8-inch.
Use all Steel Effluent Troughs in Place of Concrete and Steel Troughs ;;-
The original concept proposed to use an outboard concrete trough for a cir-
cular clarifier as well as an inboard steel effluent trough.
The proposed concept would use larger diameter steel effluent troughs and
eliminate the exterior concrete troughs. .
Eliminate Cover on Aerobic Digesters
The original concept included covering the existing primary clarifiers and
aerobic digesters. GaS under the covers was to be collected and cleaned for
odor control purposes.
In the proposed concept the existing primary clarifiers and aerobic digest-
ers would be utilized without covers since odor control was riot a problem in
the existing facility.
21
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BASINS & TANKS
Design Concepts
Omit Preareation BasinUse Preaeration Channels
In the original concept, a preaeration tank was located between the grit
tank and the primary clarifier. The tank utilized mechanical aerators which
were covered to capture and scrub the air for odor control. The primary
clarifiers also had air collection and treatment facilities for odor
control.
In the proposed concept, the preaeration basin were eliminated and replaced-
with an aerated channel. The channel would have a fiberglass cover, but the
air would not be treated for odor control.
Reduce Depth of Slab for Flow Equalization Basin
In the original concept a rectangular flow equalization basin was designed
with a 1.5 ft thick floor.
In the proposed concept, the thickness at the center of the slab was reduced
to 0.5 ft. The perimeter footing retained the 1.5 ft thickness.
22
-------
- PROCESS EQUIPMENT
Flow Equalization
CHAPTER 3 ;
PROCESS EQUIPMENT
FLOW EQUALIZATION " ' .-.--.- -..-.. -.-......
Eliminate Flow Equalization Basin , ; - .. -, ซ
Initially, flow equalization basins were . provided to dampen flow peaks
influent to a plant. . . -
The proposed . concept suggested using variable frequency, type pumps with var-
iable speed drives , to limit the flow peaks, eliminating the need .for flow
equalization basins. ...,,,.
Eliminate Blending Basin . , . , ,,
Flow arrived at the plant through force mains from a series of" remote pump-
ing stations. A blending basin was included in the original design to
homogenize the quality of wastewater from the different force mains. Air
diffusion was used in the blending basin to mix the basin contents.
Elimination of the blending basin was proposed, since sufficient blending
would occur in the grit removal basin and the primary clarifier.
Use Interceptor Storage Capabilities
To equalize wet weather and other peak flows through a plant, an influent
storage basin was proposed. The storage basin would be located on-site,
before the raw wastewater pumping facilities.
An analysis of the 72-inch influent sewer indicated that it contained over
3.5 mgd of usable storage capacity ,at peak flows, which was more than the
proposed capacity of the influent storage basin. It was proposed to use the
storage capacity of the interceptor and eliminate the proposed storage
basins. Coincidentally, because the storage capacity of the interceptor was
greater than the proposed storage basins, the required capacity of the raw
wastewater pumping facilities was also reduced. .
Substitute Swirl Concentrator for Flow Equalization Basin .!.
The original concept provided for flow equalization by use , of a covered
three cell basin, with sludge collection equipment. The basin had a capacity
of 5.5 million .gallons. Coagulants were planned to be added to the equaliza-
tion basin. , . - '.
The proposal was to use a swirl concentrator in lieu of the flow equaliza-
tion basin. Flows in excess of plant hydraulic capacity were to be settled
to remove solids, disinfected, and discharged through a chlorination basin.
23
-------
PROCESS EQUIPMENT
Flow Equalization
Remove Sludge Collection System from the Flow Equalization Basin
In the original concept a covered three cell basin with sludge collection
equipment was provided for flow equalization. Traveling bridge sludge
collection mechanisms were to be provided to collect and remove the sludge.
The proposed concept recommended flow equalization basins without sludge
removal equipment. The sludge would be removed manually.
Eliminate Flow Equalization Basin
Flow equalization basins were provided at the treatment plant to dampen flow
peaks which were caused by several large package lift stations.
The proposed change was to use a throttling valve at the lift station to
limit flow peaks, and thereby eliminate the need for the flow equalization
basins.
Use Concrete Lined Earthen Basin
The original design included concrete ' flow equalization basins with sub-
merged turbine aerators for aeration and mixing.
The use of concrete lined earthen basins of the same volume was proposed.
Because the project was upgrading an existing plant, it was recommended that
the static tubes from existing aerated lagoons to be salvaged and used with
a new blower to insure adequate mixing. The proposed and original designs
are shown in Figure 8.
Pumped Mixing Instead of Jet Aeration Mixing
Originally the flow equalization basin used a -jet aeration mixing system.
The proposed concept recommended using pumped mixing to replace the jet
aeration system.
Eliminate Flow Equalization Basin
In the initial concept flow equalization was provided by a covered three-
cell basin with collection equipment provided to remove the sludge. The
basin was intended to be used during wet weather flow in excess of the
design flow rate. If overflows occurred during a storm, they would discharge
to the plant effluent after receiving chemical aids for coagulation and
disinfection. Raw wastewater remaining after the storm would be treated in
the plant after influent flow dropped below the plant design flow. The basin
was covered and ventilated air from the basin would be treated by chemical
scrubbing.
In the proposed concept, the flow equalization basin would be completly
removed and influent in excess of plant design would be chlorinated and
discharged.
24
-------
PROCESS EQUIPMENT
Flow Equalization
AIR
-------
PROCESS EQUIPMENT
Flow Equalization
Eliminate Flow Equalization Basin Cover
In the original concept a covered three-cell basin with sludge collection
equipment was provided to receive wet weather flows in excess of the design
flow rate.
In the proposed concept the flow equalization basin was designed without
roof or odor control. Odor control for the equalization basin was
unnecessary due to the infrequent usage and the short periods of time it
would be used.
26
-------
PROCESS EQUIPMENT ''-
Pumps - Influent & Effluent
PUMPS - INFLUENT AND EFFLUENT , .
Revise Inlet Direction into Pumping Station
A large effluent pumping station used a rectangular wet well and five pumps.
The wet well was arranged in a manner which required flow to make a 90ฐ
change in direction before reaching the pumps.
A re-arrangement of the wet well was proposed which would equalize the flow
to each of the pumps and eliminate potential dead spots in the wet well.
The re-arrangement was based upon Hydraulic Institue Standards for wet
wells, and eliminated the 90ฐ change'. in direction in the original design.
Figure 9 shows sketches of the original and proposed concepts.
Delete Redundant Wet Well Dewatering Systems
A large interceptor pumping station was designed to handle separate wet
weather flows and dry weather flows. The pumping station was designed as two
separate pumping stations in one structure. Separate wet wells, pumps, and
discharge piping were provided for wet weather and dry weather flows. Pro-
vision was made for separate dewatering systems for the wet weather pump
sump and dry weather pump sump when systems pumps were not in operation or
were down for repairs.
Use of a single sump dewatering system for both the wet weather and dry
weather pumps was proposed, thereby eliminating one of the original dewater-
ing systems.
Variable Speed and Constant Speed
The original design concept used four variable speed pumps in the raw sewage
pump station. The pump station was planned to pump an equalized flow of
12.5 mgd. .
The proposed change modified the system to utilize two constant speed and
two variable speed drive pumps. The constant speed units would be sized to
pump the average flow rate while the variable speed units would be used to
pump the additional flows.
Right Angle Drive Instead of Horizontal Drive
The original concept proposed five gas engine drives for the influent pump
station. The pumps and gas engines were both located below grade in the dry
well, thereby allowing horizontal drive between the engines and pumps.
The proposed concept recommended the installation of the gas engines at
grade, with a right angle gearbox to transmit power to the pumps. The pro-
posal significantly reduced the dry well size. Simplified sketches of the
original and proposed designs are shown in Figure 10.
27
-------
PROCESS EQUIPMENT
Pumps - Influent & Effluent
WET WELL-PLAN VIEW
O Q O
\
7) INFLUENT
PUMPS
ORIGINAL CONCEPT
I
WET WELL-PLAN VIEW
QOOQjD
PUMPS
PROPOSED CONCEPT
Figure 9. Revise inlet to pumping station.
t? V
28
-------
PROCESl EQUIPMENT
Pumps - Influent & Effluent
ws
^
WET WELL
If
_
i
D
3
n
ISCHARGE
I
k 1
^DRYWELL^'V
/^> GAS ENGINE
1
T
h
ORIGINAL CONCEPT
WS
WET WELL
RIGHT ANGLE DRIVE
DISCHARGE
GAS ENGINE
\DRY WELL
PROPOSED CONCEPT
Figure 10. Right angle drive system.
29
-------
PROCESS EQUIPMENT
Pumps - Influent & Effluent
Four Pumps in Place of Five
In the original concept five raw wastewater pumps, each sized at 7,900 gpm
were proposed for the influent pump station.
In the proposed concept four raw wastewater pumps, each sized at 9,900 gpm
would be utilized.
*
Combination of Gas Driven and Electric Driven Pumps
The original concept used five gas engine driven pumps (each 150 HP) in the
influent pump station.
In the proposed concept two gas engine driven pumps and three electric motor
driven pumps, each 150 HP, were used. Two of the three electric driven pumps
would have variable speed controls.
Vertical Pumps in Place of Horizontal Pumps
The original concept proposed using a primary pump station with four hori-
zontal constant speed pumps^to pump 13 mgd average flow to the primary clar-
ifiers. The horizontal pumps were located in a dry well with a superstruc-
ture constructed above the dry well to house the motor control center, air
compressors, stairwell, and equipment hatches and overhead hoist.
The proposed concept would use either three or four vertical pumps in place
of the horizontal pumps, thereby allowing a reduction in the dry well and
building size.
Prefabricated Pump Station for Cast-In-Place Pump Station
In the original concept, the designer proposed a cast-in-place pump station
with four horizontal constant speed pumps. The station capacity was 13 mgd.
The horizontal pumps were located in a dry well, and a building was located
above the dry well to house the motor control center, air compressors,
stairwell, equipment hatches and overhead hoist.
The proposed concept would use a prefabricated pump station with four verti-
cal pumps. The package pump station with adjacent wet well would contain all
the pumps, controls, appurtenances, and elevator access to the below grade
pumping facility.
Vertical Propeller Pumps in Lieu of Screw Pumps
The original concept proposes a secondary effluent pumping station using
72-inch diameter screw pumps each having a capacity of 17,000 gpm and a
lift of 20 feet.
The proposed concept used vertical propeller pumps with a simplified but
deeper wet well.
30
-------
PROCESS EQUIPMENT
Pumps - Influent & Effluent
Switch Sizes of Variable Speed and Constant Speed Pumps
A raw wastewater pumping station was to be constructed with 120 mgd of pump-
ing capacity. Two 40 mgd variable speed pumps were to be used-in conjunction
with two 20 mgd fixed speed pumps.
As a greater percentage of flow occured in the lower. flow ranges, an over-
all increase in pumping station efficiency was proposed by the use of fixed
speed pumps to handle the lower flows and variable speed pumps for the
peaks. Two 40 mgd fixed speed pumps and two 20 mgd variable speed pumps were
. : proposed.
Fixed Speed Pumps for Variable Speed Pumps ,
Four raw sewage influent' pumps we're .called for, each designed as a variable
speed unit. " . | ..-"....-.
Two variable speed and two constant speed pumps were proposed .to eliminate
the need for two 100 HP magnetic drive units.
Combine Separate Effluent and Storm Water Pump Stations into One Station
In the original concept there were two 60 mgd pumping stations, one for the
plant effluent, and one for a storm-water channel located on the .plant site.
Both stations pumped flow to an adj acent river and both had approximately
the same discharge .head.
It was proposed that these two pumping stations should be combined into a
single structure, with use of the same pump (20 mgd) as the standby for both
facilities. Aspects of- the proposal were the use of common wall construc-
tion, a savings in electrical power distribution facilities, and an overall
reduction in .excavation. , , ..
Cooling Water Pumps for Diesels
A large effluent pumping station used two diesel engines to drive two pump-
ing units. Cooling water for the diesels was provided by three (one standby)
electrically-driven cooling water pumps. In the event of a power failure,
the plant - did have standby .generation capability, which would be able to
supply power- to the electric motors driving the cooling water pumps.
The proposed concept recommended driving the cooling water pumps by a gear
drive from the diesel units. One cooling water pump was proposed for each
diesel, eliminating the standby pump in the original design. The three elec-
tric motors in the original design were also eliminated.
Substitute Screw Pumps for Vertical Propeller Pumps ,
Effluent pumping to a nearby river was .planned to be by a 60 mgd pumping
station which would use four 20 mgd vertical propeller pumps.
31
-------
PROCESS EQUIPMENT
Pumps - Influent & Effluent
Screw pumps were proposed as a replacement, using 3 installed at 20 mgd
each, with one 20 mgd standby pump.
32
-------
PROCESS EQUIPMENT
Process
PUMPS - PROCESS
Change Suction and Discharge Valving
An effluent pumping station was designed with manually operated gate valves
on suction and discharge lines, and a 24-inch check valve on the discharge
lines.
A proposal was made to substitute butterfly valves for the gate valves on
the influent and effluent lines. Also, replacement of the check valves on
the effluent lines with motor operated butterfly valves was proposed.
Vertical Turbine Pumps to Eliminate Dry Well
Effluent pumping was originally planned to be by use of centrifugal mixed
flow pumps. Pumps were located in a dry well and drew suction from an
adjacent wet well.
To eliminate the need for the dry well, vertical turbine pumps were proposed
instead of the centrifugal mixed flow pumps. The vertical turbine pumps
would be located directly above the wet well. The proposal eliminated the
dry well and considerable amount of suction valving. Schematics of the
proposed and original concepts are shown in Figure 11.
Add Influent Pumping and Eliminate Effluent Pumping
Influent wastewater flow to the plant was by two conduits, one a force main
and the other a gravity interceptor, the .latter carrying less than half the
- influent flow. Due to the plant layout, and elevation, a portion of the
available head, in the force main was lost at the headworks. The plant layout
required a low lift pumping station for the plant effluent.
The proposed concept recommended some minor plant layout changes which
resulted in raising the headworks elevation and utilization of the head in
the influent force main flow. This change also necessitated the addition of
a screw pump to boost the flow from the gravity interceptor to the new
headworks elevation. The proposed changes, allowed gravity discharge from the
plant, eliminating the need for an effluent pumping station.
Smaller Influent Pumps with a Pump Added in the Future
The original concept called'' for three influent 'pumps of 33.6, 38.5, and
39.5 mgd. The pumps were" to utilize wound rotor motors with liquid rheostat
control.
The proposed concept suggested the ^initial installation of 3 pumps of 24 mgd
each, and the addition of a forth 24 mgd pump 12 years in the future, when
influent flows projection dictated such an addition. The proposed concept
also included use of frequency change for motor speed,control and the use of
squirrel cage motors.
33
-------
PROCESS EQUIPMENT
Process
!>- MOTOR
ORIGINAL CONCEPT
MOTOR
DISCHARGE
ws
PROPOSED CONCEPT
Figure 11. Vertical turbine pumps.
34
-------
PROCESS.EQUIPMENT
Process
Use Self-Priming Pumps
The original design for the sludge pumps used centrifugal pumps located in a
dry pit. The design also included an upper level building above the pit.
The proposed concept recommended using self-priming pumps located at grade
to eliminate the dry pit at the decant .pump station. The recommended system
' eliminated the dry pit,; reduced piping, and eliminated building and venti-
lating requirements. , ,
Use' Return Pumps for Wasting Sludge ,
In the original design/ separate pumps were use for return and waste acti-
vated sludge. , '
The proposed concept recommended using the return pumps for both returning
and wasting activated sludge.
' '
Combine Primary Effluent and Biofilter Recirculation Pump Stations
In the original design, a pump station lifted primary effluent to the wet
well of the biofilter pumping station. The biofilter pumping station pumped
; primary effluent plus biofilter recycle to the top of the biofilter.
The proposed concept recommended combining these two pump stations into a
- single station in order to provide a lower construction cost, fewer pumps
and simpler operation. Sketches of the original and proposed concepts are
shown in Figure 12. ,
Pump Directly to Biofilter'
In the original .design^ the primary effluent pump station lifted primary
; effluent to the recirculation pump station which then pumped primary efflu-
ent and~biofilter recirculation to the top of the biofilter.
The proposed concept recommended reduced the size of the recirculation pump
station and increased efficient energy use when it recommended pumping pri-
mary effluent directly to the biofilter using the primary effluent.pump sta-
tion. The recirculation pump station would then be used only for biofilter
^circulation to maintain the wetting rate on the media. Sketches of the
original and proposed .concepts are shown in Figure 13.
Use Positive Displacement Pumps at Air Flotation Thickeners ;
The original concept used recessed impeller pumps to pump air flotation
thickened sludge from a wet well to subsequent dewatering.
The proposed .concept recommended positive displacement pumps. It was noted
that experience with the original pumps indicated that recessed impeller
pumps would air lock when used in this application.
35
-------
PROCESS EQUIPMENT
Process
BIOFILTER
BIOFILTERS
RECIRCULATION
ORIGINAL CONCEPT
BIOFILTERS
RECIRCULATION
PROPOSED CONCEPT
Figure 12. Combine pumping stations.
^BIOFILTER
"EFFLUENT
.BIOFtLT.ER
EFFLUENT
36
-------
PROCESS EQUIPMENT
Process
BIOFILTER
PRIMARY
EFFLUENT
P.So
BIOFILTERS
RECIRCULATION
i
ORIGINAL CONCEPT
PRIMARY
EFFLUENT
P.S.
RECIRCULATION
PoSo ~
BIOFILTERS
PROPOSED CONCEPT
^_ BIOFILTER
EFFLUENT
BIOFILTER
EFFLUENT
Figure 13. Pump primary effluent directly to bio-filters.
37
-------
PROCESS EQUIPMENT
Process
Substitute Centrifugal Returned Activated Sludge Pumps for Screw Pumps
In the original concept, screw pumps were specified for return activated-
sludge pumping to a channel and hence to the aeration basin. Pump control
was to be by either speed control or wet well level control.
In the proposed concept, centrifugal pumps were provided for return acti-
vated sludge pumping. Speed control or discharge valve throtting was
proposed for rate control. Figure 14 shows before and after sketches.
Vertical Mixed Flow Pumps for Return Activated Sludge
The original concept used horizontal single stage centrifugal pumps for
return activated sludge. Four pumps were to be used with one to be added in
the future. A wet well/dry well pumping station was planned.
In the proposed concept, pump* selection was changed to vertical mixed flow
(wet pit) pumps and the building size was reduced. The dry well was elimi-
nated in this concept. Figure 15 shows sketches of the original idea and
proposed idea. , . ;
Use Variable Speed Vertical Mixed Flow Pumps for Filter Influent
The original concept called for four screw pumps to.lift final effluent to
the tertiary filters. The pumps were located at the tertiary filter building
and the screws are exposed to the weather while drives and pump discharges
were enclosed in a building.
The proposed concept used four vertical pumps driven by variable frequency
drives. The pumps and drives were enclosed in a smaller building while a
portion of the wet well was exposed to the weather. Figure 16 shows sketches
of the original and proposed concepts.
Vertical Turbine Pumps in Place of End Suction Backwash Pumps
The original concept uses ,3 - 7200 GPM end suction backwash pumps.
The proposed concept recommended using 2 - 10,000 GPM vertical turbine back-
wash pumps with separate backwash supply and backwash waste headers
provided.
Use Vertical Pumps Instead of Horizontal Pumps
The original concept used horizontal centrifugal pumps for return of nitri-
fied secondary effluent and" nitrified return sludge. Pumping head was 21"
TDK.
Use of vertical mixed flow pumps in the return
recommended to eliminate the dry well.
sludge wet well was
38
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PROCESS EQUIPMENT
Process
CHANNEL TO
AERATION BASIN
WETWELL S
WATER SURFACE
PIPE FROM
CLARIFIER
ORIGINAL CONCEPT
HAS PUMPING
STATION
9
.oJ
I
PROPELL
.OR PUMP
: <
COVERED
AERATION BASIN
PROPOSED CONCEPT
Figure 14. Use mixed flow pumps in lieu of screw pumps.
39
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PROCESS EQUIPMENT
Process
RETURN ACTIVATED
SLUDGE HEAD TANK
RETURN ACTIVATED
SLUDGE CHANNEL
MIXED LIQUOR
CHANNEL
RETURN SLUDGE
PUMP
ORIGINAL CONCEPT
RETURN ACTIVATED
SLUDGE HEAD TANK
RETURN ACTIVATED
SLUDGE CHANNEL
31U3"
RETURN SLUDGE PUMP
MIXED LIQUOR
CHANNEL
STAIRS IN THIS AREA
PROPOSED CONCEPT
Figure 15. Use vertical mixed flow pumps.
40
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PROCESS EQUIPMENT
Process ,
FILTER
SCREW PUMP ROOM
ORIGINAL CONCEPT
PROPOSED CONCEPT
> FILTER
INFLUENT
CHANNEL
B
Figure 16. Use vertical mixed flow pumps instead of screw pumps.
41
fc-
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PROCESS EQUIPMENT
Process
Eliminate Digester Sludge Transfer Pumps
In the original design, two pumps were provided to transfer sludge from one
digester to another.
The proposed concept suggested eliminating the sludge transfer pumps and
using the recirculation pumps for the transfer operations. The proposal
eliminated building area and simplified piping. Although the transfer of
sludge would take about four times longer using the recirculation pumps,
this was not considered to be critical since transfer of sludge is an
infrequent operation.
Use Aluminum Zip-Rib Instead of Aluminum Checkplate for Covers on Pump Station
and Pretreatment Complex *>
The initial design used 3/8" thick aluminum checkplates to provide walking
> surfaces above all channels and basins in the raw sewage pumping and pre-
treatment areas.
The proposed concept recommended a lightweight cover system of aluminum
zip-rib. In the area of the comminutors and flumes, the aluminum checker-
plate covers were retained to allow unrestricted access for plant personnel
and the public as a viewing platform during tours.
42
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PROCESS EQUIPMENT
Flow Measurement
FLOW MEASUREMENT
Eliminate .Flow Meter
Flow to a chlorine contact chamber was originally through an 84-inch pipe,
which was split into 2-54" pipes for diversion to two separate chlorine con-
tact chambers". A. metering pit was to be provided with valves and flow
meters to divide the flow between the two contact chambers./
Deletion of the flow meters and associated valving was recommended, with
control of the flow split to be accomplished hydraulically.
43
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PROCESS EQUIPMENT
Screening
SCREENING
Use Existing Mechanical Screens
An existing facility was to be abandoned and a new 1.5 mgd plant was to be
constructed a short distance away. All existing facilities were planned to
be abandoned, and a pumping station was to be constructed to pump flow to
the new plant. At the new plant, mechanically cleaned bar screens, with a
standby manually-cleaned bar screen in a bypass channel, were included in
the design.
Continued use of the existing manually cleaned bar screens at the existing
plant prior to pumping to the new plant was recommended.
Eliminate Screw Conveyor
The original headworks design provided for screenings to be discharged from
three bar screens onto a belt conveyor. The belt conveyor discharged into
the hopper of an inclined screw conveyor. The screw conveyor dewatered the
screenings and discharged to a screenings bin for transportation by forklift
to the energy/solids building.
It was recommended to eliminate the screw conveyor and extend the belt con-
veyor to discharge directly into the bin. The bottom of the bin would be
perforated to permit the screenings to dewater to the floor drain below.
Haul Screenings to Sanitary Landfill '
The original idea was to incinerate screenings on site at the plant.
The proposed concept recommended reducing the energy requirements by elimi-
nating the incinerator and hauling the screenings directly to a landfill
where odor would not be a problem.
Use Mechanical Screen Instead of Barminutor
The original design included a barminutor in the head works.
The proposed concept recommended using a mechanical screen.
Eliminate Standby Mechanically Cleaned Bar Screen
The headworks was designed with two mechanically cleaned bar screens each
having capacity for the entire plant flow. One of the screens was for nor-
mal operation and one was for standby.
The proposed concept recommended that the standby screen be converted to a
manually cleaned screen.
44
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PROCESS EQUIPMENT
Grit Removal
GRIT REMOVAL
Grit Removal Channels in Lieu of Pista Grit Chambers
As originally designed, two pista grit chambers were provided for grit
removal. An airlift was used to lift grit from each chamber into a slurry
pipe for conveyance to a container.
The proposed concept recommended using four grit channels approximately
eight feet wide by 50; feet in length. The grit would be handled using con-
ventional collectors, conventional grit elevator, and conveyed using a
screw-type conveyer. Sketches of the original and proposed, concepts are
shown in Figure 17. '..'..'
Delete Grit Washer and Pump Directly to Sludge Storage Basin
As initially designed, the grit handling system included pumping grit from
an aerated grit chamber to a grit washer and a_ grit cyclone. The grit was
then to be hauled to a landfill for disposal. ''
To simplify the operation, it was recommended that the grit be pumped
directly to sludge storage basins, which store digested, dewatered sludge
prior to trucking to landfiJLl. The proposal eliminated the need for separate
grit treatment and hauling. ,
Eliminate Grit Washer and Use Cyclone
The original design included a grit system consisting, of an aerated grit
chamber, a grit washer and a grit cyclone.
The proposed concept recommended eliminating the washer and only using the
aerated grit chamber and the cyclone"to concentrate the grit.
Replace Tube Conveyor and Storage with Belt Conveyor and Dumpster
The original design of the headworks included the use of tube conveyors to
transport screenings and grit to a storage tank. .
The proposed concept recommended elimination of the silo storage tank arid
the tube conveyor and using a belt conveyor and a dumpster box.
Eliminate Truck Scale to Measure Grit Removal From Plant Site ,
Trucks were planned to remove dewatered grit from the plant site, and a
truck scale was planned for truck weighing.
Elimination of the scale was proposed with grit measurement to be accom-
plished by measuring grit volume using marks on the side of the trucks.
According to sand and gravel haulers, this technique should give about 1%
accuracy. The uniform density of grit would be beneficial in attaining
accurate results. At the plant under consideration, scales were also
45
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PROCESS EQUIPMENT
Grit Removal
LU
Z
D-
LU
U
Z
o
u
o
< /
5 /
a:
\
0.
LU
u
o
u
LU
tO
O
Q.
O
t-~
l-l
0)
Cn
H
46
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PROCESS EQUIPMENT
Grit Removal
'available in the digester' area*/' -and these were planned to -be used on.' a
periodic basis to check the accuracy of the proposed technique.
Simplify Grit Removal from Primary Sludge ..-'.-'
Cyclone degritters were planned for degritting primary sludge. The plant was
designed with four primary clarifiers, four sludge pumps and four cyclone
degritters. The primary sludge pumps were to be located 600 feet from the
cyclone degrittjers. ' , . . ;
Use of one primary sludge pump and cyclone degritter for two primary clari-
- fiers was proposed with a standby pump and degritter. Sketches of the
original and proposed concepts are shown in Figure 1.8. ,;,
Use Aerated Grit Chamber in Place of Gravity Grit Chamber
The original concept proposed using a shallow gravity grit chamber in
parallel with an existing unit of the same type. The new' grit chamber would
be built on a severely sloping grade, thus requiring foundation piles or
. other special support; , .-. -
, The proposed concept recommended using an aerated grit chamber to handle the
entire-design flow. Because of the greater depth involved with the aerated
grit chamber, special foundations and retaining walls were not required. The
existing gravity tank would be retained for periods when the aerated tank
was out of service. , .-.'... ;
Substitute Low Head Grit Basins for Velocity Controlled .. ...
The ;original plan . used two velocity controlled grit basins and a;
barminutor. . t. .. . -
The proposed change recommended using two ''more reliable;'lbw' head grit basins
and a mechanically cleaned screen. The proposed system would provide contin-
uous grit removal and would not be dependent on/an operator.
47
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PROCESS EQUIPMENT
Grit Removal
8 * 8 ^8 f8
TO PRIMARY CLARIFIERS
ORIGINAL CONCEPT
8
O O O O
TO PRIMARY CLARIFIERS
PROPOSED CONCEPT
Figure 18. Simplify grit removal.
PUMPS ON
TIME CLOCK (TYP)
CYCLONE
DEGRITTER (TYP)
CONTROL VALVE
ON TIME CLOCK
(TYP)
48
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PROCESS EQUIPMENT
Clarifiers . ".
CLARIFIERS ' ..--a* :M^. ,..., ....... . .. , .,,...;... , ...
Replace Primary Effluent Channel with Pipe
Effluent from the primary clarifiers originally was collected in a common
channel and piped over an interstage pumping station.
The proposed concept recommended replacing the effluent channel with a pipe
and transferring the effluent directly to the interstage pumping station. A
sketch of the before and after concepts is shown in Figure 19.
Eliminate Low Air Pressure Scum Control System
In the original design concept, rectangular primary sedimentation basins
were equipped with a low pressure directional air system to move the scum to
the head end of the basin. The basin also had an air scrubber system for.
odor control. .;.-- ' ' ' "
The proposed concept recommended' eliminating the low pressure directional
air system for. scum removal and replacing it with .more positive, less energy
intensive, collection mechanisms using flights or separate drive system. The
recommended system reduced the required odor scrubbing capacity needed for
the system. Figure 20 shows sketches of the original and proposed concept.
Eliminate Settling Tubes in Secondary Clarifiers
The initial design of "-.rectangular- secondary clarifiers included tube
settlers in the last 115* of :each clarifier basin. ", .
The proposed recommended eliminating the tube settlers to reduce construc-
: tion and O&M costs. Although some loss of suspended Solids removal
efficiency would occur, the change was considered negligible.
49
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PROCESS EQUIPMENT
Clarifiers
Primary """**
Clarifiers
Effluent channel
(Future)
ORIGINAL CONCEPT
To interstage P.S.
Primary
Clarifiers
(Future)
36" Collection pipe
To interstage P.S.
PROPOSED CONCEPT
O
O
O
Aeration Basin
distribution flume
Interstage P.S.
L
Aeration
Ba s i ns ,
O
-O
O
"Aeration Basin
Distribution flume
Interstage pumps
L
Aeration
Basins -
Figure 19. Replace primary effluent channel with pipe.
50
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.PROCESS EQUIPMENT
Clarlflers , .
Helical skimmer
i
4-3" Air headers
ORIGINAL CONCEPT
Scum trough
PROPOSED CONCEPT
Air' from blower
Chain & flight
collectors ."-".
Chain & flight
col lector ' .
Figure 20.
Replace low pressure air scum control system with
collection mechanism. . ;
51
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PROCESS EQUIPMENT
Trickling Filters
TRICKLING FILTERS
Modify Existing Distributor Instead of Replacing
An existing plant used a trickling filter to treat primary effluent. To
maintain sufficient flow through the distributor and the trickling filter,
the system was capable of up to 50% recycle. Planned upgrading of the plant
by adding activated sludge treatment after the trickling filter eliminated
the capability of recycling flow through the filter, and without recycle,
the primary effluent flow was incapable of turning the distributor arm.
Plans for upgrading the plant included a new distributor arm.
The proposed concept recommended blocking off two opposing distributor arms
with blind flanges, thereby increasing the flow through the remaining two
arms by 50%. The assumption was made that the distributor should turn sat-
isfactorily with 2 arms blocked off, but an alternate solution was to remove
two opposing arms.
52
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PROCESS EQUIPMENT
Aeration Systems
AERATION SYSTEM
Change Air Piping Material
In the original design concept, a steel cylinder concrete pipe was utilized
from the blower building to the aeration basins, with ductile iron pipe used
for distribution at the aeration tanks.
A piping material change from the steel cylinder concrete pipe and ductile
iron pipe to steel pipe with multiple wrap coating was proposed.
Increased Aeration Basin Depth Change Type of Diffusers
An aeration basin depth of 15 feet and fine bubble dome diffusers were
used.
An increase in the aeration basin depth from 15' to 20' was proposed, and
change to coarse bubble static diffusers to increase oxygen transfer
efficiency, and reduce power costs.
Emergency Drive of Air Compressors for Pure Oxygen Plant
Pure oxygen was to be generated on-site for use in secondary treatment.
Three 20 ton/day units were planned, two for normal operation and one for
back-up unit. Each of the air compressors was driven by an electrical motor
under normal operation, and during a power outage, any two of the three
could be driven by gas engines. Digester gas would be used as the gas source
for these engines.
The proposal concept recommended using two air compressors, each rated at
100% of required capacity. A single gas engine, which could drive either of
the compressors, was proposed for use during power outages. A sketch of the
original and proposed concepts is shown in Figure 21.
Use Smaller Blower for Low Pressure Air Supply
In the original , concept, low pressure air for aerating the aeration tank
influent and effluent channels was taken off the high pressure line to the
aeration tank.
The proposed concept recommended two low pressure blowers (one or standby)
with an equivalent reduction in the main blower size.
Use Welded Steel Pipe in Place of Flanged Ductile Iron Pipe
In the original design, pipe from the air blower building was specified to
be flanged ductile iron piping.
The proposed concept recommended using welded steel or stainless steel
blower piping. -
53
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PROCESS EQUIPMENT
Aeration Systems
GAS
ENGINE -
\i
3 AIR COMPRESSORS-
D
D
AIR COMP. ROOM
D
iAS ENGINE
FIRST FLOOR PLAN
ORIGINAL CONCEPT
GAS ENGINE
D
Jzd
-AIR COMPRESSORS
FIRST FLOOR PLAN
PROPOSED CONCEPT
Figure 21. Emergency drive for pure oxygen air compressor system.
54
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PROCESS EQUIPMENT
Aeration Systems
Use Plastic Insert type Vehturi Meters' for Airline .Metering '" ! ' ' *.;"=*-:-'?;-?ซ-.'<.
The original concept proposed using venturies on the aeration lines.
In the proposed concept plastic insert type venturies with a 20 year life '
are used for airline metering.
Reduce Number of Blowers, Use Dual Drive, and Increase Speed "
The original concept for the aeration system was to use six blowers operat-
ing at 1200 RPM. Three blowers were to be motor driven, two dual fuel (meth-
, ane .and natural , gas) engine driven, and one engine driven using only meth-'
ane. To provide the required air delivery, only 4 of the 6 blowers were
required.
a . ^j-- r _,;-.. - - -
The proposal was to use four 1750 RPM blowers which were dual drive, motor
or engine driven. When digester gas ' was available, -the blower would be
driven by the engines, and during other times by the motors. Three of the"
units were for normal operation, and one was standby* : A sketch showing the
before and after concepts is shown in Figure 22.
Move Blower Building Closer to Aeration Basin ' ' '..
A blower building was to be constructed to provide air to a new nitrifica-:
tion basin.
The proposed concept recommended moving the blower building to allow a
'. common wall with the new nitrification basins.
Mechanical Aeration to Replace Diffused Aeration in 1st and 2nd Stage Aeration
The original concept utilized a diffused air system for first and second
(nitrification) biological treatment. The first stage was completely mixedr
and the second stage was plug-flow.
The proposed concept recommended using mechanical surface aerators instead
of the swing diffuser aerators. Aerators were 'proposed to be dual speed in
\ the 1st stage aeration with one aerator per aeration basin. To vary aeration
capacity in the 2nd stage, two dual speed aerators were recommended in each
2nd stage aeration basin. '-:.-
Lift Out Drop Pipes Instead of Swing Drop Pipes
Aeration basins were designed "with "tee" walls between the basins, and the
walkway between basins was at the top of the "tee". The main air header was
attached to the underside of the tee, and was used to supply air to basins
on each side of the tee wall. Between the diffusers and the main air header.
were swivel joint (top) and knee jointed (mid-point) drop pipes.
The proposal was to replace the swivel joint drop pipes with lift out drop
pipes. To check diffusers, the lift out pipes would be disconnected at a
55
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PROCESS EQUIPMENT
Aeration Systems
3 MOTORS 300 HP
6 BLOWERS
EACH AT 8000 CFM
3 ENGINES 350 HP
4 MOTORS 300 HP
4 BLOWERS
EACH AT 10.000 CFM
4 ENGINES 400 HP
r. .1
ORIGINAL CONCEPT
J I
PROPOSED CONCEPT
Figure 22. Use dual drives for blowers.
56
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PROCESS EQUIPMENT
Aeration Systems
quick disconnect joint, and then lifted out. A sketch of the original and
proposed concepts is shown in Figure 23. -
Constant Speed/ Centrifugal Blowers Instead of Variable Speed, Positive Dis-
placement Blowers
The original design proposed rotary positive displacement blowers with vari-
able speed drive motors to control the volume of air and power consumption
for the aeration system.
The proposed alternate was to install centrifugal type blowers with constant
speed drives and use valves to throttle the blower to vary the air volume
and power consumption. ','-..
Use Fixed Headers for Air Supply Piping :.
The original aeration concept was a high efficiency fine bubble diffusion
system, using drop pipes from a main aeration header near the top of the
basins.
The proposed concept recommended installing the main air header at the
bottom of the tank, and attaching the tube headers directly to the main air
header. This concept eliminates the need for drop pipes and fitting, but it
would require the basin to be dewatered for diffuser maintenance.
Fine Bubble Diffusion in Lieu of Coarse Bubble Diffusion
The original concept proposed coarse bubble diffusion as the oxygen transfer
system for both secondary and nitrification aeration.
The proposed conqept recommended switching,.to fine bubble diffusion because
of the higher transfer efficiency and lower energy costs.
Replace Air Flow Tubes with Orifices
The original concept used flow tubes for measurement of air flow to the
aeration basins.
The proposed concept would use flange mounted orifice plates to measure air
; flow. . _' ...'_- ' ..-'....-.
Mechanical Surface Aerators in Place of Diffused Air System
The original concept used conventional diffused air system utilizing
blowers, a blower building, air distribution piping, and baffle walls in
aeration basins.
The proposed concept would utilize mechanical surface aerators which provide
a more efficient oxygen transfer and eliminate the need for a blower
building, blowers, and baffle walls.
57
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PROCESS EQUIPMENT
Aeration Systems
D1FFUSER
ORIGINAL CONCEPT
HANDRAIL
LIFT OUT DROP PIPE
Figure 23. Replace swing drop pipes with lift out drop pipes.
58
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PROCESS EQUIPMENT
Aeration Systems
Use Single-Louver Control System
In the original concept, louvers on aeration tank blower inlets were indi-
vidually controlled. A louver would be opened and closed with the corres-
ponding blower, with the amount of .opening regulated by the air pressure in
the inlet air channel. As designed, the system could search for the correct
louver opening, with louvers fighting each other unless complicated control
systems were used.
In the proposed concept, only one control system would be used to regulate
the opening of all the louvers online. This number of louvers open would
vary from one to five louvers depending upon the number of blowers operat-
ing, 'whether screens were clogged by leaves or snow, or other conditions.
The proposal eliminates four sets of controls and associated hardware,
software, and engineering. ...:--
Use Common Air Piping for Aeration
The original concept proposed one air header pipe for each aeration basin.
The proposed concept recommended using one air header for each two tanks.A
header pipe' for a single basin was only required when there was an odd
number of aeration basins.
Provide Single-stage Oxygen Plant
I ' ' : " ''. ' '
The original concept used a two-stage activated sludge system with carbon-
aceous BOD removal in the first stage "and nitrification in the second stage.
The plant utilized a pure oxygen process for each stage.
In the proposed .concept a single-stage pure oxygen activated sludge was
used, thereby eliminating the intermediate clarification step and providing
a more compact plant.
Substitute Pressure Swing Adsorption for Cryogenic Oxygen System
In the original concept pure oxygen aeration was used for the two stage
activated sludge system. The oxygen,was provided through cryogenic genera-
tion which has a limited turndown .capacity. . .
In the proposed concept pressure swing absorption oxygen generation was used
thus providing substantial turndown capability to meet various oxygen
requirements.
Substitute Anaerobic Filter for Periodic Peak Load Treatment
In the original concept the treatment plant was designed to treat the aver-
age flow with a two-stage aerobic biological process. This treatment scheme
included treating a seasonal wasteload from a food processing plant.
59
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PROCESS EQUIPMENT
Aeration Systems
In the proposed concept the food processing plant waste was pumped to the
treatment plant in a separate pipeline. The proposed treatment for the food
processing plant waste would be an anaerobic filter, which would recover
energy as methane gas and reduce the BOD load to the plant. The design peak
BOD to the main plant would be reduced 37.7% and average loadings 19.5%
using this concept. The existing trickling filters would be renovated for
the anaerobic filters by adding covers, improving underdrain structure and
providing radial collector pipes from the existing turntable structure.
Change Aeration Basins to Complete Mix Activated Sludge
The original design included an aeration system consisting of long narrow
basins designed to permit plug flow, step feed, or contact stabilization
activated sludge. The return activated sludge piping and inlet piping were
set-up to permit any and all of the above variations.
It was recommended that the basins be converted to complete mix basins in a
single activated sludge operating scheme. The basins for complete mix elimi-
nated much of the piping and intermediate walls associated with the original
design. The proposed and original concepts are shown schematically in Figure
24.
Eliminate Spray System in Aeration Tanks
The original design concept included froth control using spray headers and
nozzles around the aeration basins.
The proposed concept recognized that froth was not a problem in the existing
plant and that it would not be a problem in the new plant, except during
plant startup. It was recommended to eliminate the froth control system in
order to lower construction cost.
Submerged Turbines Instead of Diffused Air
In the original design, aeration was to be provided using centrifugal
blowers.
It was recommended that submerged turbines be installed in the basins and
new smaller centrifugal blowers, with a lower operating cost, be used.
Remove Covering from Biofilters
The initial design concept included two biofilters covered with geodesic
domes.
It was proposed to use the same filters and remove the covers.
Replace Mixed Liquor Channel with Pipe
Originally, the mixed liquor from the aeration basin discharged to a channel
which passed between the secondary clarifiers and was.used to distribute the
flow.
60
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PROCESS EQUIPMENT
Aeration Systems
FROM PRIMARY CLARIFIERS
' I FLOW CONTROL GATES TYP) f~*" SECTION
PLUG FLOW REACTOR
STEP FEED CHANNEL
PRIMARY EFFLUENT
DISTRIBUTION CHANNEL
1
MIXED LIQUOR
COLLECTION CHANNEL
TO SECONDARY
CLARIFIERS
AIR
AIR
FROM PRIMARY
ปซ-
CLARIFIER
FLOW
DISTRIBUTION
BOX
ORIGINAL CONCEPT .
T T T T
7~~
-T-*- - .
-rz^:. ,
. * '
T T T T
. *.
FIXED DIFFUSERS
SECTION
SECTION
REACTOR
i
OVERFLOW PIPE
OR WEIR ( TYP)
^
PRIMARY EFFLUENT
DIFFUSER PIPE
TO SECONDARY
CLARIFIER (TYP)
SURFACE AERATORS
OVERFLOW
PIPE (TYP)'
=*
SECTION
PRIMARY EFFLUENT
DIFFUSER PIPES
PROPOSED CONCEPT
Figure 24. Use complete mix activated sludge.
61
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PROCESS EQUIPMENT
Aeration Systems
The proposed system was to replace the MLSS channel with pipe and distribu-
tion boxes at each pair of secondary clarifiers. This system required the
construction of multiple distribution boxes and had reduced access to the
pipeline. However, the recommended system was less costly and provided
better scum control since no scum formation would occur until the effluent
reached the distribution box. At the distribution box the scum would settle
much better than in a reinforced concrete channel as originally planned.
Figure 25 shows sketches of the original and proposed ideas.
Use One 70 ton Cold Box in Place of 2-35 Ton Boxes
The initial design consisted of a cryogenic oxygen production plant consist-
ing of two 35 ton cold boxes, two 100% compressors, and two 70% compressors
used as support facilities.
It is recommended that a single 70 ton cold box with required support facil-
ities be used in place of the two 35 ton boxes. The required support facili-
ties then included a single 100% compressor and a single 70% compressor.
Use Oxidation Ditch Instead of Extended Aeration
The original design concept included extended aeration with submerged tur-
bine aerators. The original concept also provided aerobic digestion of
sludge.
To provide simplier operation and more reliable treatment, the proposed con-
cept suggested using an oxidation ditch with brush aeration. This system
required no primary treatment and no aerobic digestion.
Use Activated Bio-Filter (ABF) Process Instead of Extended Aeration
The original design was an extended aeration system with submerged turbine
aerators.
The proposed concept recommended using the ABF process with the biofilter
followed by short aeration basin using mechanical aerators. The proposed
system could tolerate shock loads better, was more energy efficient, and
eliminated equalization storage.
Centralize Air Supply System
The original design concept included blowers located at three different
locations with a total blower capacity of 2,000 CFM.
The proposed concept suggested centralizing the air supply system at a sec-
ondary control building. The proposed design increased the blower capacity
to 2,500 CFM, but eliminated two blowers, and reduced housing requirements.
62
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PROCESS EQUIPMENT
Aeration Systems
oo-
Aeration Basins
Final
Clarifiers (typ)
ORIGINAL CONCEPT
Aeration Basins
60" pipe-j
PROPOSED CONCEPT
Distribution weirs
Final
Clarifiers (typ)
F i na I
Clarifiers (typ)
Distribution
boxes
Final
'. Clarifiers (typ)
Figure 25. Replace mixed liquor channel with pipe.
63
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PROCESS EQUIPMENT
Aeration Systems
Use Aluminum Covers Rather Than Concrete Over Aeration Basins
The original design of the aeration basins in a pure oxygen plant included
concrete slab covers.
The proposal recommended using aluminum covers in place of concrete slabs.
64
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PROCESS EQUIPMENT
Disinfection
DISINFECTION. " '.'. ;._'.'"......'.' . .'....
Use Ozone Instead of Chlorine
The plant utilized high rate trickling filters for carbonaceous BOD removal,
and .pure oxygen activated sludge for nitrification . On-site oxygen genera-
tion facilities were planned. Chlorine with dechlorination was required for
effluent disinfection.
The proposed concept recommended -. using ozoriation instead of chlorination ,
since pure oxygen generation facilities were already planned for the site.
Reduce Chlorine Contact Basin Size
Plant effluent was disposed to a deep-well system near the plant site. A
chlorine contact basin was used to meet disinfection requirements prior to
flow diversion to the deep-well system.
Use of the deep-well system capacity to provide a portion of the overall
chlorine contact time, similar to an outfall, was proposed. This proposal
resulted in a 40% reduction in the size of the chlorine contact chamber.
Use Tank Trailer for SO2 and
Storage
The original concept used large cylinders for SO2 and C19 storage in a
building.
The proposed concept recommended using tank trailers with a capacity of 18
tons each to deliver and store SO2 and C12ซ The required building size
would be reduced by 2300 square feet.
Revise Location of Chemical Injection Points
The original concept was for chlorine contact tanks which provided approxi-
mately 15 minutes detention time from the tank inlet at maximum flow.
The proposed concept was to move the point of chlorine application from the
inlet of the chlorine contact tank upstream and also to move the point of
the sulfur dioxide application from the outlet of the chlorine tank down-
stream. The lengths of influent conduit and effluent conduit would provide
additional contact time for the chlorine,. .The additional volume in these
conduits permitted shortening of the contact tanks, and reducing the number
of concrete piles, excavation and backfill.
Reduce the Number of Chlorine Cylinders
The original design concept included room for two operational cylinders,
plus a storage capacity for fifteen chlorine cylinders. A bridge crane was
provided to move the cylinders . The chlorine system was designed to provide
disinfection for the entire plant flow.
65
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PROCESS EQUIPMENT
Disinfection
The proposed concept recognized that it was not necessary to provide disin-
fection for the entire plant flow and that only the portion of flow used for
reclamation needed be chlorinated. The proposal recommended cutting the
storage area in half to provide room for five cylinders plus an area for the
two operational cylinders. Also, it was recommended that the bridge crane be
replaced with a monorail crane.
Reduce Chlorine Contact Chamber Size
In the original design, the chlorine contact tank and three chlorinators
were sized for disinfecting the entire plant flow. A portion of the flow was
to be used as reclaimed water.
In the proposed recommendation, the chlorinators would continue to be sized
for all of the plant flow, but the size of the chlorine contact tanks would
be reduced so that only a portion of the effluent would enter. The reclaimed
water would attain an adequate contact time while in plug flow through the
pipeline to its reclamation use.
Eliminate Chlorine Contact Tank Bypass
The treatment facilities were to be constructed in two phases. In the orig-
inal phase, a chlorine contact basin bypass line was to be constructed in
order to facilitate the additional chlorine contact basins construction.
The chlorine contact basin drains connected to the bypass line.
It was recommended to eliminate the bypass under the chlorine contact tank.
The proposed change would result in some loss of flexibility during con-
struction. However, the effluent flumes would permit operation of the con-
tact basins while the new basins are being constructed. The entire flow
would be diverted to one-half of the chlorine contact facilities for short
periods when the new basins were being connected into the flumes.
Ton Containers Instead of 150 Ib Containers for Cl^ and SO? Containers
The original design called for chlorine and sulfur dioxide to be dispensed
from 150 Ib cylinders with tank-mount type gas feeders.
The proposed concept recommended dispensing chlorine and sulfur dioxide from
1-ton cylinders with the same type of feeders. The proposed system would
provide less frequent changeovers and more reliability due to increased
storage capability.
Replace SOp Mechanical Mixer with a Hydraulic Mixer
The initial design mixed SOg with plant effluent by mechanical jet mixer.
The proposed concept suggeted mixing the SC>2 by hydraulic mixing at the
chlorine contact basin effluent weir.
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PROCESS EQUIPMENT
Disinfection
Simplify Chlorine Scrubbing System
The initial design included a chlorine scrubbing system to collect and scrub
chlorine gas in the event of a chlorine cylinder break.
Realizing the high expense of this system, the VE team recommended elimina-
ting spent caustic storage, redundancy in pumps and fans, and all but the
most basic controls. The proposed system layout consisted of a scrubber,
pump, a 3500 gallon sump tank, and a chlorine detection system to automat-
ically start the system. The sump tank would be filled with caustic solution
from 55 gallon drums and diluted with water to a 10% concentration. When
the scrubber system was activated, the contents of the system would be
pumped through the scrubber and then back into the sump. Solution would con-
- tinuously recirculate until the emergency passed and the scrubber shuts
down. The sump could then be drained and refilled as needed after emergen-
cies to supply fresh caustic. ,
Reduce Dechlorination Tank Size
The original concept used open channel mixing of sulfur dioxide, in the
dechlorination step, followed by 5 minutes detention in a baffled channel.
In the proposed concept, a flash mixer for instantaneous contact was used,
followed by a contact basin with about one-half the original contact time.
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PROCESS EQUIPMENT
Filtration
FILTRATION
Package Steel Filters Replacing Reinforced Concrete Structures
Filters for tertiary filtration were to be constructed using reinforced
concrete tanks. "
Package steel tanks were proposed as a substitute for the reinforced con-
crete structures, with the filters constructed and shipped for immediate
installation. Concrete channels were to be used for influent distribution,
while filter effluent and overflow connections to the filter were by means
of header pipes.
Use Surface Washers in Place of Air Scour
The original concept proposes to use blowers to -provide air scour for
supplemental agitation during filter backwash. Blower's were provided in each
filter gallery.
The proposed concept would use a surface wash system which would consist of
turbine pumps with two surface arm washers per filter located just above the
media. The nozzles on the wash arms will both rotate the arms and agitate
the media.
Use One Backwash Rate Controller in Place of Two
The original concept used one backwash pump in each of two pipe galleries,
and an interconnection pipe between galleries. The pump arrangement required
two 24-inch backwash rate of flow controllers.
The proposed concept recommended locating both backwash pumps in one filter
gallery and eliminate one backwash rate flow controller. Motor controls
would be all located in the same area.
Eliminate Effluent Rate Controllers on Declining Rate Filters
The original concept proposed declining rate filters for filtration. It also
included rate of flow controllers on the effluent from the filters.
The proposed concept recommended eliminating the rate of flow controllers
because the declining rate filter concept assumes a declining rate flow
through each filter as the head loss increases and a splitting of flow
between the filters based on the varying head losses. In order to control
the maximum rate of flow through the filter it was proposed to calibrate the
rate of the flow through the effluent butterfly valve by using orifice
plates or a propeller meter.
Replace Hydraulic Valve Operation System with Pneumatic System
The original concept proposed to use a hydraulic valve operation system for
filter process valves.
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PROCESS EQUIPMENT
Filtration
The proposed concept would replace the hydraulic system with pneumatic
valves for all process'valves, and delete the fluid return pipe system.
Reduce Gullet Width by One Foot ,
The original concept proposed using 5 foot wide gullets in the filters.
The proposed concept would reduce'the. overall structure length by reducing
the gullet width to 4 foot (without affecting the backwash operation).
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PROCESS EQUIPMENT
Post Aeration
POST AERATION
Use Turbine Aerators
An existing chlorine contact chamber was to be converted to a post-aeration
basin/ with diffused aeration being used to supply the air and turbulence
required for reaeration.
Submerged turbine aerators were proposed to provide the required air and
turbulence.
Cascade Aeration Replacing Pure Oxygen
Pure oxygen was to be stored on-site and fed after the chlorine contact
chamber to add dissolved oxygen to the plant effluent.
Little head loss was available for the plant effluent, but sufficient head
loss was available for a cascade type aeration chamber immediately after the
chlorine chamber.
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PROCESS EQUIPMENT
Chemical Feed
CHEMICAL FEED ' -J ' "
Consolidate Lime Feed Systems
A 4 mgd facility was being expanded by 14 mgd, but. because of site limita-
tions there would be two distinct plants on the site. Lime feed systems
were proposed to"' control pH prior to nitrification, and separate lime stor-
age and feed systems were proposed for the "old" plant and the "new" plant.
The proposed concept was to utilize the lime storage and feed facilities for
the plant expansion as a centralized lime feed system for the entire site,
and to convey slaked lime from the cejrbral facilities by a series of open
channel troughs to the "old." . r .
Use Larger and Fewer Lime Feeders ; .,/,,'-,;-. ... * ......
Eight lime storage silos, each with 3750 cubic feet of storage capacity were
in the original 'design. A separate lime feeder was utilized for each of the
silos. ,..-.... . . ....''
It was proposed that the silo capacities be increased from 3750 cubic feet
to 5000 cubic feet each, and that the number of silos be decreased from 8_ to
Bulk Storage and Handling for Chlorineand Sulfur Dioxide
In the original design, the disinfection system included the use of ton
cylinders for chlorine and sulfur dioxide.
Recognizing the possible unreliability of the original concept the proposed
concept recommended using a safer more economical bulk storage and handling
of these chemicals rather than ton cylinders.
Eliminate Lime Slurry Feeders . , -.
~From a lime slaker, lime slurry was conveyed to a mix tank and then to four
smaller tanks. Two dual head metering pumps were used to feed from the four
smaller tanks to four application" points.
One large lime slurry tank complete with mixer was proposed to replace the
original system of the mix tank and the four individual tanks. A circula-
tion loop would be set up and fed by recirculation pump. At each of the
lime discharge points, control valves would be used to control the rate of
lime addition. The recirculation loop, recirculation pump, and the control
valves-replace the metering pumps.
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PROCESS EQUIPMENT
Chemical Feed
Purchase Carbon Under a Separate Contract
The original design obtained carbon for charging the carbon adsorption sys-
tem under construction contract.
The proposed concept would let a separate contact under separate bid for
purchase of carbon.
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PROCESS EQUIPMENT
Sludge Collection.
SLUDGE COLLECTION - -S^-:.--;
Replace Chain Drag Sludge Collector with a Traveling Bridge Sludge Collector
Twelve clarifiers were utilized for removal of 1st stage biological sludge,
each clarifier being 15' wide. Sludge collection was by chain drag units,
one for each 12 basins, to hoppers at the influent end of the. basins. Sepa-
rate air lift pumps were used for sludge removal from each basin.
The proposal was for elimination of the chain drag units and the air lift
units, and substitution of a traveling-bridge type sludge collector. Addi-
tionally, the number of clarifiers was to be reduced from 12 basins 15' wide
to 6 basins 30' wide. The traveling-bridge mechanism which was proposed
would be adapted to operate on two of the 30' wide clarifiers at the same
time. Submerged perforated pipe weirs were recommended for effluent collec-
tion instead'of the original "v"-notch weir and trough system.
Use Non-Metallic Chains in Primary Clarifiers
The original concept utilized cast iron chains and redwood flights.
The proposed concept recommended that non-metallic chains be utilized as a
substitute for the cast-iron chains.
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PROCESS EQUIPMENT
Sludge Thickening
SLUDGE THICKENING
Reduce Number of Gravity Thickeners
Four gravity sludge thickeners, each 45 feet diameter with a 10 foot side-
water depth were used in the original design concept.
Reduction of the number of units from four to two was proposed, with the
diameter of the thickeners increasing from 45 foot to 60 foot diameter
thickeners being used in the proposal.
Rearrange Dissolved Air Flotation Units
Two dissolved flotation thickeners were arranged with a 14' wide gallery
located between the thickeners. This gallery contained all the drive units,
thickened sludge pumps, and a thickened sludge storage tank.
Elimination of the gallery between the units and use of a common wall
between the units was proposed. A much smaller gallery was constructed at
one end of the units to contain the pumping equipment, and the sludge
storage tank was eliminated. The proposal substantially reduced the required
building floor area, as well as the quantity of required piping.
Change Bottom Slope of Primary Clarifier
Originally, the primary clarifier was intended to provide both clarification
and sludge thickening to approximately a 5% solids content. To accomplish
this degree of thickening a dual-slope bottom was used for the clarifier,
and polymer was planned to be used in subsequent sludge treatment if 5%
solids could not be obtained in the clarifier.
The proposed concept recommended modification of the clarifier bottom to a
constant slope bottom and the addition of a separate gravity sludge thick-
ener. The proposal was based upon the anticipated advantages of better over-
all clarifier operation, and a greater likelihood of achieving a 5% solids
concentration in the thickener than in the clarifier. A sludge thickener
should more consistently produce a 5% solids concentration sludge, thereby
reducing polymer costs.
Use Gravity Thickeners For All Sludge
A pure oxygen activated sludge plant was designed to use gravity thickening
for the primary sludge and dissolved air flotation (DAF) for the pure oxygen
secondary sludge. The anticipated concentration for the DAF product was 4%
solids. Both the gravity thickeners and the DAF units were enclosed in a
building.
The proposed concept recommended using gravity thickeners for thickening
both the primary and secondary sludge. Although gravity thickening of bio-
logical secondary sludge is difficult, the proposal was based ' upon the
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PROCESS EQUIPMENT
Sludge Thickening
experienced ability of pure oxygen activated sludge to be thickened to 4%
using gravity thickeners. The building included in the original proposal was
elintinated.
Convert Gravity Thickeners to Air Flotation Thickeners ,',.",'
The original concept proposed to construct two air flotation thickening
tanks with a total of 1600 square feet of area for .concentration of waste
activated sludge.
In the proposed concept two of the existing gravity thickeners, with a tptal
surface area of. 2500 square feet, would be converted and used as air flota-
tion thickeners.
Thickening of Waste Activated Sludge (with chlorine addition)
The original concept proposed use of air flotation to concentrate waste
activated sludge. . ,
In the proposed concept existing 40-foot diameter gravity thickeners would
be used to thicken the waste activated sludge. Chlorine was to be used to
aid in the thickening process. It was estimated that approximately 100 rag/L
of chlorine would be required for the thickening process.
Eliminate Pump Suction Control Valves and Magnetic Flow' Meters '
The original design balanced the sludge withdrawal rates from each clarifier
by utilizing butterfly valves, and magnetic flow meters with motor operators
for the butterfly valves. The sludge return rate to the aeration tank would
be controlled by variable speed return activated sludge pumps.
The proposed concept would use an arrangement of telescoping valves and a
headbox arrangement at each set of clarifiers. By adjusting, all telescoping
valves to the same elevation equal quantities of sludge would be withdrawn
by hydraulic displacement from each clarifier. This rate would be adjustable
by raising and lowering the telescoping valves. Each telescoping valve would
be located in a separate compartment in the headbox and discharge over a
V-notch weir so that the flow balance could be checked and adjusted as
required. Figure 26 shows sketches of the original and proposed concepts.
Consolidate All Thickening at One Location : ;
" - "''",- f -
The design of the treatment facilities included a wastewater treatment plant
'at one site and a separate solids handling facility at another site. In the
original design, the waste activated sludge was thickened in ?a dissolved air
flotation unit on-site at the wastewater treatment plant before pumping to
the solids handling plant. A 3-1/2% solids mixture of primary and thickened
waste activated sludge was to be pumped to the solids handling plant.
. The proposed concept recommended no thickening at the wastewater plant.
Instead, a 1.8% solids mixture of primary and waste activated sludge would
be pumped directly to the solids handling plant for thickening. This system
1 ' ' - ":\- - - .75 ' -' - .:... . /
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PROCESS EQUIPMENT
Sludge Thickening
16
S" -
5H3 SKB
MAGMETER{14)
B.V. CONTROL W/
MOTOR OPERATOR
#2
16
ฑ-E3
16
RAS PUMPS
RAS PUMPS
16
ORIGINAL CONCEPT
WEIR BOX
V-NOTCH WEIR
V-NOTCH WEIR (TYP)
->
1
TELESCOPING VALVE
RAS PUMPS
RAS PUMPS
PROPOSED CONCEPT
Figure 26. Replace control valves with telescoping valves.
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PROCESS EQUIPMENT
'Sludge Thickening
eliminated the need for thickening at the wastewater treatment plant and
consolidated all thickening at one single location.
Reduce Dissolved Air Flotation Size
In the original design, a single 700 sq ft dissolved air flotation (DAF)
unit was provided at the facility. The unit was sized to accommodate peak
flows of 2.3 times the average daily flows.
The proposed concept recommended reducing the size of the DAF thickener to
300 sq ft and providing a polymer feed system. The polymer feed system would
be used only during peak flow conditions which were estimated to occur only
about 5% of the time.
Eliminate Gravity Thickeners
The original concept provided gravity sludge thickeners for thickening pri-
mary sludge. Included with the thickeners was a thickened sludge holding
tank and a pumping station.
The proposed concept eliminated the gravity thickeners and increased the
capacity of the vacuum filters and also increased the size of the mix and
holding tanks associated with the vacuum filters.
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PROCESS EQUIPMENT
Sludge Dewatering
SLUDGE DEWATERING
Eliminate Covers from Sand Drying Beds
The original design concept included sand drying beds with covers.
The proposed concept suggested using the sand drying beds, but deleting the
covers and thereby providing easier access to the beds. Drying, time would be
decreased during summer months but would increase during poor weather.
Add Heat Treatment for Sludge Dewatering
In the original concept, sludges from the primary and biological processes
required chemicals in the dewatering process. The dewatered sludge was
hauled to a remote incinerator.
In the proposed concept, heat treatment would be added to the dewatering
process, thus increasing the percent solids and decreasing the amount of
sludge that needed to be hauled to the remote incinerator.
Substitute Filter Presses for Vacuum Filters Prior to Incineration
In the original concept for the sludge handling system, vacuum filters were
used to dewater the sludge prior to multiple hearth incineration. The orig-
inal heat balance calculations used 20 to 25% moisture for vacuum filter
dewatered sludge.
In the proposed concept, vacuum filters would be replaced by filter presses
with a planned capability of producing 40% solids filter cake. The increased
solids concentration would reduce or eliminate supplemental fuel required by
the incinerator.
Eliminate Waste Activated Sludge Centrifuges
In the original concept centrifuges were used to thicken waste activated
sludge prior to aerobic digestion. The system employed one unit with another
standby centrifuge for either this operation or for thickening anaerobic
primary sludge digested.
In the proposed concept no centrifuges were provided and the waste activated
sludge was aerobically digested directly without thickening. The existing
aerobic digestion facilities provided 6-1/2 days digestion under these oper-
ating conditions.
Use Conveyor Belt for Dewatered Sludge in Place of Pumps
The original concept indicated that dewatered sludge cake from a belt filter
press was to be pumped to a truck loading facilities and then to be hauled
to a landfill. The type of pump was unspecified.
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PROCESS EQUIPMENT
Sludge Dewatering
Since the 25% to 35% moisture content of "the dewatered sludge from the belt
filter press would be very difficult to pump, the proposed concept recom-
mended that the dewatered sludge be transported by a conveyor belt.
Use Waste Pickle Liquor in Lieu of Ferric Chloride
The original concept was to use a ferric chloride solution for one of the
chemical conditioning agents.
The proposed concept would be to obtain free waste pickle liquor from a
local steel mill.
Use Belt Filter Press with Polymer Conditioning in Lieu of Plate and Frame .
The original concept utilized a plate and frame filter with ferric chloride
for sludge dewatering. -
The proposed concept used a belt filter press with polymer conditioning. The
proposed concept simplifies operation and provides greater visibility of
operating conditions.
Use Precast Concrete Walls for Sludge Drying Beds
The original concept used sand drying beds. Walls for the various sludge
drying beds were to be constructed of cast-in-place reinforced concrete.
The proposal was to use precast concrete panels as a replacement for the
original walls. The precast panels would be maintained in position by pre-
cast supports. A sketch of the proposed-concept is shown in. Figure 27.
Design Sludge Dry Beds for Mechanical Sludge Removal
Sludge disposal by liquid application on a golf course was planned as the
primary method of disposal. When this primary method was seasonally unavail-
able, on-site sand drying beds were to be utilized. Because the sand drying
beds were to be used only periodically, they were designed for manual sludge
removal. The original design was for drain tile covered by a sand and gravel
blanket. -. - -~ '". - " - : ^
Beds suitable for sludge removal by a .front end loader were proposed.
Asphalt was proposed over a base course, and the asphalt sloped to a six
inch concrete drain tile running down the center of the- bed. The proposed
design would allow use of mechanical equipment. Sketches of the original and
proposed concepts are shown in Figure 28.
Substitute Belt Filters for Vacuum Filters
Sludge dewatering was to be performed using vacuum filters, with sludge con-
ditioning by lime and ferric chloride. .
Replacement of the planned vacuum filters with belt filters was proposed.
The conditioning chemicals would also be switched, from lime and ferric
chloride to polymer.
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PROCESS EQUIPMENT
Sludge Dewatering
POURED CONCRETE
ORIGINAL CONCEPT
PRECAST SUPPORT
E
PRECAST PANEL
8'-0"
PROPOSED CONCEPT
Figure 27. Use precast concrete walHs.
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PROCESS EQUIPMENT
'Sludge Dewatering
GRAVEL
UNDERDRAW
ORIGINAL CONCEPT
3" THICK. 1/4'TO 1/2* GRAVEL
2" Ml No THICK ASPHALT
4 THICK COARSE SAND
2" LEVELING . COARSE
6"THICK BASE. COARSE
6"CONC. OPEN
JOINT DRAIN TILE
PROPOSED CONCEPT
Figure 28. Design sludge drying beds for mechanical equipment
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PROCESS EQUIPMENT
Sludge Stabilization
SLUDGE STABILIZATION
Replace Anaerobic Digestion with Stabilization Lagoons
Originally, digestion and thickening was planned for sludge stabilization
prior to placing it in a storage lagoon. Ultimate sludge disposal from the
storage lagoon was by hauling to landfill.
The proposed concept recommended deleting the digestion and thickening sys-
tems and utilizing a series of anaerobic/aerobic ponds to store and stabil-
IzlTthe sludge. As the ponds were filled with sludge, they would be taken
out of service and the sludge allowed to dewater and dry. The, sludge could
then be loaded and hauled to a landfill site. The lagoon sludge stabiliza-
tion system would be used to provide the detention time required to
'stabilize the waste sludges from the plant as well as to provide adequate
surface oxygen in the ponds to minimize odors.
Replace Gas Mixing System with Mechanical Mixers
Originally, the anaerobic digesters were provided with a gas mixing system
which did not provide complete mixing.
It was recommended that a mechanical mixing system be used in place of the
gas mixing system. The proposed system provided better mixing for the same
horsepower input, required less maintenance, consumed less energy, and
required less building space than the original design. A schematic of the
original and proposed mixing systems are shown in Figure 29.
Reduce Digester Size
In the original design, two anaerobic digesters were sized to provide a 27^
day detention time, which would give a 13-1/2 day detention time with one
digester out of service.
The proposed concept recommended reducing the size of the digesters to pro-
vide a 14-day detention time, which corresponded to 0.11 Ib VS/CF. This
loading was considered well within the range of accepted time and loadings
for a high rate digestion. Backup sludge holding capability was available at
the plant if one of the digesters had to be taken out of service.
Delete Waste Activated Sludge Digestion and Dewater Directly
The original design combined primary sludge with waste activated sludge for
treatment in anaerobic digesters. The combined anaerobic digested sludge was
then dewatered on belt presses.
It was recommended that the waste activated sludge be dewatered on the belt
presses prior to digestion. This proposal reduced the required size of the
anaerobic digesters.
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PROCESS EQUIPMENT
Sludge Sta]5iiization~
EXCESS GAS
GAS COMPRESSOR
FLOATING OR FIXED COVER
ORIGINAL CONCEPT
GEAR BOX
MOTOR
TURBINE BLADE
OPTIONAL
UPPER
TURBINE
PROPOSED CONCEPT
Figure 29, Mechanical mixing in anaerobic digesters.
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PROCESS EQUIPMENT
Sludge Stabilization
Provide Aerobic Digestion for Secondary Sludge
The original design concept for sludge stabilization 'involved thickening the
waste activated sludge from the secondary settling basin and then anaero-
bically digesting it.
The proposed concept recommended using anaerobic digestion for the primary
sludge and providing aerobic digestion for stabilizing the waste activated
sludge.
Movable Gas Holder Cover to Replace Fixed Cover on Primary Digester
The original design included a fixed cover on the primary digester and a
high pressure (65 psi) sludge gas storage tank with three gas compressors.
The proposed concept recommended eliminating the gas storage tank and pro-
viding a movable cover on the primary digester. Gas required for digester
heating and for use in the digester control buildings would be furnished
from digester storage.
Insulate Anaerobic Digester Covers
Anaerobic digesters were designed with steel plate dome covers.
Addition of a 2-inch sprayed-on foam layer was proposed on top of the steel
cover to provide further insulation to the digesters.
Digester Heating with Hydrogen Gas
The plant utilized on-site hypochlorite generation to produce hypochlorite
for effluent disinfection. Hydrogen gas which was produced during the hypo-
chlorite generation was planned to be wasted.
Use of the hydrogen gas to replace digester gas used for digester heating
was proposed. Hydrogen gas would be used along with the digester gas in a
boiler to heat hot water. The digester gas which was saved by the substitu-
tion could then be used in an engine generator to generate electrical
power. :
Earth Berms Around Anaerobic Digesters
Anaerobic digesters were designed with a 25 foot wall height, 10 feet below
ground and 15 feet above ground. 16-inch thick concrete walls were used with
no other form of insulation. ... . - .
'''-. f "''' ' *'f M '' ป .,. , '':''ป' *
Use of earth berms to insulate the digesters was proposed to lower.. digester
heating requirements and provide a more aesthetically pleasing plant site.
Eliminate Anaerobic Digester Supernatant Tank
The original concept was to construct a holding tank to store anaerobic
digester supernatant and to feed it back to the headworks at a controlled
rate.
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PROCESS EQUIPMENT
Sludge Stabilization
In the proposed concept the supernatant holding tank was deleted, assuming
that the secondary digester could be considered as a holding tank.
Eliminate Aerobic Digester and Use Existing Anaerobic Digesters
In the original concept, centrifuges were to be used to thicken waste
activated sludge. Existing primary clarifiers and aeration basins were to be
converted to aerobic digesters for digestion of the centrifuge thickened
WAS. Primary sludge was to be anaerobically digested in existing anaerobic
digesters.
In the proposed concept the same centrifuge thickening scheme was to be
retained, but the existing anaerobic digestion capacity was to be used for
both the primary sludge and the centrifuge thickened WAS.
Substitute Boilers in Place of Supplemental Solar Panels
The original concept utilized a solar panel hot water system to furnish sup-
plemental heat to the digesters.
The proposed concept would provide more reliable conventional oil fired
boilers and completely eliminate the solar panels.
Include Conical Portion of Anaerobic Digester in Effective Volume
Anaerobic digesters were 105-feet in diameter and had a bottom slope of 1:1.
Detention time in the anaerobic digesters was calculated using only the
cylindrical portion of the digester, and did not count the conical portion.
The proposed concept recommended that the conical portion be included as a
usable portion of the digester capacity and in calculating the detention
time of sludge in the digester. This would,allow the digester diameter to be
reduced from 105 feet to 85 feet.
Substitute Mechanical Aeration for Diffused Aeration in Aerobic Digesters
A activated sludge plant was to aerobically digest thickened primary and
waste activated sludge. The original concept- was to use diffused aeration to
supply air to the aerobic digesters.
The proposal was to utilize surface mechanical aerators to replace the
diffused aeration system.
Reduce Number of Digesters and Use Floating Covers
The plant was to be designed using three anaerobic digesters, each 90 feet
in diameter and 24 feet SWD. Two feet of freeboard was provided, and fixed
concrete covers supported on concrete were used on each digester. Gas stor-
age at 50 psig was provided in a gas storage Sphere for 1 day of gas
production at 50 psig.
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PROCESS EQUIPMENT
Sludge Stabilization
Reduction of the number of digesters from 3 to 2 was proposed, along with
elimination of the gas storage sphere. Gas storage was proposed to be
accomplished by the addition of steel floating gas holding covers for both
digesters. The new digesters would be 110 feet in diameter and have 24 feet
of SWD.
Eliminate Cranes from Anaerobic Digester Roofs
Three 95 foot diameter anaerobic digestors with fixed concrete covers were
utilized for sludge stabilization. Heating of the digesters was accomplished
using vertical internal heat exchangers placed into the digesters through
the roof. Each digester was provided with a roof top crane for removal of
the heat exchangers when required.
The proposal was for elimination of the permanent cranes, and use of rental
cranes or use of temporary false work when removal of the heat exchangers
was required. Removal was estimated to be once every five years or less,
based on past experience.
Substitute High-Rate Anaerobic Digesters for Low-Rate
The original concept used two gravity thickeners for a combination of pri-
mary and rotating biological contactor secondary sludge. The thickened
sludge was to be anaerobically digested using two stage digestion. Two pri-
mary digesters provided a 35 day detention time and they were equipped with
floating covers. Secondary digesters were equipped with fixed covers. The
four digesters and the two thickeners were clustered around a central
building.
The proposed change was to construct three high rate digesters. The total
detention time would be 14 days with two of the digesters in operation and
the third utilized as a holding tank. The three digesters and two gravity
thickeners would be clustered around an enclosed pentagon shaped sludge pump
station and boiler room.
Reduce the Number of Digester Gas Mixing Compressors
The original design called for 5 gas compressors. Each primary digester
would have one operational and one standby compressor and a fifth compressor
was to be used for the two secondary digesters.
In the proposed design, the secondary digester mixing compressor and one of
the standby compressors for the primary digesters were eliminated. When sec-
ondary digester mixing was required, it was proposed to use the standby com-
pressor for that purpose.
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PROCESS EQUIPMENT
SludgeDisposal
SLUDGE DISPOSAL - . , ' ' "''::''.-;.''
Haul Liquid Sludge and Eliminate all Sludge Treatment
The original design concept included aerobic digestion plus sand drying beds
for the first five years of plant operation. Phases II & r II of the treat-
ment facility, .which were to occur sometime after the first five years,
included aerobic digestion plus vacuum filtration.
, The proposed concept recommended hauling liquid waste activated sludge and
primary sludge directly to a treatment plant 20 miles away and completely
eliminating all sludge treatment. . ". -
Eliminate Sludge Storage Tank
The regional solids handling facility included a holding tank to receive
sludge which was hauled from other treatment facilities. A pump station was
provided to transfer sludge from the holding tank directly to the
digesters.
The proposed concept recommended pumping sludge directly from the trucks to
the anaerobic digesters, eliminating the need for the sludge storage tank
since the daily volume of sludge to be hauled in was only a very small per-
centage of the total sludge in the digesters. .'"'-
Use Pipe Line Rather Than Trucks to Transport Sludge ', ' :.. -',.
In the original concept the digested sludge was hauled using 5500 gallon
trucks to an ultimate disposal site approximately five miles from the treat-
ment plant site. About 11 truck loads a day were required at design capacity
of the plant.
In the proposed concept an 18-inch pipeline was used to transport a 4%
solids sludge to the ultimate disposal site. .
Use Throttling Vanes in Place of Variable Speed Drives on Induced Draft'Fans
The original concept proposed to use four induced draft fans on sludge
incinerators. The fans were proposed to have variable speed drives to pro-
vide adjustable air inputs. ~ '
In the proposed concept two ID fans were used with throttling ID fan inlet
- vanes rather than variable speed drives.
Preheat Incinerator Combustion Air
The original concept utilized conventional combustion air injection without
preheating.
The proposed concept would install a type 304 stainless steel heat exchanger
in the bridging between the incinerator and scrubber thereby preheating the
87
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PROCESS EQUIPMENT
Sludge Disposal
combustion air to 800 degrees Fahrenheit prior to injecting air into the
furnace.
Eliminate Incinerator Ash Storage Basin
An impingement type scrubber was planned to be used on a sludge incinerator,
with the flow from the scrubber passing to a storage basin. After settling,
water from the basin would be returned to the scrubber system.
Use of a cyclone separator was proposed as a substitute for the ash storage
basin. Water from the impingement scrubber would be pumped by a booster pump
to the cyclone separator, and after separation the clarified water would be
recycled and reused in the impingement scrubber. Ash would be disposed of
identically in either scheme.
Eliminate Sludge Storage Bins
The original design included sludge storage bins to hold sludge after being
removed the sludge drying beds.
The proposed concept recommended eliminating the sludge storage bins and
hauling the sludge directly to a landfill
88
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SITE LAYOUT
Eajr.thwo.rJc
,-,.--. . ! -.-..-...-.. .:,. CHAPTER 4 . ':-.::.. -./... ...'":
V . EARTHWORK . ' ' . ...:..-..-...
Use Reclaimed Rock From on Site Excavation for Construction of Breakwater
The original concept proposed sheet steel piling for a 700 foot long coffer-
dam at an existing lagoon.
The proposed concept would utilize rock, excavated.. from another part of the
construction site, to cover the surface of the cofferdam. Additional
material would be required to make the cofferdam impervious.
Reduce Final Grade
This project was to be constructed in a swampy area, and costly fill mate-
: rial would have been required to raise the entire site. .
The proposal was to lower theentire site elevation (not the structures) by
1* . This would make the "entire site more prone to flooding, but would not
make the treatment facilities themselves more suscepible to flood damage.
Some redesign would be necessary to implement the proposal.
Reorient Plant and Change Site Grading to Eliminate Handrails '
In the original concept, on-site influent piping was conveyed through sev-
eral hundred feet of pipe tunnel before reaching the" .influent structure.
Also, finished grades were 6- to 12-inches below tank 'tops', and aluminum
handrails were used around each of the basins.
The proposed concept recommended reorientation. of the 'plant to put the infl-
uent structure closer to the location where the influent sewer entered the.
plant site.This reorientation also eliminated "back and forth" conveyance
of flows on the plant site. Another modification was to. lower the finished
grade 30- to 36-inches below the top of the various structures, thereby
eliminating the need for the handrails around the basins.
Eliminate Retaining Wall and Regrade ....';
The original concept proposed a retaining wall to be located between a pro-
cess building and the roadway.
The proposed concept would eliminate the retaining wall and regrade the
slope.' -' - -.. '._ -.'- ,: .
Use Precast Panels Instead of Retaining Wall
In the original concept a retaining wall was used to support an earth
embankment. Construction was to be a standard cantilevered wall with back-
fill behind the wall and a lower finish grade in front of the wall. Along
the same area sheet piling was to be placed during construction and then
later cut off and replaced by the retaining wall.
. ' 89 .:.-.,;...- : ..-'..-
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SITE LAYOUT
Earthwork
In the proposed concept the steel piling would remain in place and precast
concrete panels are set behind the piling flanges to form a retaining wall,,
Figure 30 shows sketches of the original and proposed concepts.
Use Open Cut Excavation in Lieu of Coffer Dam Construction
A large interceptor pumping station was planned to be constructed using
pilings, bracing, excavation, and deep well dewatering. EJcav-atLon would be
using a clamshell bucket
The proposed concept recommended elimination of the complex bracing, pilings
and dewatering by using open cut excavation.
90
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SITE LAYOUT
Earthwork
CANTILEVER WALL-
EXCAVATE &
BACKFILL
CUT-OFF H-PILING
II
II H
ORIGINAL CONCEPT
PRECAST CONC PANELS
H-PILING
PROPOSED CONCEPT
Figure 30. Replace retaining wall with precast panels in H-piles.
91
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SITE LAYOUT
Roads
ROADS
Use Narrower Entrance Road
The original concept used two 24-foot divided entrance roads with complete
curbing and gutters.
It was proposed to eliminate one of the divided roads, and eliminated the
curb and gutter from the remaining road.
Delete Roads Required for Future Expansions
The original concept included roads required for not only the initial phase,
but also all subsequent phases of the treatment facility.
Deleting the roads required for future expansions of the treatment facility
was proposed. This change would not affect traffic flow or access for the
initial phase.
Use Filter Fabric Under Paved Areas
The site for the treatment facility had previously been a landfill, and the
soils report indicated the probability of continued settlement. A minimum of
2-foot of sand and gravel base material was recommended for plant roads by
the soils report, and in some locations, up to 4-foot of sand and gravel
base material were recommended.
The proposed was to excavate to 20-inches below finished grade of all paved
areas and to install fabric material prior to spreading the base material.
Reduce Roadway Width
The original concept provided a 20 foot wide paved and curved access road
around the perimeter of the plant.
The proposed concept reduces the paved width to 12 feet with one-way
traffic.
Change Road Paving
The original concept proposed a paved access road around the perimeter of
the treatment plant. The pavement consisted of a 10 inch subbase, six inch
processed aggregate base, and three inch paved road section.
In the proposed concept oil treated gravel would be used on the access roads
around the plant perimeter. The gravel base would be 12 inches of crushed
gravel.
92
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SITE LAYOUT
Roads
Revise Site Roadways and Reduce Roadway Width
In the original concept an extensive network of various width of roadways,
multiple parking areas, and numerous paved turn around or access areas for
the various buildings of the treatment units were used.
In the proposed concept roadway widths were reduced from 24 feet to 18 feet,
which was considered ample for the low speed travel which would be required
at the plant site. The parking areas were also revised and reduced, but
still remained functional.
93
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SITE LAYOUT
Piping
PIPING
Simplify Return Activated Sludge Flow Balancing Scheme
In the original concept, return activated sludge (RAS) flow would be split
by an instrumentation based ratio scheme utilizing flow meters and throt-
tling valves to determine the relative proportions of sludge to each aera-
tion basin. The ratio to be utilized would be entered by the operator.
Normally, 1/2 - 1/2 for the first stage aeration and 1/3 - 1/3 - 1/3 for the
second stage aeration.
In the proposed concept, RAS flow would be routed to the aeration basin
influent splitter boxes and split with the influent, thus eliminating the
complicated instrumentation system. Figure 31 shows schematics of the orig-
inal and proposed schemes.
Eliminate Pipe Gallery
The original design proposed air^pipe gallery along the end of the aeration
tank.
The proposed alternative was to eliminate the gallery and to either bury the
pipes or to support them from exterior walls above grade.
Mpdify ScumHandling Systems
Scum from secondary clarifiers and backwash water from tertiary filtration
facilities was to be transported to a reclaimed water clarifier. Settled
material from the reclaimed water clarifier would then go to a waste sludge
pump station, and scum off the top of the clarifier would be pumped to the
Sludge Disposal area for further concentration and incineration. All lines
which were to carry scum or the scum/backwash were lined to prevent build-up
of scum in the pipe.
The proposal was based upon both eliminating the dilution of scum with
filter backwash water and then reconcentrating the scum in the reclaimed
water clarifier, and eliminating as much piping as possible, particularly
lined pipe. Based on these two concepts, the following changes were pro-
posed: eliminating the reclaimed water clarifier, pneumatically ejecting
scum from the final clarifier directly to the Sludge Disposal Area, elimina-
ting the separate lined pipeline for scum/backwash, and conveying backwash
water directly to the plant drain through an unlined pipe.
Use PVC to Replace Ductile Iron Pipe
Potable and non-potable water systems between 3-inch and 8-inch were orig-
inally designed to be of ductile iron pipe.
Class 160 PVC (ASTM D2241) was proposed as a replacement for the ductile
iron pipe.
94
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SITE LAYOUT
Piping
'RIMARY
FFLUENT
INTERMEDIATE
CLARIFIERS
RETURN ACTIVATED SLUDGE
MAGNETIC FLOW METER &
THROTTLING VALVE ( TYP)
2ND STAGE
AERATION
TO FINAL,
CLARIFIERS
-CH&P
RETL
-*ป. '
.
JRN NITRIFIED SLUDGE .... : :.
ORIGINAL CONCEPT
. 2ND STAGE
AERATION
1ST STAGE
AERATION
FLOW SPLITTER
'-BOX---
PRIMARY
EFFLUENT
."-w
TO FINAL
CLARIFIER!
RETURN NITRIFIED SLUDGE .
SLUDGE
PROPOSED CONCEPT
Figure 31. Simplify return activated sluc.ge flow balancing scheme.
95
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SITE LAYOUT
Piping
Simplify Secondary Clarifier Flow Distribution and Piping
Five equal diameter circular clarifiers were to be utilized in the original
concept. Flow to the clarifiers was to be divided equally by using a knive
gate valve and a flow meter for each clarifier. After flow measurement,
42-inch pipes conveyed flow to each clarifier with the nearest clarifier
being 45* from the distribution vault and the furthest one being 230' away.
A simplified approach was proposed for flow splitting between the five
clarifiers. The knife gate valves and flow meters were eliminated, and were
replaced by weirs and slide gates. Piping to the clarifiers was changed from
the original 42-inch size, the proposed sizes to be a function of the
distance to each clarifier. In the proposal, distribution pipe sizes ranged
from 36-inch to 48-inch.
Reduce Size of Return Activated Sludge Pipeline
Originally, 1200 feet of 36" diameter return activated sludge line capable
of handling a peak return sludge flow of 15 MGD was included in the plans.
An average operating condition for the pipeline was 7.5 mgd.
Concern was expressed over solids deposition in the pipeline. Scouring
velocity probably would not occur at the 7.5 mgd flow rate in the 36" pipe.
Analysis indicated that a -24-inch- pipe should be used to create scouring
velocity at the 7.5 mgd flow rate. Power costs were increased somewhat by
use of the smaller pipe.
Splitting of Return and Waste Activated Sludge
A flow splitting chamber was used at the secondary clarifiers to split the
return activated sludge (RAS) and the waste activated sludge (WAS). Separate
parallel pipelines were then used for about 800 feet from the flow splitting
chamber to the dissolved air flotation thickeners (WAS piping) and to the
head of the aeration basins (RAS piping).
i
/
Elimination of the RAS/WAS splitting chamber was proposed and a single pipe-
line was to be used to the DAF units. RAS flow was to be metered from this
pipeline to the aeration basins using two metering pumps.
Replace Tunnels With Buried Structural Slab
The plant under consideration was to be constructed on the site which had
previously been a sanitary landfill. This necessitated the use of piling to
support the tunnels which provided access between the treatment processes
and in which piping was located. Because of the possibility of methane gas
seeping into the tunnels, a positive ventilation system and a hazard-warning
system were required.
96
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SITE LAYOUT
Piping
The proposed concept recommended use of a buried structural slab in place of
the tunnels. Piling would still be required because of high groundwater and
poor subsurface conditions, and the structural slab would have to be
.attached to the piling. The proposal would eliminate heating, lighting,
' . ventilation and drainage for the tunnels.
Substitute Steel for Ductile Iron Inside Piping
The original concept used ductile iron pipe with flanged fittings on all
process scum, sludge, air, potable water and non-potable water piping.
Standard steel piping with welded fittings and sleeve type joints was pro-
posed as a substitute.
Relocate Influent Force Main, Outfall, and 36" Storm Drain Into a Common Trench
In this study, the treatment processes and plant layout could not be
changed, but relocation of the influent force main, the outfall, and an
on-site storm drain was identified as" an :area of cost savings. The plant
site was crossed completely or partially by an influent force main, the
plant outfall, and a storm drain. Each of these facilities was to be
installed separately in its_ own trench. . ,
The proposed concept recommended relocation of these facilities so that use
of a common trench was possible for much of their length. The original and
proposed layouts are shown in Figure 32. ,
Use Class IV Reinforced Concrete Pipe for Final Effluent Piping
The original concept proposes to use prestressed concrete cylinder pipe for
the effluent piping. -'_' .
In the proposed concept, Class IV reinforced concrete'pipe would be substi-
tuted for the original concept.
Revise Air Piping Material
In the proposed concept all air piping was to be stainless steel whether it
is buried or exposed to the atmosphere. ,
In the proposed concept the exposed outside piping would remain stainless
steel but all other piping would be carbon steel or cast iron.
Use Open Channel for Storm Flow Instead of Storm Drain ,
The original concept calls for the construction of two 60 inch storm drains
to intercept an existing storm drain.
In the proposed concept, the two 60-inch pipes would be used only where open
channel flow was not possible. An open channel would be used for the
remainder of the diversion.
97
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SITE LAYOUT
Piping
n
OOnOO]
O O O Q
GC-
P Q Jjo o
ORIGINAL CONCEPT
r
7""
n
O O
d
,O
O JJQ o
LEGEND
36"STORM DRAIN
54" OUTFALL
54" INFLUENT FORCE MAIN
18" STORM DRAIN
PROPOSED CONCEPT
Figure 32. Reduce length of yard piping.
98
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SITE LAYOUT
Plpln g -
Delete Pipe and Gates to Drain Head End of Aeration Tank
Aeration basins in the plant were divided into four stages to allow some of
the aeration basin tankage to be taken out of service in the winter 'months.
Gates were provided at both ends of the aeration basins, even though only
the later stages of the aeration basins would be taken out of service in the
winter. ' " ' : ." ' "" "\. " '" ".'- - . ' " '
In the proposed concept all drainage would be removed from the tail end of
the basin, eliminating approximately half of the interconnecting pipe and
four sluice gates. A sketch showing the deleted piping is in Figure 33.
Relocate Splitter Box for New Secondary Clarifiers ,
Two new secondary clarifiers were to be added to a plant which had four
existing clarifiers. Flow to the existing clarifiers was, split by a four-way
splitter box. The original concept called for the modification of this
four-way splitter box into a six-way splitter box which would serve both
existing and new clarifiers.
'Because the new clarifiers were not in the same area as the existing clari-
fiers and because the pipe to the existing four-way splitter box passed
adjacent to the new clarifiers, it was proposed that the flow for the new
clarifiers be split out ahead of the existing four-way splitter box. There-
fore, the new splitter box would split the. flow for the two new clarifiers,
and the flow to the existing four-way splitter box. The proposal resulted in
a savings of piping, and eliminated modification of the existing splitter
box. Sketches of the original and proposed concepts are shown in Figure 34.
Relocate Sludge Pumping Station More Centrally to Multiple Clarifiers
Separate waste sludge arid return sludge lines were used from six clarifiers
to the sludge pumping station. Due to the layout of the plant, some of these
pipes were relatively long, and plugging was a potential problem. Horizontal
centrifugal pumps were planned to be used for sludge pumping.
The proposed concept suggested eliminating the long pipe runs by locating a
sludge pumping station between each bank of two clarifiers. Vertical mixed
flow pumps were * proposed for the waste activated sludge, and vertical cen-
trifugal pumps were proposed for the return activated sludge.
Combine Mixed Liquor Suspended Solids Piping
In the'.'" original 'concept, three mixed liquor suspended solids lines were
required. One line was to two existing intermediate clarifiers and the two
remaining lines were to two new intermediate clarifiers>
In the proposed concept, the MLSS piping was combined to the greatest pos-
sible extent. Figure 35 shows a sketch of the ^original and proposed
concepts.
99
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SITE LAYOUT
Piping
GATES
ORIGINAL CONCEPT
J
u
-S
A
ป T
1 * 1 ' 1
rH K i t 1
ERATION
TANK NO. 3
J
[553
^
AERATION
TANK NO, 2
II
tX3
^
EXJ ea
AERATION
TANK NO. 1
15=53
^ B
J
DRAINGAGE PIPING
PROPOSED CONCEPT
Figure 33. Delete drain pipes and qates from head end of aeration basin.
100
-------
SITE LAYOUT
Piping
101
-------
SITE LAYOUT
Piping
1ST STAGE
AERATION
ORIGINAL CONCEPT
1ST STAGE
AERATION
PROPOSED CONCEPT
Figure 35. Simplify mixed liquor piping.
102
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SITE LAYOUT
.Piping
ite Alt
itive Materials for Large Diameter Stainless Steel Air. Headers
The original design concept included using stainless steel air piping for
areas above the primary effluent and mixed liquor channels, and for. piping
in the runs from the blowers to the aeration basin.complex.
By enclosing the mixed liquor in a conduit, the air headers on the edge of
the aeration basin.could be supported on top of the mixed liquor conduit and
would not be exposed to the mixed liquor. Pipe material could then be
changecTfrom stainless steel to some other material such as welded steel
pipe, where corrosive conditions did not exist, use of fusion-bonded epoxy-
coated and lined carbon steel pipe was recommended.
Eliminate Mixed Liquor Distribution Piping
The initial design used piping to distribute mixed liquor to the aeration
basins. ,
It was recommended that the mixed liquor distribution piping be eliminated
and adjustable weirs off the center channel be used for mixed liquor flow
control. -
Revise Chlorine Contact Tank Piping
Larcre diameter buried valves and fittings were originally proposed for the
chlorine contact tank piping. "
Elimination of most of the buried valves and fittings were proposed by add-
-------
SITE LAYOUT
Piping
It was recommended that the discharge pipes be placed above ground to pro-
vide better access and ease of maintenance.
Route Return Flows to Primary Clarifiers Rather Than To Headworks
The plant drain, thickener, supernatant, and filter press filtrate were
piped back to the headworks of the plant in the original design.
The proposed concept recommended routing the return flow piping to the head
of the primary clarifiers rather than to the plant headworks. Plant flow
monitoring was improved because returned flows would not distort influent
flow measurement at the Parshall flumes.
Eliminate Air Pipe Insulation
In the original design, the air blower discharge piping was provided with
insulation.
The proposed concept recommended eliminating the insulation from the dis-
charge pipe because the pipe was not considered to be hot enough to be a
safety hazard.
Piping to Secondary Clarifiers
Flow from rotating biological contactor secondary treatment was to be con-
veyed by four separate pipes to the four secondary clarifiers.
Use of a single pipeline to a splitter box in the center of the four clari-
fiers was proposed. Slide gates would be used in the splitter box to propor-
tion flows between the clarifiers. Figure 36 presents sketches of both the
original and the proposed concepts.
Increase Size of Return and Waste Activated Sludge
A pure-oxygen activated sludge plant was designed with the return activated
sludge and waste activated sludge piping sized for a 2% solids concentra-
tion, based upon on-site pilot studies.
The proposal recommended re-sized sludge piping based upon a solids content
of 1% rather than 2%. One percent solids was cited as being more representa-
tive of operating full-scale pure oxygen plants.
Revise Scum Piping
In the original concept, separate scum piping was used between two inter-
mediate clarifiers and the pump station which housed the scum pumps. Two
scum pumps were provided for each clarifier.
The proposed concept recommended using a common scum line and common scum
pumps. Sketches of the original and proposed concepts are shown in Figure
37.
104
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SITE LAYOUT
Piping
RBC UNITS
2ND CLAR1FIER
ORIGINAL CONCEPT
30 TYP
/ RBC UNITS
f
\
/
/
\
2ND CLARIFIER
PROPOSED CONCEPT
Figure 36. Use single mixed lj3uor pipe to secondary clarifiers.
105
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SITE LAYOUT
Piping
PIA
SCUM PUMPS
PIB P2A
P2B
ORIGINAL CONCEPT
SCUM PUMPS
PROPOSED CONCEPT
Figure 37. Simplify scum handling system.
106
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SITE LAYOUT;
Equipment & Process Layout
EQUIPMENT & PROCESS LAYOUT
Rearrange Sludge Building
In the original concept major modifications to the incinerator were included
for providing the option of operating in a pyrolysis mode. Dewatering equip-
ment would be converted to a filter press so that the combined primary/ sec-
ondary sludge will be of sufficient dryness for autogenous combustion. A
waste heat recovery boiler was also in the design to supplement the existing
. heating system. -. . . .
In the proposed concept the pyrolysis option was deleted. It appeared unjus-
tified since the new dewatering equipment would allow the incinerator to
operate autogenously. !_
Use Tertiary Filter Backwash Water for Incinerator Scrubber Water
In the original concept, two recycle flows were returned to head of the_
aeration basin. The first of these was scrubber water from the incinerators,
which used plant effluent for the original supply. The second of these flows
was tertiary filter backwash water.
The proposed concept recommended using tertiary filter backwash water as the
supply for the incinerator scrubber. This concept eliminated one half of the.
'return flow. A sketch of both the original and proposed concepts is shown in
Figure 38. , - .
Combine Grit Removal and Preaeration in a Single Structure
Grit removal and preaeration were originally designed as separate operations
in separate structures.
The proposed change used an aerated grit chamber to combine grit removal and
preaeration into the same operation and structure.
Reduce Number of Clarifiers From 5 to 4
The plant under consideration was 50 mgd, and in the future was to undergo a
25 mgd expansion. For the initial 50 mqd phase, 5 secondary clarifiers were
used.
Using 4 instead of 5 secondary clarifiers in the 50 mgd phase was proposed
tcT~simplify the addition of the future 25 mgd phase (2 clarifiers) and
result in 6 clarifiers of equivalent, size at ultimate capacity.
Make Site More Compact - -- -
To construct the treatment facility at the site selected, about 65% of the
site would have required dewatering during construction. Additionally, a
rather extensive ditch system would have been required for groundwater ele-
vation control and for stormwater. The original design was costly in
107
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SITE LAYOUT
Equipment & Process Layout
2.5 MOD WATER SOURCE
IS PLANT EFFLUENT
SCRUBBERS
BACKWASH 2.5 MGD FROM
FILTER EFFLUENT
2ป5 MGD AERATION
BASIN INLET
TERTIARY FILTERS
AHEAD OF
AERATION
BASIN
ORIGINAL CONCEPT
BASE CASE PUMP
BASE
TERTIARY FILTERS
BACKWASH 2.5 MGD FROM
PLANT EFFLUENT
AHEAD OF
AERATION
BASINS
- FLOW RECYCLES
THROUGH SECONDARY
UNITS AND FILTERS
PROPOSED CONCEPT
Figure 38. Scrubber water recycle streams.
108
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SITE LAYOUT
Equipment & Process Layout
construction, and the treatment facilities were spread out on the site
substantially. -. ' .
Compacting the plant onto the site was proposed as a means of reducing the
intitial capital cost, site dewatering, road length and the cost of elec-
trical distribution. A secondary benefit was the availability of more land
for future expansion when required.
Relocate Clarifiers Closer to Aeration Basins
A plant service road and a flood control channel were placed between the
primary clarifiers and the aeration basins.
Relocation of the flood control channel and the plant service road were pro-
posed. This allowed the primary clarifiers and the aeration basins to be
located about 30 feet closer together.
Eliminate New Piping Between Secondary Clarifiers and Chlorine Contact Tank
At an existing plant which was being expanded, a box conduit was used to
convey secondary effluent to the chlorine contact chamber. Although the con-
duit could handle the original plant design flow of 27 mgd, it could not
carry the new ultimate design flow of 36 mgd. The design for the plant
expansion abandoned the existing box conduit arid used a new 66-inch diameter
reinforced concrete pipe.
The proposed concept recommended continued use of the existing box structure
until its capacity was reached, and then adding a parallel pipeline at a
later date when future flows were more definitively known.
Modular Design of Equipment
The original design utilized a complex of circular primary clarifiers,
rotating biological contactors, and a complex of circular secondary clarifi-
ers. Primary and secondary sludge pumping stations were in separate loca-
tions, as was the effluent pumping station, process return pumps, and the
control building.
The equipment. was rearranged into a modular concept utilizing rectangular
primary and secondary clarifiers, and channels for conveyance of flows
between unit processes. A common pipe gallery was proposed, and all pumping
facilities were housed in the control building. Figure 39 shows schematics
of the original and proposed systems.
Rearrange Plant Layout
The original concept utilized a spread out concept with little common wall
construction. There was a high degree of "back and forth" conveyance of
flows on-siteป .
109
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SITE LAYOUT
Equipment & Process Layout
PRIMARY CLARIFIERS
CONTROL GATES (TYP)
RBC SYSTEM
MIXED
LIQUOR SECONDARY CLARIFIERS
PIPE
PRIMARY EFFLUENT
DISTRIBUTION CHANNEL
RAW SLUDGE
PUMPING STATION
MIXED
LIQUOR DISTRIBUTION
CHANNEL
RAS & WAS
PUMPING STATION
ORIGINAL CONCEPT
PRIMARY CLARIFIERS
PIPE GALLERY
& ACCESS
/ CONTROL GATES ( TYPJ
RBC SYSTEM \ SECONDARY CLARIFIERS
RAW SLUDGE
PUMPING STATION
UNDER DISTRIBUTION
CHANNEL
t
PIPE GALLERY
AND RAS & WAS
PUMPING STATION
UNDER MIXED
LIQUOR CHANNEL
PRIMARY EFFLUENT
DISTRIBUTION
CHANNEL WITH
GALLERY UNDER
PROPOSED CONCEPT
Figure 39. Modular design of unit processes.
110
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SITE LAYOUT
Equipment & Process Layout
The proposed concept was a more compact arrangement, using about 25% less
land area. Piping requirements were substantially reduced and a high degree
of common wall construction was utilized.
Flow Equalization After Primaries
The- original concept was to construct flow equalization basins ahead of pre-
liminary treatment, which would require mixing and aeration to maintain
suspension of heavy materials.
The alternative is to place the flow equalization after preliminary and pri-
mary treatment. The effect of this change would reduce the number of pump
' stations required from two to one .It would also make the water storage
easier by removing the majority of the grit, screenings and the primary;
sludge. The removal of the heavy loadings prior to equalization also reduced'
the requirements for aeration in the equalization basin. ,
Relocate Air Blower Building to Slab on Grade
In the original concept, an air blower building with four air blowers was
located on the ground floor of an intermediate pump station building. The
, blowers were positioned over the below-grade dry well for a pump station and
because of their location, the blowers'require special structural design to
support them and dampen the associated vibrations. This location also
requires over 200 feet of 42-inch air header pipe to convey the air from the
blowers to the aeration tanks. ,
In the proposed concept the blowers were located in a slab-on-grade build-,
ing, thereby requiring less structural support and .vibration dampening.
This proposed building would be located with a common wall to the new aera-
tion tank which.also can reduce the cost of the building and the length of'
the required 42-inch air header.
Relocate Odor Control Scrubber and Blower to Outside of Building
In the original design, the odor control scrubber and blower were located
within the screening building..
The proposed concept suggested locating the scrubber and blower outside the
; screening building on a concrete pad. This allowed the screening building to
be reduced in size. A sketch showing the original and proposed concepts is
shown in Figure 40.
Ill
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SITE LAYOUT
Equipment & Process Layout
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112
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SITE LAYOUT v: \ ; .
Hydraulics and Hydraulic Gradeline
HYDRAULICS AND HYDRAULIC GRADELINE '
Lower Plant to Lessen Influent Pumping
A new treatment facility was layed put with an influent pumping station, and''
then gravity flow, through the plant into an adjacent river. The plant facil-
ities were located at a high enough elevation to allow gravity flow even
during 100 year flood flow in the river. Accommodation of this gravity flow
condition during, the .100 year flood flow resulted in pumping requirements
which were substantially in excess of normal requirements.
The proposed concept recommended lowering the plant hydraulic gradeline to
an elevation which would allow submergence of the weirs of the final clari-
fier (but not the final clarifier itself) during a' 100 year flood. The pro-
posal resulted in a significant life cycle energy savings. Additional sav-
ings might also result by lowering the plant even further and adding a
standby effluent pumping station for flood situations approaching the 100
year flood.
Reduce Filter Structure Height
The original concept proposed using a 12.75' filter operating depth and 2^_
of filter freeboard to achieve 24 hour filter runs at peak rates.
The proposed concept recommended reducing the filter operating depth to 10'
and the filter freeboard to 1.5'.
Use Flow Splitter Boxes
The original concept provided a flow control structure with flow meters and
automatic butterfly valves to split the primary effluent and return sludge
between the aeration tank pairs. Tlp-S arrangement was alsp used to limit the
flow-to the secondary process, with excess primary influent to be bypassed'
to the chlorination facilities. ;
In the proposed concept two weir-boxes were provided to split flows, one
weir, box for primary effluent and one ' if or return sludge. The weir boxes
would have the capability of splitting the flow either 1/2:1/2 or 1/3:2/3
between the aeration, tanks. Also,, steel bypass launders and weirs would be
provided in the primary tank effluent channel to collect overflow to the
chlorination. ., : .
Lessen Head on Effluent Pumping Station
The original design for a plant included future effluent filtration facili-
ties in the hydraulic profile of the plant. With inclusion of these facili-
ties, a relatively deep effluent pumping station was required. Without,
inclusion of these future facilities,only a relatively shallow pumping sta-
tion was required, and pumping would only be required during flood
conditions in the adjacent river.
113
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SITE LAYOUT
Hydraulics and Hydraulic Gradeline
Since the future requirement for effluent filtration was uncertain, it was
proposed to raise the effluent pumping station to the highest elevation
possible for the first stage plant consbraction. Such an elevation increase
then allowed gravity flow during all times except flood conditions in the
adjacent river, when effluent pumping was required. Overall, eight feet of
elevation was saved.
Grit Removal After Raw Sewage Pumping
The original design located the grit removal, comminution and raw sewage
pumping in a deep gravity fed structure.
The proposal was to place the grit removal and comminution downstream from
the raw sewage pumps, and raising the grit removal and comminution facili-
ties to at-grade.
Raise Elevation of the Influent Screw Pumps
In the original concept, the hydraulic grade line in the pump station
influent pump trough was 5 feet above the top of the screw pump.
The proposed concept recommended raising the bottom elevation of the
influent pump trough by approximately 4' thereby placing the hydraulic grade
line only 1' above the top of the screw. The proposal would shorten the
screw by 8' and reduce the horsepower required from 75 to 60. A sketch of
the original and proposed concepts is presented in Figure 41.
Lower Primary Treatment Processes and Eliminate Influent Pumping Station
The original concept provided hydraulic profile with pumping required prior
to the new primary settling tanks. The primary tanks were located on a high
hillside.to allow for gravity flow through roughing towers with a 24' media
depth, and then to intermediate clarifiers. Effluent from the intermediate
clarifiers was then to be pumped to aeration tanks. During low flows, some
of the intermediate flow was also to be recycled to the roughing towers.
The proposed concept lowered the new primary clarifiers to allow gravity
inflow, thus eliminating the primary pump station. The roughing towers were
ceduced in height by using only 20' of media depth and lowering the base of
the towers to allow for gravity flow into the towers from the primary clari-
fiers. This new hydraulic profile only required pumping of roughing tower
effluent to the intermediate clarifiers, thereby eliminating one of the
pumping stations.
114
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SITE LAYOUT . . . .
Hydraulics & Hydraulic Gradeline
IMAGINARY LINE OF NEW .
RAISED PUMP STATION -/
ORIGINAL CONCEPT
EL.765.51
PROPOSED CONCEPT
Figure 41. Raise .influent screw pumps.
115
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SITE LAYOUT
Miscellaneous
MISCELLANEOUS
Eliminate Tunnels
In the initial design, 550 ft of tunnel connected the primary tanks pipe
gallery with the digesters, secondary tanks pipe gallery, and the operations
building.
The proposed concept recommended constructing 425 ft of pipe trench with
approximately 350 ft of protected surface walkway, thus eliminating the
tunnels. The proposed plan resulted in a significant initial construction
cost savings and eliminated the tunnel drain system and sump pump. By plac-
ing the small pressure piping in a surface pi-pe breach, accessibility for
maintenance was greatly increased.
Eliminate High Mast Lighting
Five High Mast Lighting units were originally used to light the plant site.
Each mast was equipped with multiple 1,000 watt high pressure sodium lamps.
Elimination of the High Mast units was proposed, with substitution of 25'
high"roadway type luminares. 400 W mercury vapor, metal halide or 250 W high
pressure tiocllaxi lamps were proposed. Cost savings were in both initial cost
and annual electrical costs.
116
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BUILDINGS OR STRUCTURES
.Size ,
^CHAPTER 5.,,.
BUILDINGS OR STRUCTURES
SIZE
Reduce Size of Garage
The original concept provided an enclosed garage with parking bays 20 feet
wide and with 20 foot high clearance.
The proposed concept recommended reducing the bay_ width from 20 feet to 16
feet wide and the ceiling would be lowered from 16 feet to 10 feet, thus
reducing the volume of the entire building.
Reduce Garage Floor Slab Thickness
.In the original concept a garage was provided with a s lab on grade. The slab
was 8-inches thick.
In the proposed concept the slab would be reduced to 6-inches thick, which
was capable of supporting the design load of 400 to 500 psf.
Reduce Ceiling Heights in Administration Building
Tri the original concept a two story administration building was provided.
The distance from the ground floor to the second Plooc was 12 ft, 6-Inches
and from the second floor to the roof, was 11 ft, 6-inches.
In the proposed concept the overall height of the building was reduced by
two feet, one foot on each floor. This reduction was accomplishable because
the ceiling heights in the original design were greater than required for an
administrative building.
Reduce Size of Operations Building Basement
In the original concept, the operations building had a partial basement
which was used for a blower room, mechanical room, electrical room and stor-
age area. The first floor area included two offices, a conference room, and
3600 sq ft of workshop and truck space.
In the proposed concept, blower room and storage area in the basement were
reduced in size, and the first floor workshop and truck space were reduced
to 2900 sq ft.
Reduce Building Size by Moving Bulk Storage Tanks_Out side
In the original concept fiberglass storage tanks were used for bulk storage
of liquid polymer, ferric chloride, and lime. All of the bulk storage tanks
were located indoors.
117
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BUILDINGS OR STRUCTURES
Size
In the proposed concept, the chemical storage units were located outside of
the building/ in an acea accessible to trucks to facilitate truck delivery.
118
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BUILDINGS OR STRUCTURES
Location
LOCATION
l?iฎ_c-ฐntฎyฐ.r.s. -ฐy. Relocating Vacuum Filter Building
In the original'concept, both existing and new vacuum filters were used for
sludge thickening. Due to space limitations, the new vacuum filters were
located in a new building, which was not immediately adjacent to the exist-
existing and
ing building.
buildings.
Two conveyors were used to connect the
new
The proposed concept placed the two buildings adjacent to each other,
thereby eliminating the conveyor belts and using a common wall. Figure 42
' shows sketches of the original and proposed concepts.
Raise Tunnel Elevation
The original concept used tunnels which were several feet below grade.
ThA proposal recommended raising the'tunnels, making the top of the tunnel
at ground elevation. The tunnel top would serve as the sidewalks in this
proposal.
Relocate Blower Building from Top of Aeration Basins to Ground Surface
The original concept located the blower building above the aeration tanks
supported by a concrete beam and column framing system.
The proposal recommended relocating the blower building to a location adja-
cent to the aeration basins. The new location would place the building on a
concrete slab directly on the soil, thereby providing better support than
the original concept. ,
Place Boilers Inside Existing Digester Control Building
The initial design to upgrade a treatment facility included construction of
a new boiler room beside existing digesters.
The proposed concept suggested placing the new boilers
in the present
digester" control room to eliminate the construction cost of a new building.
The proposed design only required modification of the existing building and
provided an additional benefit by reducing the amount of piping required.
Relocate Blowers to Aeration Tanks
In the original design concept the blowers were housed in a portion of the
power and generation building. A. long run of 42-inch air pipe was required
between the blowers and the aeration building.
The proposed concept recommended relocating the blowers to a separate blower
building and reducing the size of the original power/generation building.
The new blower building would be located adjacent to the aeration tanks and
thus would eliminate a substantial portion of the 42-inch air piping.
119 '-.'
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BUILDINGS OR STRUCTURES
Location
VACUUM
FILTER
BLDG
CONVEYORS
SLUDGE PROCESSING
BLDG
ORIGINAL CONCEPT
VACUUM
FILTER
BLDG
SLUDGE PROCESSING
BLDG
PROPOSED CONCEPT
Figure 42. Eliminate sludge conveyors.
120
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BUILDINGS OR STRUCTURES
Location
Relocate the Blower Building and Make a Common Wall with the Aeration Basin
In the original concept the blower building was located above the aeration
tanks supported by beam and column framing, system. A superstructure with the
same type of architecture as an adjacent building enclosed the blowers.
The proposed concept would relocate the blower building between two aeration
tanks, along with the secondary sludge pump station, thereby using the tank
walls as common walls and masonry walls for a portion of the building
extending above the tanks. The proposed concept also used precast double
tees for the roof system.
Omit Gravity Thickened Sludge Holding Tank and Long Suction Lines/Add Pumps
The original concept withdrew 6-8% sludge by gravity from sludge thickeners,
and then stored the sludge in a sludge holding tank. A thickened sludge
pumping station was located adjacent to the sludge holding tank.
Due tto the length of the sludge lines between the thickeners and the holding
tanks it appeared and. that clogging would occur periodically. The proposed
concept eliminated the holding tank and placed a thickened sludge pumping
station between every two thickeners, thus eliminating the long suction
lines. Sketches of the original and proposed concepts are shown in Figure
~43~. ' ' ; '.-.-.;-- ..: ,'
121
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BUILDINGS OR STRUCTURES
Location
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122
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BUILDINGS OR STRUCTURES
Materials
MATERIALS , :
Replace Cast-in-Place Roof with Precast Concrete Slabs
The original design concept included the use of cast-in-place reinforced
concrete roof .for a building which housed several facilities, including an
open gravity thickener- tank.
The proposal recommended using a metal roof deck instead of the cast-in-
place concrete roof. .
Use Precast Floor Slabs Instead of Cast-in-Place Concrete Floors
The original design called for the use of cast-in-place reinforced concrete
floor slabs for the secondary treatment building. V:
The proposed concept recommended using . spandeck floor slabs for the
building.
Change Cover Material on Tanks ... . ;
The original concept included covered rectangular tanks for primary clarifi-
cation and aeration. The original covers were to be constructed from
fiberglass material. -:,
The proposed concept used precast, pre-stressed hollow-core concrete slabs.
Eliminate Basement Waterproofing
The original concept used waterproofing for the pump station basement in the
solids handling building, as well as a pumped underdrained system..- ;
The proposed concept eliminates the basement waterproofing because it- was
considered to be redundant with the pumped underdrained system.
Use Pre-Engineered Lightweight Metal Building
A concrete block building was used in the original design for shop facili-
ties and engine-generator combinations. f
Use of a pre-englneered lightweight metal building was proposed as a
: replacement for the concrete block building.
Use Steel Frame Stairs Instead of Cast-in-Place Concrete
Originally, the digester building stairs were designed for cast-in-place
concrete.
It was recommended that steel frame and precast concrete stairs be used in
the digester building and pump drain pit.
123
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BUILDINGS OR STRUCTURES
Floor Plans
FLOOR PLANS
Use One Single Building to House All Plant Equipment
The original plan had separate buildings to house chlorine feed equipment,
sludge handling equipment, plant heating equipment, aeration equipment, and
the administration and laboratory facilities.
It was decided that the construction of a single multipurpose building to
house the process equipment was not only cost effective, but also would
improve the functionality of the facility. Laboratory and office space also
could be incorporated into the building, if desirable.
Layout Change for Sludge Dewatering Building
A sludge dewatering building was designed with dewatering equipment on the
upper floor, and a truck loading area below. The loading area was completely
enclosed, and required a truck to back into the building for loading.
An open drive-through truck loading facility was proposed. The drive-through
capability would eliminate the need for sludge trucks to back into the load-
ing area, resulting in overall ease of operating the sludge hauling plan.
Reduce Chlorine Building Size
Original design placed for the chlorine feed and storage in the same build-
ing. Heating of the chlorine building was required about 200 days per year.
The proposed concept recommended using outdoor storage for most of the
on-site chlorine storage, reducing the building size by approximately 50%.
Savings from this revision were in the building and the monorail crane.
Eliminate Covered Vehicle Storage Area
For a plant located in a southern climate, the original design provided a
covered vehicle storage area.
Elimination of the covered the vehicle storage area was proposed.
Redesign Control Building to One Level
A two-story control building was the initial concept, with about 5,000
square feet on the second story. The second story contained a large display
area, a conference room, a restroom and several hallways, as well as other
areas.
The proposal recommended eliminating the second story, and increase the
first floor area by 2700 square feet. The proposal resulted in an overall
reduction of about 2300 square feet.
124
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BUILDINGS OR STRUCTURES
Floor Plans
. . . --%. . .If. I .
Reorganize Floor Plan and Placement of Equipment
In the original concept the solids treatment building was arranged into
three levels. In the basement were the lower access to the incinerators,
heat treatment reactors and storage space. On the first floor were offices,
electrical switch gear, laboratory, restroom facilities, lunch and confer-
ence room, vacuum filters, vacuum pumps and accessory equipment, heat
exchangers and upper access to the incinerators and heat treatment reactors.
Conveyor belts from each vacuum filter approach a main conveyor belt running
across the first floor at a 90ฐ angle to the main conveyor belt. The control
room with motor control centers and instrument panels was located on a
mezzanine level above the first floor.
In the proposed concept, all first floor facilities were compressed into a
smaller area, and multipurpose rooms were established. The vacuum filters
wererotated 90 degrees to discharge directly onto the main conveyor
: directly and accessory equipment was relocated closer to the vacuum filters.
The motor control centers were relocated to the electrical switch gear room
on the first floor, reducing the space required in the .mezzanine control
room. ...-'
Eliminate Housing for HVAC Equipment
A major interceptor pumping station had a superstructure which was 56 ft
above ground level. The top two floors of the superstructure housed heating,
ventilating, and air conditioning equipment.
The proposed concept recommended eliminating the top two floors, reducing
the overall height of the superstructure from 56 ft to 30 ft* In the propo-
sal, the HVAC equipment would be mounted on the roof of the pumping
station.
Reduce Volume of Building or Eliminate Building
In the original design, many areas of the treatment plant were covered, such
as the headwords, the grit channels, dissolved air flotation units, and the
post-chlorination/dechlorination areas. All of these areas required ventila-
tion and for most, odor scrubbing was also required. In the headworks area,
a rather substantial loft was utilized to house a traveling bridge crane.
A review of the housing needs for the various facilities revealed that
reduction or elimination of the building requirements for the grit channels,
dissolved air flotation and units and post-chlorination/dechlorination
basins was justified. Housing of the headworks was still recommended, but
elimination of the loft and the traveling bridge crane was proposed since
portable cranes could be used for the periodic removal of equipment in the
headworks area.
125
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BUILDINGS OR STRUCTURES
Floor Plans
Eliminate Housing of Exhaust Heat Recovery Muffler System
A two-story building was planned to house an engine/generator combination
and an exhaust heat recovery muffler system. The engine/generator was to be
on the ground floor, and the exhaust heat recovery muffler system on the
second floor.
Elimination of the second floor was recommended as there was no need to
house the exhaust heat recovery muffler system.
Modify Control Building to Reduce Footage
Originally the control building was designed as a two-story structure with a
total gross area of 5,000 sq ft. The ground floor covered 2,900 sq ft and
the second floor covered 2,100 sq ft.
The proposed concept suggested modifying the control building into a one-
story building and eliminating some of the duplicate spaces. By combining
the entrance and reception area, eliminating duplicate restrooms and combin-
ing the lab office with the laboratory, and reducing the building to a
single story, the space requirements were reduced to 3,600 sq ft.
Reorganize Maintenance Building
The maintenance building as originally designed was 3,600 sq ft. The
building included enclosed garages for parked vehicles and equipment.
The proposed concept recommended reducing the amount of heated space in the
maintenance building. By reducing the total square footage to 3,000 sq ft.
The vehicles would be in a covered area with open sides.
Eliminate Administration Building Basement, Move Proposed Improvement to First
Story Level
The original design constructed an administration building with a basement
of 3,700 sq ft consisting of a boiler room and shop serviced by an elevator
and two stairs.
The proposed concept recommended eliminating the basement, relocating the
boiler room to the first floor level and relocating the shop to a garage
structure.
126
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BUILDINGS OR STRUCTURES
Type of Construction
TYPE OF CONSTRUCTION
Use Gratings Over Effluent Troughs _.,''.. ,
The original concept used a reinforced concrete slab for the cover to the
raw wastewater'screw pump. '-.',-..'-
The proposed concept simplified construction by substituting grating and
handrails over the screw pump. ..-,...'''
Eliminate Walkway Enclosure
In-the original concept a 35 foot'long walkway connected two buildings. The
walkway was enclosed with masonry walls and a concrete roof.
In the proposed concept, the masonry walls and the concrete roof over the
walkway were eliminated. ,
Redesign Walls of Sludge Facility Building
The original design consisted of six anaerobic digesters connected through a
center core support building. The center core building was a multilevel con-
crete frame building with a steel frame roof system covered with 2-3/4" lift
weight concrete plank which was then covered with insulation fill concrete.
walls of the building were masonry.
The proposed recommended concept reducing the weight of the roof section by
using metal decks, rigid insulation, achieving roof pitch by tapering the ^
insulation or sloping the structural steel and using cantilevered beams
where possible. For the exterior wall, the proposed concept recommended use
of utility brick (JUMBO) and reducing the thickness of backup blocks. It was
further recommended that the parapet and limestone coping at the top of the
building be eliminated in favor of a gravel stop.
Eliminate Superstructure of Return Sludge Pump Station
A return sludge pumping installation utilized a wet well-dry well concept.
Pumps were located in the dry well, but were driven by motors which were
located in a building above the dry well.
The proposal was for elimination of the building enclosing the motors. An
equipment hatch was used for access through the slab and into the dry well.
Delete Tile Floors and Tile Walls of Main Pumping Station
The original concept included quarry tile floors and ceramic tile walls in
the influent pumping station.
Use of quarry tile and ceramic tile was proposed to be deleted, with the
concrete walls and floors being left in their natural form.
127
-------
BUILDINGS OR STRUCTURES
Type of Construction
Use Pre-Englneered Building
Originally, dissolved air flotation sludge thickeners were to be housed in a
building specifically designed and constructed for that purpose.
The proposal recommended using of a pre-engineered building of approximately
the same dimensions.
Use Insulated Steel Building Instead of Concrete Block
The original design called for a blower building with wall construction
using a concrete block with a brick veneer.
The proposal recommended a steel-frame, insulated metal panel building.
Use Reinforced Concrete Pipe for Tunnels
The original design used cast-in-place reinforced concrete tunnels.
The proposed design is to construct the tunnels from precast reinforced con-
crete pipe. Figure 44 shows sketches of original and proposed concepts.
Use Pressure Relief Valves to Prevent Uplift in Chlorine Contact Tanks
The original concept used piles to resist uplift in a chlorine contact
chamber.
The proposed concept utilizes pressure relief valves to relieve the uplift
pressures in lieu of hold down piles.
Revised Structural Framing
The original concept was a building constructed of structural steel, beam
and column with exterior masonry wall of nonload bearing masonry. Columns at
the building exterior carry a ten ton crane. The roof consists of a three
inch metal decking overlayed by insulation.
The proposed concept would be walls converted to a load bearing wall. The
ten ton crane would be carried by reinforced pilasters or solid brick piers.
The roof system would be changed to a 16-inch or 32-inch double tee pre-
stressed, precast concrete overlayed by the same insulation and built-up
roofing. Flanges of 32-inch tee were increased to four inch thickness to
provide more corrosion resistance and higher compressive strength.
Insulated Steel in Place of Precast Panels for Building Walls
i
The original concept proposed for the administration building, precast con-
crete panels backed by 2-inch rigid insulation with 6-inch concrete block
between the insulation and the concrete panels.
The proposed concept would substitute metal panels for the precast concrete,
with no change in the rigid insulation or the block wall. The metal panels
128
-------
BUILDINGS OR STRUCTURES
Type of Construction
v-GROUND SURFACE
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Q,
ORIGINAL CONCEPT
PROPOSED CONCEPT
CAST IN PLACE
TUNNEL
y~GROUND SURFACE
PRECAST RCCP TUNNEL
Figure 44. Use reinforced concrete pipe for tunnels.
129
-------
BUILDINGS OR STRUCTURES
Type of Construction
would be insulated and then attached using girts to fasten to the concrete
block wall. Figure 45 shows sketches of the original and proposed concepts.
Substitute Decorative Concrete Block in Place of Precast Concrete Panels
The original concept proposed precast concrete panels backed by 2-inch rigid
insulation with 6-inch concrete block on the interior wall.
The proposed concept would utilize concrete block with a 6-inch deep ribbed
pattern and a special color in place of the precast concrete panels. The
exterior block would use reinforcing in the cavities of the block. The
2-inch rigid insulation would be deleted, but the original 6-inch block
would be retained.
Substitute Acoustic Metal Panel for "Sound Blox"
The original concept proposed to construct the blower building utilizing
"sound blox" for the walls in order to reduce the transfer of noise from the
blowers to the outside area.
The proposed concept eliminated the "sound blox" in area of the building
where acoustical metal panels were used on the outside of the building.
Figure 46 shows sketches of the original and proposed concepts.
Use Fiberglass Covers Over Tertiary Filters
The tertiary filters in the original concept had a superstructure over the
entire filter area.
In the proposed concept, the superstructure would be eliminated and sub-
stituted with a movable fiberglass arch cover sized to fit over any one of
the filters. The cover would allow work to be done on a filter when it is
out of service. The cover would be a fiberglass arch mounted on rollers
which would roll on an aluminum track from one filter to another. Figure 47
shows a sketch of the proposed concept.
Substitute Aluminum Geodesic Dome for Concrete Dome
The original concept proposed using precast concrete domes to cover the pri-
mary sludge thickeners, gravity thickeners, and sludge decant tanks.
The proposed concept would substitute aluminum frame geodesic domes with
aluminum panels for the precast concrete domes. Aluminum domes are light-
weight and can be erected as a unit in three to five weeks. Perimeter ten-
sion is not transferred to the concrete tank. Openings for skylights, air
intakes, or exhaust can be easily inserted as required.
130
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BUILDINGS OR STRUCTURES
Type of Construction
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131
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BUILDINGS OR STRUCTURES
Type of Construction
ACOUSTICAL
METAL PANEL
METAL PANEL
ORIGINAL CONCEPT
PROPOSED CONCEPT
Figure 46. Substitute acoustic metal panel for "Sound Blox".
132
-------
BUILDINGS OR STRUCTURES
Type of Construction
/- ROOF STRUCTURE
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ORIGINAL CONCEPT
FIBERGLASS ARCHES
PROPOSED CONCEPT
Figure 47. Use fiberglass covers over tertiary filters.
133
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BUILDINGS OR STRUCTURES
Type of Construction
Use a Ladder and Safety Cage for Access to Roughing Towers in Place of
Cantilevered Walkway
In the original concept roughing towers had a cantilevered walkway
completely around the 90 ft diameter towers. This concept required
structural support for the concrete walkway and aluminum handrail, as well
as an aluminum access stairway and handrail.
In the proposed concept the walkway around the towers was eliminated, and
access to the top of the tower would be provided by a ladder and safety
cable.
Use Precast Tilt-Up Structure in Place of Cast-In-Place Concrete Structure
The original concept proposed a 3-story cast-in-place concrete structure for
the main control building.
In the proposed concept, the building would be single story slab on-grade
building. The walls would be precast concrete (tilt-up type) and the roof
would also be a precast concrete element. Additionally, equipment founda-
tions would be cast independent of the rest of the building.
Change Sidewall Construction on Oxidation Towers
Oxidation towers using plastic matrix media were to be used for carbonaceous
BOD removal prior to an aeration basin. Precast concrete walls were to be
used for sidewall construction of the towers.
The proposed concept recommended using fiberglass walls instead of the con-
crete walls.
Eliminate Parapet
A 3 ft high parapet was used around a building to visually shield HVAC
equipment located on the building roof and to act as a guardrail for mainte-
nance personnel working on the roof.
Removal of the parapet was recommended, and use of portable guardrails was
recommended when roof mounted equipment was serviced.
Reduce Windows in Digester Control Building and Dechlorination Building
The original window arrangement required heavy wall reinforcement in order
to transfer seismic loads from the roof to the wall below the windows. The
windows in the dechlorination building were located such that little light
was admitted and building appearance was only slightly enhanced.
The proposed concept recommended eliminating or reducing the number of
windows in the digester control and dechlorination buildings, and using sky-
lights to improve natural light.
134
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BUILDINGS OR STRUCTURES
Type of Construction
Build Sunscreen Over Chlorine Cylinders Instead of Enclosing
In the original design, the chlorine cylinders were to be stored. in a
completely enclosed structure. . .
It was recommended that only a sunscreen roof with open side walls be used
instead of a totally enclosed structure. '
135
-------
BUILDINGS OR STRUCTURES
Appurtenances
APPURTENANCES
Eliminate Elevator
The original concept provided an elevator to operate between the main floor
and the pump room floor, a distance of about 17 feet. The elevator would be
used only for personnel transport.
The proposed concept was to eliminate the elevator.
Use a Reduced Capacity Crane
The original concept called for a 10 ton capacity motorized crane to move
equipment in a pump room.
After checking the weights of the pump room items, it was recommended that
the crane capacity be reduced.
Eliminate Traveling Bridge Crane in Blower Building
A building supported traveling bridge crane was used in the blower building,
providing the capability of removing any of the motors, blowers, and
engines. The crane would have a capacity of 7.5 tons, which would be
sufficient to remove an engine completely.
The proposal eliminating the traveling bridge crane, and using a mobile
crane with a 5 ton capacity. This concept would require that an engine be
disassembled if it had to be removed from the blower building.
Eliminate Covered Parking From the Maintenance Building
The original design used a precast core slab roof over the maintenance
building's parking and parts storage areas.
*
The proposed concept recommended eliminating the roof over the parking area
and over the open parts storage area.
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ELECTRICAL, HVAC AND CONTROLS
Power Distribution
''CHAPTER 6 *"
ELECTRICAL, HVAC AND CONTROLS
POWER DISTRIBUTION
Substitute PVC Conduit for Rigid Steel Conduit
The original design included rigid galvanized steel conduit encased in a
concrete envelope to distribute electricity to the various points of use
throughout the plant* " ,
It was recommended to substitute PVC conduit for the rigid steel type in the
duct banks provided for the electrical distribution system. The PVC conduit
would be of the type designed to be encased in concrete. Although the PVC
does not have the resistance to crushing that galvanized conduit has, the
concrete encasement would give the necessary physical protection to prevent
damage.
Use Lower kV Insulated Cable:
In the original concept 15 kV insulated cable was used for 4800 volt power
feeders. ,
In the proposed concept, 8 kV insulated cable would be used for 4800 volt
power feeders. ,
Reduce Number of Transformers at One Location
In one building, four separate transformers were used, each connected to the
same 4160 volt system.
Consolidation into two transformers was proposed, along with conversion of
the substation to a double-ended substation (connected to two separate 4160
volt systems). The change would decrease initial capital costs slightly,
eliminate "common-mode failure", and . provide increased operational
flexibility.
Use Oil Filled Pad .Mounted Transformers
The original system used 480 volt distribution transformers, 4160 volt-
480Y/277 volt, 500 kVA, 3 phase 60 hertz dry indoor type* The efficiency for
the dry type transformers is 97%. - -
The proposed concept recommended using oil filled, outdoor, transformers
have an efficiency of 99% which results in operating cost savings as well as
initial cost savings.
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ELECTRICAL, HVAC AND CONTROLS
Power Distribution
Cable Trays for Routing 15 KV Cable
Conventional rigid galvanized conduit was used for 15 kV cable, although
cable trays were used for 480 volt power cable and 120 volt control cable,
in the original design.
The proposed concept recommended using PVC jacketed, corrugated metallic
sheathed cable for cable tray installation.
Substitute 480 Volt In-plant Electrical Distribution System for 4160V System
The original design utilized a 4160v "in-plant" distribution system. There
was an incoming service switch gear lineup and 3 double-ended load center
unit substations arranged for both primary and secondary selective service.
These substations were to be double-ended units with the transformers having
a dual primary rating of 4160V and 13.2 kV. New feeders in new underground
ducts were proposed on the assumption that existing spare ducts were in a
distressed condition. A second primary voltage of 13.2 kV was provided for
future use.
A review of the total plant load after the proposed treatment plant addition
revealed that the load would be too small for a 4160V system. The proposal
recommended a 480 volt secondary selective distribution system using exist-
ing spare ducts to maximum capability on the assumption that they are in
usable condition. A standby diesel generator was relocated closer to the
4160V entrance to the plant, to reduce required distribution facilities.
Replace Circuit Breakers with Fused Interrupter Switches
Originally, 15 kV power air circuit breakers were used for primary power
distribution switchgear.
Fused interrupter switches were proposed as a substitute.
Modify Primary and Secondary Distribution Concepts
In the original design, primary electrical distribution was a dual-radial
system with intermediate pad-mounted switching units. Secondary distribution
was from outdoor power panels, with automatic switching through dual auto-
matic transfer switches on the transformer secondarys.
The proposed concept recommended using a dual-loop system with sectionalized
switch and fused primary selector switch. Primary feed would be to double-
ended substations with secondary distribution at 480 V, 3 phase, 4W. Auto-
matic tie breakers would be used on the 480 V system to provide uninterrupt-
able power.
Material Change for Electrical Conduits
Conduit used for branch circuits and feeder circuits was galvanized rigid
steel conduit in the original design.
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ELECTRICAL, HVAC AND CONTROLS
Power Distribution
The proposed concept recommended replacing the galvanized rigid steel con-
duit with Intermediate Metallic Conduit (IMC), which is accepted by the
National Electric Code. , . '.'....-' ;
Use Load Interrupter Switches With Current Limiting Fuses
The original concept proposes to use 4.16 kV air circuit breakers.
The proposed concept uses 4.16 kV load interrupter switches with current
limiting fuses.
Reduce Size of Feeder Cables MCC's
The original concept used parallel 500 MCM feeders for 'two 'motor control'
. .- centers. These feeders had an ampacity of 760 A. The 'transformer would be
rated at 300 VA with a full load current of 360 A. .
The proposed concept would reduce the feeders to the motor control centers
to parallel 250 MCM feeders, with an ampacity of 510 A. The voltage drop for
this proposal would not exceed 1% of the rated system voltage.
Use Full Voltage Across the Line Starters .......... . ,,,,.,.,,
The original concept used 7200 volt, reduced .voltage, primary reactor type
starters for 2500 hp blower motors. .
The proposed concept would use less complicated 7200 volt full voltage,
across the line starters. The utility company permits starting of 2500 hp'
motors across the line.. '; ' "-
General Power Distribution System Modification
The original concept provided two 15 kV breakers, four new load centers, one
new 5 kV switch lineup,^and the one line diagram shows 4.8 kV r.adial feed to
each, load center, and one 4.8 kV feeder to each pair of blowers. '
In the proposed concept, two 15 kV breakers and one 750 kV.load center would
be deleted. The proposed one line diagram calls for a 4.8 kV radial feed to
a group of two load centers and a 4.5 kV feeder to. each blower and then ties
a 480 volt secondary off-load center. The proposed power distribution system
.retains the same reliability as the original system. ,
Change in Conduit Material for Underground Distribution System
The original concept used a four-wire arrangement for distribution of 4160
voltage . The underground system was steel conduit in concrete, with a mini-
mum conduit size of 3/4-inch
The proposed concept recommended using a delta three-wire arrangement,
rather than the four-wire arrangement, and reducing the minimum conduit size
from 3/4-inch to 1/2-inch. . -
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ELECTRICAL, HVAC AND CONTROLS
Power Distribution
Use of fiber conduit in concrete was also recommended in-lieu of the
proposed steel conduit in concrete.
Use Intermediate Metallic Conduit in Place of Steel Conduit
In the proposed concept rigid steel conduit was utilized throughout the
plant for the electrical wiring.
In the proposed concept intermediate metallic conduit would be substituted.
Use Owner Provided Transformer
In the original concept a 23,000-2400/4160V transformer was supplied and
connected by the electrical utility company.
In the proposed concept the owner would supply, install, and maintain the
transformer.
Use Intermediate Metal Conduit in Place of Rigid Galvanized Steel Conduit
The original concept specified rigid galvanized steel conduit and, 100%
redundancy for transformers throughout the project.
The proposed concept suggested using intermediate metal conduit for all
rigid galvanized steel conduit. It was also suggested eliminating the 100%
redundancy in the transformers.
Add Dual Primary Feed for Air Compressors
A pure oxygen activated sludge plant was planned to utilize two 1000 HP air
compressors, served by one motor control center and a single primary (4.16
kv) feeder.
The proposal recommended using individual motor controllers for each of the
air compressors/ and dual primary feeders for each motor controller. Overall
reliability of the oxygen generation system would increase from this propo-
sal although the initial cost would increase.
Add Power Factor Correction Capacitors to 10 HP or Greater Motors
The original concept had a low power factor as a result of using uncorrected
squirrel cage induction motors.
The proposed change would add power correction capacitors of sufficient kVAR
to all squirrel cage induction motors of 10 HP and above to provide a mini-
mum power factor to be 0.95. Capacitors would be connected at the motors and
not in a single capacitor bank.
Reduce Standby Power Capacity
The original design contained provisions for a 600 kw standby generator to
operate during power failures.
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ELECTRICAL, HVAC AND CONTROLS
Power Distribution
Receiving stream quality required an EPA' 'Reliability .Class II Plant which
requires generation capacity sufficient to provide treatment equivalent to
sedimentation and disinfection. Several of the unit processes at the plant
would not have to operate a power failure, which reduced the amount of
standby power required from 600 kw to 200 kw.
Revise Specifications for 480v Motor Starters
The original concept specified motor starters having circuit protectors with
current limiters rated at 100,000 amps interrupting capacity.
The proposed concept would delete the requirement for motor circuit pro-
teeters with current limiters on all 480 volt motor starters and use
standard bus bracing with combination circuit breaker starters,, rated at
22,000 amps rms. The lower amp rating was determined thorugh a closer analy-
sis of the maximum fault current.
Use Aluminum Conductors Instead of Copper
Copper conductors were originally specified for the MCC power feeder
service.
The proposed concept recommended using 750 (MCM) aluminum conductors in
place of the 500 MCM copper, conductors, since aluminum to copper termina-
tions could be specially designed to overcome the cold flow phenomenon in
thermal expansion problems associated with aluminum. Also, the aluminum
could be oversized to accomplish nearly equivalent current carrying capacity
and nearly equivalent voltage drop limitations.
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ELECTRICAL, HVAC AND CONTROLS
Instrumentation
INSTRUMENTATION
Delete Indicating Lights
In the original concept the instrument main! control panel had local/remote
indicating lights provided for the motors with local/remote switches.
The proposed concept deletes the local/remote lights.
Eliminate Standby Computer
The plant was designed for computer control of major process functions. In
case of failure of the computer, a standby computer was included in the
original design.
Elimination of the second computer was proposed, with operation of the plant
to be performed manually in the event of a computer malfunction.
Use Magnetic Flow Meters in Lieu of Parshall Flume
Under the original concept the plant effluent was metered using an existing
Parshall flume, after the flow has passed through on existing chlorine con-
tact chamber.
In the proposed concept a magnetic flow meter would be installed in the dis-
charge of the raw wastewater pumps to meter the influent flow. A bypass
would be constructed around the existing chlorine contact tanks and the
existing Parshall flume. This proposal would provide a savings in headless
and reduce the head on the primary effluent pumps.
Eliminate Digester Gas Sampling System and Use a Laboratory Type Analysis
The original design for the anaerobic digesters included a methane sampling
and analyzing system to measure digester gas methane content.
The proposed concept suggested eliminating the sampling system and using
laboratory type analysis performed once every four or five hours to provide
information on the quality and methane content of the digester gas since the
original methane sampling system was not reliable due to the high moisture
content of the digester methane off-gas. A gas analysis apparatus was
already specified in the laboratory equipment and real time analysis of the
methane content was not necessary for process control.
Eliminate One Chlorine Residual Analyzer and Two Sulfur Dioxide Mixers
In the original design, two separate analyzers were used for sulfur dioxide
feed control and final effluent monitoring. The dechlorination system also
included two mechanical sulfur dioxide mixers.
It was recommended that one chlorine residual analyzer be eliminated by
alternating the function of the single analyzer between sulfur dioxide feed
142
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ELECTRICAL, HVAC.AND CONTROLS
Instrumentation
. .
control and. final effluent monitorjrig. The turbulence at the final effluen^.
weir was used for sulfur dioxide mixing and eliminated the need for a
mechanical mixer- ... :
Replace Magnetic Flow Meters with Sonic Flow Meters
The original design included the use of 22 magnetic flow metering devices
for all necessary process streams. .--'
It was recommended that sonic flow meters be used in place of the magnetic
flow meters.
Use Microprocessor Digital Controls at Local Control Panels
The original design used conventional analog controllers in the local con-
trol panels. Analog signals were transmitted to the computer and central
control panel for monitoring only, with no operator remote control for
processes.
The proposed concept recommended using microprocessor based digital con-
trollers in the local panels in place - of the electronic analog controllers.
Data would be transmitted to the. control building in digitized form via
coaxial cables. The proposed digital data transmission system is less sus-
ceptible to noise and is more reliable.
Reduce Size of Central Control Panel
The initial design included a central control panel 30 feet in length used
to display process variables and plant status using a graphic display,
lights, and electronic indicators.
The proposed concept recommended reducing the size of the panel to 5 feet
and using it to, indicate critical variable and annunciate critical alarms in
case the computer system is down. Cathode Ray Tube displays would be relied
upon for graphic illustration of plant flow and other noncritical data.
Use, Portable Sludge Blanket Level Detector in Place of Continuous Monitoring
In the original concept, continuous monitoring of the sludge blanket level
in primary basins was used as an input to the primary sludge pump controls.
In the proposed concept, the sludge blanket level control mode was elimi-
nated and a portable sludge level detector was provided.
Delete Rate Controllers in Final Tank Drain Lines
In the original concept rate controllers were provided for the waste sludge
lines from each final settling tank. These instruments controlled the rate
of tank underflow from the final tanks to return sludge conduit. No pro-
vision was made for monitoring or controlling the rate of sludge wasted to
sludge thickeners.
143
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ELECTRICAL, HVAC AND CONTROLS
Instrumentation
The proposed concept deleted the rate controllers on the final tank drain
lines. Sludge underflow control would be by periodically opening and closing
manual shutoff valves.
Eliminate "On-Off" Blower Operation for Dissolved Oxygen Control
The original concept controlled the dissolved oxygen (DO) in the aeration
basin by turning the blowers on and off as required. Also, the control
scheme included a timer to override the DO system.
The proposed control scheme recommended that the DO be adjusted by
throttling the air suction lines to centrifugal blowers. The blowers would
then run continuously and avoid excessive wear and tear on equipment. The
two control schemes are shown in Figure 48.
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ELECTRICAL, HVAC & CONTROLS
Instrumentation
N
O-1
BLOWER
ORIGINAL CONCEPT
FLOW SIGNAL; EQUALIZATION BASIN EFFLUENT
A
PROPOSED CONCEPT
AERATION
BASIN NO,1
Figure 48. Dissolved oxygen control- system.
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ELECTRICAL, HVAC AND CONTROLS
Control
CONTROL
Use Pneumatic Actuators Rather than Electrical Actuators
The original design called for the use of electrical actuators on 143 tele-
scoping return activated sludge valves at the secondary sedimentation
basins.
The proposed concept recommended eliminating these actuators and using
pneumatic cylinder operators with pneumatic controls.
Eliminate Analog Supervisory Control Panel and Reduce Size of Main Control Room
In the original design concept, the control room covered an approximate area
32 feet by 35 feet and included approximately 92 feet of control panel along
the walls as well as a console in the center of the room.
The proposed concept recommended using a computer based central control sta-
tion. This would eliminate the need for an analog type supervisory control
^gl. space would be provided for about 20 feet of computer equipment,
backup recorders, multiplexers, etc., and the control room would be reduced
in size to approximately 20 feet by 24 feet. Figure 49 shows sketches of
original and proposed concepts.
Eliminate Return Activated Sludge Flow Pacing Controls
Return sludge flow pacing controls were part of the original sludge handling
system.
It was recommended that the return sludge flow pacing controls be eliminated
and manual adjustment of return sludge flow rate be provided instead.
Reduce Number of Color Graphic Cathode Ray Tubes and Computer Printers
A plant which utilized a computer for process monitoring and control had two
color graphic Cathode Ray Tubes in the control room and a pjrinter in both
the control room and the plant superintendent's office.
In the control room, use of one black and white CRT and one color CRT,
instead of two color CRT's was proposed. This change would allow the color
CRT to be used for graphic data and the black and white CRT to be used for
tabular data and alarms. In the event of failure of either CRT, the remain-
ing one could be used for all purposes. Elimination of the printer in the
superintendent's office was proposed, since all reports and logs could
easily be printed in the control room and delivered to the superintendent.
Eliminate Computer Link With City Hall
A computer was planned for process monitoring and control of the treatment
facility. A data link with city hall was also included to allow administra-
tive officials to obtain process and maintenance information, as well as to
perform general data processing.
146
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ELECTRICAL, HVAC & CONTROLS
Instrumentation
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147
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ELECTRICAL, HVAC AND CONTROLS
Control
Elimination of the data link to city hall was proposed. This proposal was
based partly on cost of the data link, but more importantly, due to a
greater chance of computer failure as the usage for data processing
increased. If such a failure occurred when the computer was being used for
data processing by city hall, it would reduce the overall reliability of the
treatment .facility. A separate small business computer was recommended for
city hall.
Delete Computer Control
A 10.5 mgd, 2 stage activated sludge plant was designed to be completely
controlled through the use of a computer and a variety of fixed monitoring
probes, such as D.O., suspended solids, pH, sludge blanket depth, and liquid
level. The plant could be operated manually in the event of a computer
failure.
Elimination of the computer and manual and/or semi-automated operation of
the plant was proposed. Portable probes would be used instead of the fixed
monitoring probes used with the computer.
Change Pump Controls
Pump controls specified in the original design were simplex, variable speed
control with solid state controller with wound rotor motors.
In order to save electrical energy, the proposed concept recommended using
an adjustable frequency drive system. The system would lend itself to future
expansion to the triplex mode of operation with minimal future cost
expenditures.
Use Different Control on Return Activated Sludge Pumps
Originally, the design included eddy current couplings for speed control of
return activated sludge pumps.
Because the return activated sludge pumps operated at low efficiencies, the
energy consumption was very high. The proposed concept recommended using a
single large (125 kVA) variable frequency parallel drive for all three
pumps. The more efficient drives would save energy and offset the high cost
of the drive system.
Replace Sluice Gates With Slide Gates
In the original concept, sluice gates were used for the aeration tank
influent.
The proposed concept recommended replacing the sluice gates with slide
gates.
148
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ELECTRICAL, HVAC AND CONTROLS
Control
Use One Sluice Gate in Place of Two lfe - ,.-.'..
Two parallel sluice gates were originally provided to control flow in the
chlorine tank influent channel and at the effluent pump station bypass.
The proposed concept recommended replacing each pair of sluice gates with a
single gate of equal total area.
Use Manually Operated Sluice Gates in Place of Motor Operated Sluice Gates
The original concept proposed motor operated sluice gates at each screw
pump. The function of each gate was to isolate an individual pump for main-
tenance and replacement.
The proposed concept recommended manual slide gates, since the gates would
not be operated frequently.
Change Specification for Gate Valves
The original concept specified gate valves for sizes 2-1/2 inches and larger
steam condensate and natural gas piping.
The proposed concept recommended using butterfly valves for gate valves
greater than 2-1/2 inches.
Use a Single Weir in Place of a Double Weir
The original design for primary settling tanks includes an inboard, double
weir, cast-in-place concrete effluent trough. ~~
The proposed recommendation was .to utilize an outboard, single weir,
cast-in-place concrete trough.
Use Fiberglass Trough in Place of Concrete
The original concept for the circular primary clarifier provided an
inboard, double weir, cast-in-place concrete effluent trough.
The alternate recommended was to use a fiberglass trough in lieu of the
concrete. -
Reduce Length of Splitter Weir
The original design concept included 8 ft long splitter weirs in a flow
splitting structure.
In order to reduce the potential for settling of solids and to provide
better low flow accuracy, the proposed concept suggested reducing the length
of the weirs to 4 ft.
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ELECTRICAL, HVAC AND CONTROLS
Lighting
LIGHTING
Reduce Lighting Levels by 50% '.'.
The original concept utilized a combination of fluorescent, mercury vapor,
and Incandescent lighting.
The proposed concept recommended that the lighting level be reduced to the
levels which approach the General Services Administration Energy Conserva-
tion Design Guideline. The reduction was to be accomplished by approximately
a 50% reduction in foot candle levels, use of high pressure sodium or multi-
vapor for high bay lighting, using less expensive fixtures or changing the
types of fixtures, and by using a series lighting system for site lighting
at 2400 volts.
Delete Lighting on Perimeter Road
Originally, the plant perimeter road was lit with sodium lights on 25'
poles.
The proposal was to delete these fixtures on the plant perimeter road, and
to only light the entrance road and the parking area.
General Use of High Pressure Sodium Lights
In the original concept, mercury vapor lights are used in high ceiling
areas.
In the proposed concept, high pressure sodium lights would be used in the
high ceiling areas. The high lumen output of high pressure sodium lights
would require fewer fixtures and lower wattage for the same footcandle level
lighting.
150
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ELECTRICAL, HVAC AND CONTROLS
HVAC
HVAC '. _ 7
Use an Amplified Heat Pump In Place of Electrical Resistance Heating for the , ,,.,.
Building ... .. - , .
The original concept uses electrical resistance heating to,heat buildings.
>. In the,;piropo.sed concept an amplified heat pump with the final effluent as a
... ;heatr source was substituted. The amplified heat pump could . be- used as the
main., source, fpr.heaMng the-buildings since it can concentrate the heat from
the., final plant effluent, ,to a temperature of about 160ฐF. '-,,-_-..
.Delete Pneumatic Steam Control Valves ''.'.."'""
The original concept uses pneumatic steam control valves for 'the main zone
steam lines. . '. ........
The iproposed concept would eliminate the pneumatic main zone steam control
valve and manually close the isolating valves provided to shut down the
steam main.
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ENERGY
On-Site Generation
CHAPTER 7
ENERGY
ON-SITE GENERATION
Reduce Number of Standby Generators
A plant had a total connected load of 1500 kw, with 900 kw considered essen-
tial and 600 kw nonessential. Standby generations totaling 2250 kw (3 ,@
750 kw) were planned to be installed. One of these standby generators
served as a standby to the other two generators.
The proposed concept recommended, installing emergency generation capacity
for the essential load only. Two 900 kw generators were proposed.
Use Electric Cogeneration in Place of Flaring Excess Digester Gas
In the original concept the digester gas was utilized for gas engines and
prime mover equipment. Any gas in excess of these requirements was flared as
waste.
The proposed concept recommended using excess gas 'to generate electrical
energy, with sale of this electrical energy to the power company supplying
the plant.
Produce Mechanical Energy With Excess Digester Gas
Digester gas was planned to be used for digester heating, with excess gas
used in an engine/generator combination to produce electrical energy for
on-site usage. Cooling water from the natural gas engine would also be
available for digester heating.
The proposed concept recommended using the excess gas in an engine which
would directly drive other equipment, rather than driving a generator.
153
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ENERGY
Heat Recovery
HEAT RECOVERY
Use Digester Gas for Space Heating Boilers
The original concept used purchased natural gas to fire space heating
boilers, while the excess digester gas was flared.
In the proposed concept excess digester gas would be used to fire the space
heating boilers, with minimum purchases of natural gas.
Eliminate Engine Generators
In the initial design, two engine generators were used to convert digester
gas to electricity. The generators were housed in an energy .recovery build-
ing which' had space for an additional future generator. Plant space heating
was accomplished using natural gas.
The proposal recommended eliminating the engine generators and using the gas
from the digester for space and process heating. This change reduced the
size of the energy recovery building significantly, and provided more
efficient use of digester gas since conversion to heat is much more
efficient than conversion to electricity. The proposal eliminated the need
for purchased natural gas.
Eliminate Heat Exchangers and Add Radiators
In the original design, ebullient cooling of the generator engines produced
hot water which was pumped to five new heat exchangers to heat the
digesters.
The proposed concept recommended eliminating the heat exchangers and using
radiators on the generator.
The recommended change added two new boilers to produce steam for heating
digesters. By installing radiators, it was possible to eliminate the top
floor of the maintenance building.
Install Heat Exchanger on Effluent Sludge Line
The original concept used anaerobic digestion for a combined stream of pri-
mary sludge and waste activated sludge. Digester heating was to be accom-
plished by an existing one million Btu unit and new units which are equiva-
lent to one million Btu. The new units were staged with a low temperature
exchanger preceeding the high temperature unit.
In the proposed concept a second low-temperature exchanger was added for
preheating sludge. This heat exchanger was actually only a modification of
the digester influent and effluent piping, in which the digester discharge
would be passed through a 4" pipe located concentrically inside a pipe
carrying the digester influent as shown in Figure 50. The procedure would
allow recovery of 50% of the heat in the digester discharge.
i
154
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ENERGY
Heat Recovery
BOILER
SLUDGE
RECYCLE LINE-
INFLUENT SLUDGE
HEAT INPUT
SINGLE STAGE
ANAEROBIC .
DIGESTERS
DIGESTED SLUDGE
ORIGINAL CONCEPT
BOILER
SLUDGE
RECYCLE LINE-
INFLUENT
SLUDGE
LOW TEMPERATURE
HEAT EXCHANGER
AUXILIARY HEAT
INPUT
SINGLE STAGE
ANAEROBIC
DIGESTERS
^DIGESTED SLUDGE
PROPOSED CONCEPT
Figure 50. Install heat exchanger on effluent sludge line.
155
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ENERGY
Conse rvation
CONSERVATION
Rotate Administration Building 90ฐ
The original design showed the administration/lab building with the long
axis in a north/south direction. This caused the majority of the walls and
windows to have an east/west exposure, resulting in significant energy cost
to cool the building during warm weather.
The proposed concept recommended rotating the building so that the majority
of the windows face north and south in order to decrease summertime cooling
costs.
Use Reflective Insulating Glass in the Administration Building
The glass in the adminstration building covered is about 15% of the total
area on 2 sides of the building. The original design concept used regular
plate glass for these windows.
The proposal suggested using reflective insulating glass in place of regular
glass. The proposal resulted in an increased initial cost, but reduced
cooling and heating requirements over the life of the building.
Extended Pump Discharge Pipe Below Water Surface
The original design included an intermediate pumping station to lift primary
effluent to the aeration basins. The pumping station consisted of vertical
turbine~pumps discharging into the top of a channel.
The proposed design extended the discharge pipe from each pump below the
water level in the channel. The effective pumping head was thereby reduced
through a siphoning effect. Figure 51 shows the original and proposed
designs.
156
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ENERGY
Conservation
FROM TOWERS
PLANKS
{SUBMERGED WEIR)
b
SLUICE GATES
FROM PRIMARIES
PLAN
<ฃ. PUMPS .
& MOTORS
PLATFORM
TO AERATION
1
3A
a
o
ANTI-SIPHON VACUUM
RELIEF VALVE
MAX
EL 239.0
AVERAGE
EL 233
ORIGINAL CONCEPT
PROPOSED CONCEPT
Figure 51. Extended pump discharge pipe below water surface.
157
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AESTHETICS
Odor Control
CHAPTER 8
AESTHETICS'
ODOR CONTROL
Reverse Air Flow Through Trickling Filters
Since odor-control at the treatment facility was an important consideration,
domed covers over trickling filters were included in the original concept.
Scrubbers were planned to remove and deodorize air which collected under the
dome covering.
Reversal of "normal" air flow through the trickling filters was proposed in
conjunction with elimination of the domes over the trickling filters. The
scrubbers used in the original concept would be connected through air ducts
'. to the under/flume area of- the trickling filter, pulling air downward
through the trickling filter and then deodorizing it. A localized deodorant
system was proposed for masking minor odors.
Revise Odor Control System
The original concept used ozone for odor control of air from the headwords
building, where odor emanated from both the raw wastewater and septage
delivered to the plant. Since heating requirements for the headworks build-
ing were 34,000 CFM, the ozone deodorization system was sized for 34,0_0_0_
- CFM.
In the proposed concept, the headworks was divided into separate areas for
the septage and sewage to allow individual control of odor from each source.
This change was made because over half the odor was attributed to the
septage. In the proposal, activated carbon was used to treat the more .con-
centrated odor from the headworks area, with the system .sized for J100 CFM,
and only intermittent operation required. The ozone system for the headworks,
area was in turn reduced to 17,000 CFM, as was the heating system.
Hydrogen Peroxide Injection Into Wastewater Flow
Odor control was a key concern at an existing plant, and extensive measures
were included in the original design for its control. The key odor control
measures consisted of covering the major process units and using odor con-
trol scrubbers for the air contents.
Injection' of^-nydr6
-------
AESTHETICS
Odor Control
In the proposed concept, in the low odor potential area, carbon scrubbers
were used instead of wet chemical scrubbers.
Eliminate Covers on Standby Aerobic Digesters
In the original concept, standby aerobic digesters, preaeration tanks, and
aerated grit tanks all had covers made from aluminum panels. Air was to be
withdrawn from under the covers and scrubbed for odor control.
In the proposed concept, no covers would be used on the standby aerobic
digesters, but the covers were retained on the preaeration and aerated grit
tanks.
Use Scrubbers Ahead of Carbon in High Odor Areas
In the original concept, activated carbon was used to scrub air as an odor
control measure.
In the proposed concept, in the high odor potential areas, the air would be
pretreated using a, chemical scrubber ahead of the ca.rbqn, thus reducing the
amount of activated carbon regeneration required.
Recycle Air Thru Aerated Channels forOdor Control
In the original concept, odor control was accomplished by hydrogen peroxide
addition to the plant influent, chemical scrubbing of air from under the
primary clarifier covers, and aeration of the channel between the primary
clarifiers and the aeration basins. Bight separate chemical scrubbers were
used for air from under the aeration basin covers.
The proposed concept recommended using the air collected at the primary
clarifiers as suction air for supply to the channel blowers.
Eliminate Biological Odor Reduction Tower and Use Two-Stage Carbon
The original design included a two-stage odor removal scheme employed at two
locations: 1) the headworks building for treating odors from primary and
headwork facilities, and 2) energy solids building for treating solids
handling odors. The scheme included a biological odor removal tower followed
by activated carbon adsorption with an inner stage blower for driving air
flow. The biological odor control tower operated by blowing foul air into
the bottom of the tower, and spraying secondary effluent on the top surface
of the tower.
The proposed concept recommended utilizing the two-stage odor removal scheme
in the same locations, but eliminating the biological stage. The recommended
design therefore employed a two-stage activated carbon system (considered to
be more effective and reliable) and required the blower capacity to be
increased proportional to the increased system pressure drop. Figure 52
shows sketches of the original and proposed concepts.
160
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AESTHETICS
Odor Control
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AESTHETICS
Odor Control
Delete Odor Control from Waste Activated Sludge Thickener
The original odor control system included a counter flow packed tower uti-
lizing sodium hypochlorite as the oxident. Two gravity thickeners were
arranged such that either thickener could be used as the waste activated
sludge thickener and the other used as the primary sludge thickener.
The proposed concept recommended deleting the odor control system from the
WAS thickener, since offensive odors are generally not emitted when gravity
thickening WAS. To implement the proposed change, it would be necessary to
install the odor control system on one thickener, and using that thickener
for primary sludge.
162
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AESTHETICS
Noise Control
NOISE CONTROL - ..-.-.." .
Use Sound Absorbing Enclosures to Trap Sound at the Source
In the\original concept the blower building is clad with sound absorbing
materials/ i.e. "sound blox", hung 'ceiling, and perforated metal panels to
reduce the noise level due to blowers and motors.
In the proposed concept, blowers and motors would be partially enclosed in
sound absorbing enclosures which trap sound at the source," and eliminates
the need for other acoustical treatment.
163
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AESTHETICS
Architectural
ARCHITECTURAL
Eliminate Brick Cover on Columns in Headworks
The original concept provided a headworks building with 26 interior columns.
The columns are encased in concrete and faced with brick.
In the proposed concept the brick facing was eliminated on all 26 columns.
Delete Brick Paver on Ramp to Administration Building
The original concept for the administration building indicated a brick
paver on the ramp for the entrance to the building as well as the stairway
and other outside entrance areas.
The proposed concept would eliminate the pavers from the entrance ramp, out-
side areas of the building, and on the entrance wall. Brick on the ramp
would be hazardous to handicapped people.
Delete Rubbed Finish for Concrete
The original concept required all concrete surfaces built against forms
which would normally be exposed to view, to be given a rubbed finish after
patching tieholes, voids, honeycombs, and broken edges.
The proposed concept would eliminate the final rubbed finish. Within the
proposed concept, the concrete would be finished as above except that the
final rubbing would be deleted. This would be a "smooth form finish" per ACI
301, "Suggested Specifications for Structural Concrete Buildings."
Delete Painting
The original concept painted most of the concrete floors, walls, ceilings
and stairs.
The proposed concept recommended eliminating all painting of interior and
submerged concrete.
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Use Surface Treatment of Concrete Block in Place of Stone Facing
The original concept used stone facing on concrete block.
The proposed concept would eliminate the stone facing and surface treat the
concrete block to create a pleasing effect.
Epoxy Finish in Place of Glazed Block
The original concept used glazed block for construction of the filter
building.
The proposed concept would use standard block with an epoxy finish. The new
epoxy finishes should be equal to the glazed blocks and the building
joints would be sealed.
164
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AESTHETICS
Architectural
Use Textured Block in Place of Stone Veneer
The original concept used stone veneer over construction block.
The proposed concept recommended a textured block in place of the stone
veneer.
Delete Paint on .Floors
In the original concept, painted floors were used in the headworks, solid
buildings, filter areas, garag'e, chemical buildings and pump station.
In the proposed concept the floor surfaces would not be painted.
Use Stainless Steel Instead of Aluminum
The original concept used aluminum handrails around open process facilities.
Since the proposed treatment facility was near the ocean.
Substitution of stainless steel handrails for the aluminum handrails was
proposed. The service life was estimated to be 20 years for the stainless
steel and 10 years for the aluminum.
Use Fiberglass Handrail and Grating
The original conpept proposed aluminum handrail around the aeration tanks,
rapid mix tank, grit chamber, screen pumps, in the process building, and
around the sand filters. :~
The proposed concept substitutes fiberglass handrails in place of the alum-
inum handrail and fiberglass grating in place of aluminum grating. (Adequate
safeguards for quality control and proper pigmentation to prevent ultra-
violet radiation deterioration were to be provided.)
Use Concrete Handrails
The original design of the treatment facility included anodized metal hand-
rails outside primary clarifier basins, aeration tanks, sludge equalization
area, and chlorine contact basins.
The proposed concept recommended using a concrete wall 4-inches thick and
3-1/2 feet high in the same areas.
165
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AESTHETICS
Noise Control
NOISE CONTROL
Use Sound Absorbing Enclosures to Trap Sound at the Source
In the original concept the blower .building is clad with sound absorbing
materials, i.e. "sound blox", hung ceiling, and perforated metal panels to
reduce the noise level due to blowers and motors.
In the proposed concept, blowers and motors would be partially enclosed in
sound absorbing enclosures which trap sound at the source, and eliminates
the need for other acoustical treatment.
166
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CONSTRUCTIBILITY
Structural Details
CHAPTER 9
" ' Jt?'J* " ' - ' . -^ ' ' ' -...'-. . - -
CONSTRUCTIBILITY
STRUCTURAL DETAILS . " ~ ./'.,-
Use Wall Strut System in Place of Cantilever-Walls
In the original concept, four second-stage aeration basins were built with
common walls. The interior walls were designed battered (tapered) and the
exterior walls were designed uhbattered. All walls were built in a canti-
lever fashion with reinforced concrete. , ' ,
In the proposed concept all walls would be built unbattered with Compression
struts installed at the top of the walls for strength. The struts would be
placed at 30 foot intervals. Figure 53 shows sketches of .the original and
proposed concepts.
Eliminate Peripheral Concrete Walkway on Trickling Filters . .
In the original design, the trickling filter wall .were built with double-
tie, precast concrete members set vertically in a circle capped by a poured-
in-place concrete ring. The concrete ring would resist hoop tension from the
ends of the double-tee members, serve as a "* ft wide walkway around the
filter, compensate for unevenness in the top of the double tee members, and
provide stiffness. ,
The proposal recommended redesigning the filter .with a 26" wide concrete
stiffening ring around 3/4 of the filter circumference, and the remaining
1/4 of the circumference a 36" walkway with handrail. The proposal would
reduce costs and still provide solid footing around 1/4 of the filter
" periphery to manually rotate the distributor arms.
Revised Pile Specifications
*The original concept provided pile specifications with a driving point on
"H" piles, load test for twice the required bearing capacity, and twice the
required uplift capacity.
The proposed concept recommended revising the requirements to delete the
driving points for "H" piles which have cut off elevations" below the fill
' "' "layer,' and 'a reduction iri the 'test uplift "capa'city 'to' 1-1/2 "times ; the
.- -...design. - < -... ,-'~- , - .-.-..,..>.<
Use Common Wall for First and Second-Stage Aeration Basin
Originally, the first and: second-stage aeration basins were parallel, to
each other, but did not use common wall construction.
It was proposed to relocate the second stage adjacent to the first stage,
and eliminate one of the original walls.
167
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CONSTRUCTIBILITY
Structural Details
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CQNSTRUCTIBILITY
Structural Details
Eliminate Fillets ' ... , :. . , . ., . ,."'.. -
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Aeration tanks were designed with fillets in the bottom sides and ends of
the basins. . .
Elimination of these fillets was proposed, since they serve no useful
, function. - : ! . ::
Simplify Concrete Form Work , , , ' :. ., '
In the original, design, the activated sludge tanks consisted of concrete
walls with haunches and corbels.
The proposed concept recommended eliminating the haunches and corbels in
" order to simplifv the concrete work and reduce the initial cost.
Use Straight Walls with Minimal Fillets in Place of Complex Slanted Walls in
Aeration Basins
In the original concept the aeration tank Used slanted walls which required
complex and involved forming.
The proposed, concept would use straight walls with minimal fillets in the
bottom corners between walls and floors.
169
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CONSTRUCTIBILITY
Construction Sequencing
CONSTRUCTION SEQUENCING
Eliminate Installation of Equipment for Future Design Flows
The pretreatment facilities included raw influent pumping and grit tanks.
These facilities were sized for the ultimate flow rate which was twice the
initial design flow rate. In addition, process equipment for these facili-
ties was sized to provide treatment for the ultimate flow. The process
equipment included . raw sewage influent pumps, mechanically cleaned bar
screens, and grit collectors.
In the proposed concept, any equipment not required for the initial design
rate would be eliminated.
Relocate Operations and Laboratory Building and Thus Eliminate Temporary Housing
In the original concept temporary laboratory facilities and offices were
required while the existing structure was demolished and reconstruction on
the same site.
In the proposed concept, a new location was chosen for construction of the
new facility, thereby eliminating the temporary operations laboratory and
plant control. After construction of the new facility the original structure
would be utilized for storage.
Build Primary Clarifiers Before Flow Equalization Basin
The original design required flow equalization basins during Phase I of the
project. Primary clarifiers were to be constructed five years later during
Phase II.
The proposed concept recommended constructing the primary clarifiers during
Phase I and defer the flow equalization basins to Phase II. The primary
clarifier, would be used to equalize flow between Phase I and Phase II.
170
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CONSTRUCTIBILITY
Materials
MATERIALS .... ...4' ;.:. ... .; ,. ,, . , .'.;..
Use PVC Pipe for Polymer Piping in Place of Stainless Steel
In the original concept,, the polymer transport piping was stainless steel.
In the,.proposed concept, ,Pyc pipe,.with solvent weld fittings would be sub-
-stituted for polymer piping. .
Use Steel Framing'
The original, concept used cast-in-place concrete to be used for floor and
roof construction.
The proposed concept recommended using steel framing with metal decking.
Figure 54 shows sketches of the original and proposed concepts."
'Substitute Fiberglas Grating -for Aluminum Grating ..'-.
Since the treatment facility was located in a coastal area with high, cor-
rosion rates, the original design specified aluminum gratings. ,
Fiberglass gratings were proposed;as a substitute for the aluminum grating.
The fiberglass gratings would be constructed of fire resistant, reinforced,
polyester. The fiberglass, gratings would have a 20-year life versus a
10-year life for the aluminum gratings. . , :
Use Concrete-Lined Channel in Place of.Reinforced Concrete Pressure Pipe for
Outfall Line . .. ' '".--.' ; .".. ; . '"'"' ''.'.''."'
The original concept proposed using a concrete pressure pipe for the outfall
line. '. : ....,,'.-.'.' . ...--' .-'-.. - '
The proposed concept.recommended a concrete lined channel in place of the
pressure pipe.
Use Corrugated Steel Pipe in Place of'Reinforced Concrete Pressue Pipe for
Outfall Line
The original concept proposed reinforced concrete pressure pipe for the out-
fall line.
The proposed concept recommended corrugated steel pipe as an alternative.
The pipe would be lined with a bituminous coating.
Use Fly Ash as Fill for New Construction
The original concept used sand and gravel for fill in the construction of
the plant.
The proposed concept suggested using fly ash from the incinerator ash
lagoons in place of sand and gravel. ; ..
171
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CONSTRUCTIBILITY
Materials
72"
12"
ORIGINAL CONCEPT
9"O.C6
1% COMPOSITE DECK 22 GA
4"SLAB
PROPOSED CONCEPT
(FLOOR)
Figure 54. Use steel framing.
172
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CONSTRUCTIBILITY
.Materials
"Shotcrete" Fixed Cover on Anaerobic Digester
The original concept was to construct a floating cover on the primary
digester to allow storage of digester gas.
The proposed change would construct a fixed, insulated "shotcrete" cover. A
sketch of the proposed'cover is shown in Figure 55.
Replace Concrete Flow Equalization Basins With Lined Earthen Basins
The original design included flow equalization basins constructed of formed
reinforced concrete. ~
The proposed concept suggested constructing the basins with earthern
embankments lined with gunite applied over reinforced steel. An alternative
to the first proposal was earthen embankments lined with "Hypalon".
173
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CONSTRUCTIBILITY
Materials
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60'
SECTION
ORIGINAL CONCEPT
"FLOATING COVER
INSULATION
PROPOSED CONCEPT
Figure 55. Use "Shotcrete" fixed cover on anaerobic digester.
174
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SEWERS
Manholes
CHAPTER 10
SEWERS
MANHOLES
Modify Method of Construction .-'"',
In the original design, manholes for a 54 inch interceptor were either 8 ft
diameter precast units or 9 ft diameter mansonry units with top and bottom
concrete slabs and grouted inverts. Standard 4 ft diameter precast risers
were to be used to extend from the top slab to ground level.
The proposal recommended using tee-style manholes consisting of a 12 ft
length of the 54-inch sewer pipe placed on end and supported on the 54-inch
interceptor, with an access slot'- (-18" x 48") cut in the top of the inter-
ceptor 54-inch pipe were proposed. Standard 4 ft diameter precast risers
grouted to the top of the pipe of the 54-inch pipe standing on end would
also be used. A plain concrete mat beneath the section of pipe containing
the manhole would be required for support. Alignment changes in the inter-
ceptor would be made with a pipe bend ahead or behind the 12 ft length of
pipe containing the manhole.
Replace Cast-in-Place. Manhole With Precast Manhole
In the original design, the interceptor used cast-in-place manholes.
The proposal recommended substituting, precast manhole sections for cast-in-
place manholes.
175
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SEWERS
General Construction
GENERAL CONSTRUCTION
Eliminate Alignment Holes for Control of Line and Grade
The original design required alignment/grade check holes along with pipeline
route.
The proposed concept recommended deleting the requirement for check holes.
The construction of the holes would be optimal for the contractor.
176
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INTERCEPTOR SYSTEM PUMPING STATION
Structure ' '
CHAPTER 11
INTERCEPTOR SYSTEM PUMPING STATIONS
STRUCTURE . . /';r ....'-. r .. ../V :.. .":... : ; '..-''
Change Roof Deck From Wood Truss to Precast Concrete
The original roof deck design consisted of wood trusses with a plywood roof
deck and soffitt framing. One pumping station used metal roofing and another
used asphalt shingles which would blend with the s.urrounding buildings.
Precast concrete roof decks were proposed because of their lower cost,
longer life, ability ,of: supporting a monorail hoist, and resistance to fire.
The proposed decks would* be covered with 2-inch of lightweight concrete fill
and a 5-ply tar and gravel roof.
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Change Design Method arid Use Grade 60 Reinforcing
The original design utilized the "Alternate Design Method," also known as
working stress design, and Grade 40 reinforcing.
The proposed concept recommended 'that the structure be designed for
restricted crack width, which allowed.the use of higher flexural reinforcing
stresses. Grade 60. steel would be used in the proposed change.
Reduce Structure Size due to Piping Revisions
In the original design, the pump discharged to the bottom of a common
header.
; The proposed concept recommended relocating the discharge to the side of the
common header instead of the bottom. Although there was little overall
savings in piping costs by the proposed change, the pump stations would be
several feet shorter in length and width and the overall pump station depth
would be decreased about two feet. The depth was significant because of the
prevailing high groundwater conditions.
177
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INTERCEPTOR SYSTEM PUMPING STATION
Emergency Generator
EMERGENCY GENERATOR
Reduce Size of Emergency Generator
The original design sized a standby generator for ultimate pumping station
capacity of three pumps.
The proposed concept recommended reducing the generator capacity to the two
pumps which would be required initially since the third pump would not be
required until about 40 years in the future.
17-8
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INTERCEPTOR SYSTEM PUMPING STATION
Piping
PIPING
Piping Modifications
The original design utilized a discharge gate and check valves on each pump.
On the force main leaving the pumping station, gear 'operated gate valves
were used on each side of the control valve. ": '- " - l
The proposed concept recommended using DeZurik eccentric plug valves as a
substitute for the gate valve and the check valve 'an;d knife gate valves
rather than the gear operated gate valves for isolation of the control valve
on the effluent force main.
Use Force Main Instead of Gravity Interceptor
Two gravity interceptors were tributary to the plant's influent raw waste-
water pumping station. One interceptor had a pumping station some distance
upstream.
A proposal was recommended increasing the pumping head on the upstream pump
station and converting the interceptor to a force main which would convey
flow directly to the plant headworks, bypassing the on-site raw wastewater
pumping station. The other interceptor still required an on-site raw waste-
water pumping station, but the pumping station was now considerably smaller
in capacity. Figure 56 shows a schematic of the original and proposed
systems.
179
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INTERCEPTOR SYSTEM PUMPING STATION
Piping
INTERCEPTOR
INTERCEPTOR
ORIGINAL CONCEPT
P.So
FORCE MAIN
INTERCEPTOR
TO BAR
SCREEN
PROPOSED CONCEPT
Figure 56. Use force main instead of gravity interceptor.
180
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INTERCEPTOR SYSTEM PUMPING STATION
Design Concept
DESIGN CONCEPT
Replace Electric Motors with Diesel Drive , . .
A pumping station was required during periods of heavy precipitation, to
pump flows which exceeded the treatment facility capacity into a storage
pond for subsequent treatment. The pumping station - would be utilized about
_3_% of the time. The original concept used 4 (1 as standby) pumps, each
' driven by an induction motor and each having on-off control. Diesel engine
generator sets were planned for power generation for the electric motors, as
well as for plant standby power requirements.
The proposal was to eliminate the induction motors and utilize diesel
engines to drive the pumps directly. The standby pump was eliminated, and
only 3 pumps were used in the proposed design. The diesel engine on one of
the pumps was also proposed to drive a standby generator for other plant
requirements.
181
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-------
OCEAN OUTFALL
Covering Material
."'.'.'.'. - . CHAPTER, 12
. ''- OCEAN OUTFALL ' . .
COVERING MATERIAL
Eliminate "Armor Rock" Covering
In the original design, a 36-inch ocean outfall was covered with a 5-inch
thickness of "Hevicote"and then to be further covered by 9-inch to 12-inch
rocks. Then, a several foot thick layer of "Armor Rock" was to be added for
additional weight and protection. The, top of the "Armor Rock" was to be 2_
feet deeper than the expected limit of erosion of the ocean floor.
The proposed concept' recommended elimination of the "Armor Rock" covering,
since the 5-inch Hevicote and the layer of 9-inch to 12-inch rocks would
provide sufficient protection and weight.: No change was proposed for the
depth of the^outfall below the ocean floor. "Figure 57 'shows sketches of the
original and proposed concepts.
Use Hold Down Piles in Place of Rock Cover --.".- .
in the original, a layer of rock and a layer of. "Armor Rock" would cover for
the outfall pipe.
The proposed concept recommended eliminating both layers of rock covering
and anchor the outfall to 2 pile bents at 40 ft intervals using pile caps
and hold down strips. Figure 58 shows sketches of the original and proposed
concepts.
Reduce Cover Over Outfall by 2 ft
The original design included one foot of 9-inch to 12-inch rocks over a
36-inch diameter ocean outfall, with an additional 2 to 3 foot layer of
12-inch "Armor Rocks." The top of the "Armor Rock" was planned to be 2 ft
below the expected limit of erosion of the ocean floor.
The proposed concept recommended that the outfall be raised two feet,
placing the expected limit of erosion at the surface of the layer of "Armor
Rock." '.':'... ' '.-'.--" /.,-".
183
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OCEAN OUTFALL.
Covering Material
LIMIT OF EROSION
NATIVE BACKFILL
ORIGINAL CONCEPT
LIMIT OF EROSION
NATIVE BACKFILL
PROPOSED CONCEPT
Figure 57. Eliminate "Armor Rock" covering.
184
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OCEAN OUTFALL
Covering Material
LIMIT OF EROSION
ORIGINAL CONCEPT
OCEAN FLOOR
HOLD DOWN STRAP
^Tป
PILE BENT
J^r
PROPOSED CONCEPT
Figure 58. Use hold down piles.
185
NATIVE BACKFILL
-------
OCEAN OUTFALL
Construction Material
CONSTRUCTION MATERIAL
Change From Steel to PCCP
The original outfall design used a steel pipe with epoxy phenolic coating on
the interior and coal tar epoxy plus two inches of mortar coating on the
exterior.
The proposed concept recommended constructing the pipe of PCCP, with j5
1/2-lnch nonfloat concrete covering on the outside.
Reduce Wall Thickness of Pipe
in the original design a steel pipe outfall with a wall thickness of
5/8-inch had an internal coal tar epoxy coating and a 3-inch to 5-inch
layer of "Hevicote" on the exterior.
The proposal recommended reducing the wall thickness from 5/8-inch to
1/2-inch. Interior and exterior coating on the outfall pipe would remain
unchanged.
Substitute Reinforced Concrete Pipe for Final Effluent Box Conduit
The original design used a final effluent conduit box constructed of
poured-in-place concrete.
The proposed concept recommended using precast reinforced concrete pipe.
186
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OCEAN OUTFALL
Construction Technique
CONSTRUCTION TECHNIQUE
Reduce Radiographic Inspection ^ ,;
.. The original design used welded steel pipe with full circumference radio-
, logic inspection of. the welded joints in accordancewiththeAmerican
Petroleum Institute (API) Specifications.
Because the outfall would be operating at low pressure, it was suggested
that AWWA Spec. C200 for pressure testing be used instead of radiologic
testing. However, radiologic testing was recommended on 10% of the joints
fpr verification purposes. '. '...-;.- , ' '
Join Pipe Above Water
The original design used '16 ft lengths of reinforced concrete pipe with
individual pipe lengths joined beneath the water surface.
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In order to reduce construction and - underwater time, the proposed concept
recommended joining two or more lengths of the pipe prior to placement in
the water_for final positioning.
187
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OCEAN OUTFALL
Design Concept
DESIGN CONCEPT
Eliminate Transition Structure
At the transition point between the rigid land section and the semi-rigid
ocean section of an outfall, a transition structure was provided. This
structure housed valves for insertion of the cleaning pig into the ocean
section of the outfall.
It was proposed to delete the transition structure and replace it with solid
piping and a flexible connection. The pig insertion location would be at the
treatment plant site. This location would allow cleaning of both the land
and ocean sections of the outfall.
Eliminate Diffuser .
An outfall into a large river had a 200 foot diffuser, for dispersion of the
effluent. No regulatory agency requirement, direct or indirect, was evident
for the diffuser.
The proposed concept suggested that the diffuser be eliminated.
188
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APPENDIX A
VALUE ENGINEERING PROGRAM EVALUATION
The EPA's mandatory value engineering program has been in effect since 1977,
with a voluntary program in force for the previous year (1976). Value engineering
studies completed under the mandatory program, comprising 93 individual workshop
reports, were used to evaluate the effectiveness of the program. The evaluation
encompasses subjective and objective conclusions due to the nature of the data.
Subjective evaluations present conclusions based on opinions expressed by the
EPA's Regional VE Coordinators and discussions with VE consultants. Objective
evaluations were based on the data abstracted from the 93 reports.
The VE evaluation is presented under the following general categories:
Productivity of VE Teams
ซ Potential VE Savings
Acceptance of VE Recommendations
-.- i .* Identification of High Cost Components ,
Composition of VE Teams
ซ Costs and Level of Effort for VE Studies
Reasons for Rejection of VE Recommendations
e General Observations
In addition, a comparison of the effectiveness between VE teams different
from the Design firm and VE teams selected from the Design firm was made, and is
included in the following discussions.
PRODUCTIVITY OF VE TEAMS
One measure of the VE teams' productivity is the average number of ideas
evaluated by each team member. This is the only item for which data can be
directly abstracted from the VE reports. The resulting values are shown in Table
A-1. ... .''.. . .
TABLE A-1.
IDEAS EVALUATED PER TEAM MEMBER
Value
Average,
Standard deviation
Overall
. 2.82
1.88
Ideas evaluated per team
Separate
VE firm
3.32
1.96
member
Same
VE firm
1.89
1.13
Inspection of Table A-1 shows that separate VE firms evaluate about 76
percent more ideas than VE teams from the same firm as the designer.
The significance of this fact is clouded by many issues such as:
Complexity of design project
* Competance and experience of design firm
A-1
-------
Exposure of VE team members to design from different firms
Experience of team members in participating in workshops
The complexity of the design project influences the time required to consider and
evaluate various ideas. If the design is complex, it takes longer to seek out and
identify the design alternatives.
The second issue interrelates with the presentation of the design. Firms
with greater experience generally think through the design thoroughly, by drawing
on past experiences, and thereby minimize the number of alternative designs. More
experienced firms avoid obvious design deficiencies, which are frequently
introduced by less experienced firms.
The third issue also involves experience, but this time it relates to the VE
team member. Team members who have had extensive exposure to designs by different
firms can identify alternatives quickly and competently. Exposure could be
obtained through plan reviews or by visiting operating treatment facilities and
observing the good and bad features at each location.
The final issue deals with the number of workshops completed by individual
team members. There tends to be a learning curve effect in VE workshops that
indicates improved proficiency in identifying and evaluating alternative ideas
with each successive workshop. In other words, the efficiency of individual team
members increases with the number of workshops completed.
However, these issues are more applicable to individual projects and not the
whole program. Therefore, although the constraints presented must be considered,
there is a definite trend that shows VE teams from a different firm are more pro-
ductive than VE teams from the design firm. Many subjective reasons can be
developed around this phenomenon, such as: the VE teams from different firms have
to prove their capability; or the VE team may want to show up the design firm
because of past grievances; or the VE teams from the design firm have similar
design philosophies and therefore do not recognize potential alternative ideas to
achieve equal functions; or VE teams from the design firms do not want to create
problems for their firm and peer engineers and therefore are not as thorough in
their reviewing of the project. Any one or more of these opinions could apply to
several of the VE studies, but it is improbable that these or similar reasons
would permeate the whole program. Therefore, it appears that a VE study by a firm
different from the designer is more productive.
POTENTIAL VE SAVINGS
The potential VE savings have been computed as a percentage of the construc-
tion costs to eliminate the effect of project size. These data were developed for
various points in the design schedule represented by the percent design comple-
tion stage. To identify the potential savings attainable at various points
through the design, the same ranges in percent of design completion presented in
Table A-2 were used. The results are shown in graphical form in Figure A-1.
A-2
-------
Inspection of Figure A-1 clearly shows a point of diminishing, return, in
terms of the potential savings, the closer the design is to completion. The .shape
of this curve is consistent with the classic curve published in texts on value
engineering which depict a lower potential savings with time.
The potential savings have been subdivided into those developed by VE teams
from firms other than the Designer's firm and those VE teams selected from the
design firm. The results are shown in Figure A-2. As would be expected from Table
5 on productivity, the VE teams from the Design firm identify a smaller potential
savings':than those VE teams from different firms. Probably, many of the issues
suggested for lower productivity of the VE team from the design firm are applic-
able to this situation also. The most probable reason is that the team .members
from the Design firm are entrenched, even subconciously, in the standard design
methods used by'their firm and therefore do not see alternatives that are.obvious
to others from outside the firm. They tend to be less "creative" in terms., of dif-
ferent design: approaches. ' ,--..' < .. ; ,;
Another method of identifying the effectiveness of the VE teams in develop-
ing potential savings is to compute the savings per team member. For the VE
studies that included more than one workshop, the potential savings from each of
the workshops were summed and divided by the total number of-: team .members from
all the workshops. The results of this analysis are shown in Table A-,2. The
overall 'average potential savings per team member is $353,100. Separate. VE team
members have a higher average potential savings than some VE teams. ; ,
TABLE A-2. POTENTIAL VE SAVINGS PER TEAM MEMBER
Value
Average
Standard deviation
Overall
$353,100
$292,000
Separate
VE firm
$374,200
,$310,500
"-.'- Same :
VE^firm , .
.'- ; ,$238,400
, $110,800
The potential savings are presented in terms of life cycle costs, which
includes an allowance for operation and maintenance (O&M) costs. However, as
described in more detail'in a later section, very few of the VE reports include
O&M costs, and therefore the savings presented represent principally initial cap-
ital savings. Less than 15 percent of the reports include O&M costs of any
magnitude. .
A further analysis was performed to identify the potential saving in terms
of. dollars ,($) per idea by comparing these unit values for potential savings, an
indication, of the magnitude of the individual ideas. The results of this analysis
are shown in Table A-3. The 12. percent difference in the values between the same
and separate VE teams is not considered significant when considered in conjunc-
tion with the methods of costing of the various ideas recommendation.; The "mix"
of ideasr, that is the, ratio of large 'value ideas to small value ideas' is not
known, and therefore further deduction cannot be made using this data.
' A-3
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Figure A-l. Potential VE savings.
A-4
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.A-5
-------
TABLE A-3. POTENTIAL SAVING PER IDEA
Potential Per Idea
Separate Same
Item Overall VE firm VE team
Average1$125,200$112,700$126,100
1Values in Table A-2 divided by values in Table A-1.
To obtain yet another perspective on the amount of potential savings that
could be anticipated, a dimensionless graph showing a trend line was prepared.
Using the historical data, the ratio of potential savings to construction cost
was plotted against the construction cost. This curve is shown in Figure A-3, and
clusters the data points in a more orderly fashion. The trend line was located
using professional judgment, and can be used to judge the effectiveness of the VE
study. VE studies with identified potential savings that fall on the trend line
may be represented as average, below the line is below average and above the line
above average.
To show the "shotgun" scatter of the data points, Figure A-4 was prepared.
This figure plots the data points of potential savings against construction cost.
It is interesting to note the wide range of potential savings in the $10 million
to $20 million construction range. Potential savings range from a low close to
zero up to about $4.5 million! Possible reasons for this are too numerous to
list, and can only be deduced by subjective analysis. They would probably center
around combinations of "bad" and "good" designs. For example, the high potential
savings could have been produced by a" "good" VE team and a "bad" design, with the
reverse being the case for the low potential savings point. "Good" and "bad"
could be represented generally by experience for both the VE team members and the
design firm.
ACCEPTANCE OF VE RECOMMENDATIONS
The most important aspect of the EPA's VE program and the VE studies is the
rate of acceptance of the VE ideas or recommendations. Data were abstracted , from
the individual workshop reports that contained estimates for both the potential
savings and the accepted savings. These data were converted into percentages of
their respective construction costs and then arranged under the percent of design
completion, as described in the sub-section on Potential VE Savings. This analy-
sis was completed for the dollar amounts accepted and the number of ideas/ recom-
mendations accepted. The results are presented graphically in Figure A-5. The
curves in Figure A-5 are in general agreement by showing a greater rate of accep-
tance early in the design, and then again later in the design. The lowest accep-
tance rate is found at about the mid-point of the design schedule. The average
acceptance rate for the dollar values is about 46 percent- while that for the
ideas/recommendations is about 44 percent. The evaluation of this category for
the VE teams from separate firms and those from the same firm., resulted in an
interesting reversal as was shown in Table A-4. The VE teams from the design firm
have achieved a better acceptance rate than those from separate firms. There are
several reasons that could explain this fact. These include:
A-6
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A-9
-------
TABLE A-4. ACCEPTANCE RATE OF IDEAS/RECOMMENDATIONS
Acceptance Rate, percent
Separate Same
Item Overall VE firm VE team
DOLLAR
Average 45.6 39.2 52.5
Standard Deviation 25.4 23.7 24.8
I DEAS/RECOMMENDATIONS
Average
Standard Deviation
43.9
20.1
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18.5
50.8
21.3
Frequently, the VE teams include firm principals, supervisors or more
senior personnel than those on the design team, and therefore the
design engineers may feel pressured to accept the suggested ideas.
The ideas/recommendations suggested by the VE team probably do not
include ideas that are totally foreign to the design firm. (They do not
offer a fresh point of view to the design). In other words, they fit
into the general design mold expoused by the design firm.
Peer pressure may play a role in that the design engineers and VE team
members have to work together on future projects. Greater acceptance
may relieve any possible tensions.
Eliminates the "not invented here" syndrome, and therefore the ideas
are more acceptable. This would occur principally in long standing
firms who have developed standardized methods for designing certain
items and facilities.
There would also be less skepticism about the motives of the VE team in
suggesting alternative designs.
A second analysis was completed to determine the accepted dollar saving per
team member, and the results are shown in Table A-5. This table shows a signif-
icantly higher accepted dollar savings per team member for VE teams from separate
firms than for VE teams from the design firm. This statistic would tend to indi-
cate that separate VE teams identify more ideas/recommendations with significant
savings, which obviously would create substantial design changes. These higher
values also could be reflected in the estimated operation and maintenance
savings, which extend over the life of the project and are born entirely by the
local community.
To deduce the magnitude of the ideas accepted, the ideas' accepted per team
member were computed, and in conjunction with Table A-2, the dollars per idea
were obtained, as shown in Table A-6. Inspection of this table shows that the
dollars per idea accepted for separate VE teams is about 111 percent greater than
for the VE teams from the design firm, which is a significant amount. It tends to
A-10
-------
"TABLE., Ar5... DOLLAR ACCEPTANCE PER TEAM MEMBER
Acceptance per team member, $1,OOP's
Item
Overall
:Separate
VE firm
Same
VE firm
Average
Standard deviation
129.8
99.8
145.7
103.9
82.1
71.8
TABLE A-6 . DOLLAR ACCEPTANCE PER IDEA
Item
IDEAS PER TEAM MEMBER
Average . _..
Standard deviation
Overall
0.45
.0.21 .'
Acceptance rate
Separate
- - * - - . . -. ' '
VE firm
. 0.42 :
0.20
Same
VE firm
0.50
0.22
DOLLARS PER IDEA
Average
288,400.
346,000
164,200
ideas for VE teams from the design firm than for separate VE teams. VE teams from
the design firm show a:higher acceptance of smaller ideas, which together total
to a higher value than -for,separate teams. However, this fact also, indicates that
there are fewer radical or different design.approaches, which might be considered
less creative or imaginative by some people.
Finally, to test whether the rate of acceptance was affected by, the report
presentation and; organization, each of , the workshop reports were subjectively
rated. The rating was based on the ease with which data could be abstracted,
report organization, inclusion of unnecessary extraneous material, conformance
with the EPA format, thoroughness of.data evaluation and the overall appearance.
Naturally considerable personal preferances are included in the ratirigs, but they
do tend to identify trends. The ratings were divided into three categories: below
average, average', and,above average. The major determining factor was conciseness
and clarity of the reports. The results are plotted graphically on Figure A-6 and
show a distinct improvement in the rate of acceptance with an improved report.
IDENTIFICATION OF.HIGH COSTCOMPONENTS ;
To obtain an indication of the-high cost components of wastewater treatment
facilities, the bid.tabulations'of-several treatment plants were studied, and the
costs were divided into the standard 16 division format recommended by the Con-
struction Specifications Institute (CSI). Using these costs, their percentage of
the total cost was Determined and is presented in Table A-7.
A-11
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Figure A-6. Acceptance rate based on report presentation and organization.
A-12
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Inspection of Table A-7 shows the major costs for a wastewater facility are
in concrete, equipment and mechanical divisions, each representing about 20
percent of project costs. The next tier of costs are included in the site work,
metals, special construction and electrical divisions, representing between 5 and
11 percent of the project cost. The remaining nine divisions combined make up
only 9.6 percent of the total construction costs. However, although these nine
divisions make up a small percentage of the total constructions cost,
individually, they could represent a significant savings to the project.
: ..'..' TABLE A-7. IDENTIFICATION OF COSTS
CSI division
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Percent of total construction costs
Division title Average
Concrete
Equipment
Mechanical ,
Sitework
Electrical
Metals
Special construction
General requirements
Finishes
Masonry
Wood and plastics
Thermal and moisture protection
Doors and windows
Specialties
Furnishing
Conveying systems "
21.4
21.3
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9.3
5.4
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2.6
1.5
; 1.5
0.9
0.9
0.6
0.5
0.7
0.4
Range
12.7
12.5
10.0
6.0
5.0
2.6
2.3
1.6
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0.4
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- 2.9
- 3.8
- 1.5
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- 1.7
- 1.4
The treatment facilities'used to determine the cost identification in Table
A-7 represents a ,cross-section of geographical location, type of facility and
design engineer. The facilities vary in size and complexity and therefore are
fairly representative of the treatment plants being constructed in the U.S.
COMPOSITION OF VE TEAMS
The data presented, in Table A-7 reflect the disciplines necessary for the VE
teams. Care should be exercised in selecting team members to ensure an adequate
level of experience in the engineering 'disciplines necessary for a particular
workshop. The design of wastewater treatment facilities, especially smaller
facilities, is largely coordinated and completed by sanitary engineers. Inspec-
tion of Table A-7 shows that sanitary engineers have principal control of over 70
percent of the construction cost of a project. The sanitary engineer .normally
selects and sizes all tankage and basins, specifies the equipment and completes a
majority of the mechanical work. Obviously other engineering disciplines are a
part of any design team, but, with the exception of electrical engineering, they
only affect about 20 percent of the construction cost of the project.
A-13
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These facts should be carefully considered when assembling a VE team. Also,
the timing of the workshops is another important variable to consider when
establishing a VE team. As the design nears completion, the team members selected
should have experience in design aspects.
All VE teams should include a minimum of two sanitary engineers in order
that they can inter-react and thereby gain the most benefit in the creative
phase. Early in the design phase, architectural, mechanical and structural engi-
neers are not really needed as the design is ill-defined in these disciplines.
Depending on specific circumstances, a geotechnical engineer may be desirable.
Later in the design, when working drawings are available, the other disciplines
should be included if the type of facility warrants it. An architect may be
desirable for most VE studies because of their knowledge of building materials
which is applicable' to more than the site buildings. Architects may affect as
much as 10 percent of the construction cost by accumulating the areas in which
they are directly involved.
In summary, the VE team composition should be assembled after carefully con-
sidering the following: ' '
High cost components - favor more sanitary engineers
Timing of workshop
Special construction consideration or techniques
Type of facilities to be constructed
After evaluating these factors, the VE team can be selected.
COSTS AND LEVEL OP EFFORT FOR VE STUDIES
The engineering costs of the completed VE studies were analyzed and the data
plotted in Figure A-7. The line of best fit, using a least squares analysis, was
also computed and is indicated on the drawing. Naturally there will be differ-
ences in VE costs, principally associated with expenses and the overhead rates of
the firms, but this curve represents historical fees for a project.
The level of effort required for VE studies was also evaluated from other
data abstracted from the individual workshop reports. The total number of team
members (number of workshops times number of team members in each workshop) for
each VE study was plotted against the estimated construction costs, as shown in
Figure A-8. Superimposed on this figure is an envelope of the suggested level of
effort necessary for conducting a VE study. The upper and lower limits were
established by considering the data, experience in conducting VE studies and dis-
cussions with consultants who perform VE studies. The envelope represents only a
guideline for establishing a reasonable number of team members for the study and
is based on a minimum of one workshop.
To test whether there is any correlation between the number of team members
and the potential savings, a second plot of data points was completed, as shown
in Figure A-9. Inspection of this figure shows that there does not appear to be
any advantage to have more than 11 team members, at least for the smaller
projects.
A-14
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Figure A-7. VE fees.
A-15
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A-17
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REASONS FOR REJECTION OF VE RECOMMENDATIONS
In responding to the Preliminary VE Reports, Design engineers have developed
and used an enormous variety of reasons for rejecting ideas/recommendations sug-
gested by VE teams. However, analysis of the reasons used tend to show they are
variations of a theme, and can be grouped into a relatively small number of basic
reasons. These basic reasons are presented and discussed in this section. In many
instances, if the VE team could specify locations where the process, equipment
item, type of material, etc. which is suggested in the idea/recommendation is
successfully used, many of the Designer's concerns would be alleviated.
The most important single reason that frequently underlies the
Designer's rejection of an idea, is the liability issue. The Designer
has the responsibility, and the liability, of ensuring a reliable and
fully operational treatment facility. If a Designer is obligated to
accept an idea that he does not understand, has not designed into other
projects, or does not like, he may request relief from liability on
that specific item.
A reason used frequently, and that is difficult to dispute, is the
probable "delay" that would be caused by implementing an idea. The VE
team normally includes redesign fees and makes allowances for estimated
times based on their own experiences. These may be substantially dif-
ferent from the Designer's estimates, which would have to prevail.
The most often used rejection is basically one of "opinion" on a par-
ticular item. The Designer's opinion is then pitted against the VE
team's opinion, and the client is frequently left with making the final
decision. In many cases, it represents an "easy out" for the Designer
who doesn't believe in the VE program or doesn't want to be bothered
with changing the way he has designed this item on other jobs. It
therefore harbors a generally unimaginative approach to designing
wastewater treatment facilities.
Many Designer's have used safety aspects to reject ideas. These can
extend to all areas of the design including equipment, roads and tank-
age. Using safety as a rejection reason is difficult to counteract, as
any VE team that voices an opposing opinion could be considered as
being unconcerned about the safety of plant personnel. It therefore
becomes an emotional issue.
Many ideas are rejected by the Designer on the advice of equipment sup-
pliers and vendors. This normally occurs with smaller, less experienced
firms that tend to rely on suppliers for design help.
Geotechnical information has been used to reject ideas as well. This
occurs when the geotechnical report was not made available to the VE
team for whatever reason. Typically, these are valid reasons for
rejection.
In some cases, a good idea is rejected because it is new technology and
the designer did not want to take a chance on failure. However, with
A-18
-------
the new Innovative/Alternative program introduced by the EPA recently,
these may not occur as frequently,."
A rejection that has been used occasionally is an admission by the
Designer that he did not provide adequate background material. The sug-
gested recommendation is good, but because of these other considera-
tions, of which the VE team was not aware, it cannot be implemented,
and must be rejected. The VE Team Coordinator (VETC) therefore should
ensure that all available and pertinent information is collected for
the workshop. The presence of an Owner's representative at the work-
shop is another method that can be used successfully to stem this type
of rejection. .
Another type of "rejection" is> based on previous implementation of the
idea. The Designer's response is typically, "That's a good idea which
we have already incorporated into the design. Unfortunately, the draw-
ings showing this change were not available for the VE workshop". This
rejection really is an acceptance of the idea> ' which is the intent of
the program, but a rejection of the VE7team's recommendation.
ฎ One rejection used infrequently was based on the fact that a regulatory
agency required that the original item be incorporated into the design.
In this case,* the specific item should have been listed as a con-
straint, and not allow the VE team,:to waste valuable time evaluating
alternatives for this item. -:
On several occasions an idea 'initially has been accepted by the
Designer, only to be rejected later. Later rejection is usually based
on a more detailed re-evaluation of the idea and its affect on other
facilities in the plant. Rejection could be based on cost or other fea-
tures such as incompatibility with selected equipment,etc. This type of
rejection is unavoidable, because it is based on a more careful evalua-
tion by the Designer, who 'initially had liked the idea.
The final rejection listed here is the idea of flexibility, which has
already been included- under the rejection based on opinion. In this
case the idea relates to the "required" amount of flexibility and
therefore infers a predetermined judgement. Typically, it is used in
cases such as "Fewer units don't provide the required amount of flexi-
bility". The VE team should be provided with all documentation relative
to any specific requirements of the design.
GENERAL OBSERVATIONS ' - r
Many observations were noted during the review of the 93 individual workshop
reports, and these are presented here in an effort,to improve the overall program
by identifying pitfalls and successes. Hopefully, if future design engineers and
VE team members review and think about these comments, everyone will benefit from
performing Value Ingineering studiesi Many observations are similar to those pre-
sented in the EPA manual on Case Studies (EPA-43019-77-009). The following are
the general observations.
A-19
s;.
-------
The VE program has been eminently successful when measured in terms of
estimated life cycle cost savings.
For the open minded participants in the VE process, the VE workshop has
broadened horizons on alternative design techniques. The program actu-
ally provides a good mechanism for the exchange of ideas and informa-
tion regarding wastewater treatment facilities.
Participation of an owner's representative in VE workshops has proved
beneficial to both parties. The VE team gains from the background
information provided by the representative while this person gains from
the frank 'discussions about alternative ideas, which therefore give the
owner a better understanding of the ultimate facilities.
Participation in the VE process builds a greater awareness of investi-
gating design alternatives and thinking through the proposed design
more thoroughly. Any designer who knows his project is going to be
value engineered will tend to be more thorough in the design and offi-
cially evaluate all elements of the design before they are submitted to
the VE team.
Increased frequency of participation in VE workshops sharpens skills
of the team members. This results in more efficient and productive
workshops. Participants know what to expect and are use to the formal-
ities of going through the five VE phases, and are able to recognize
high cost areas quickly. New team members tend to feel insecure and
some pressure as they don't know what to expect next.
It is apparent from reviewing the workshop reports and participating in
value engineering studies that designers frequently do not understand
the alternative. As a result, good ideas are often rejected. It is
important to ensure that ideas are well presented and explained. When-
ever possible, sketches should be used for each recommendation, along
with clear, concise and legible computations and notes showing all
assumptions.
Many preliminary VE reports contain poor backup notes relating to the
specific recommendation. The Designer therefore has difficulty in fol-
lowing the recommendation through and rejects the idea. This observa-
tion follows from the previous one.
Many recommendations presented in preliminary VE reports encompass more
than one idea. Frequently, the whole recommendation is rejected because
of a single bad idea and several good ideas are lost. VE teams should
be encouraged to include only a single idea in each recommendation and
avoid the concept approach. The latter approach could be incorporated
by combining several individual ideas to show an overall suggestion.
Each recommendation page (worksheet 10 in the VE workbook) should
include a concise description of the "before" and "after" concepts of
the idea. Including these will demonstrate to the Designer that the VE
team has grasped the intent of the original concept. Conversely, if the
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VE team is incorrect in their' interpretation of the concept, the
description presented will clearly1identify the error. This requirement
will also improve communication' with third parties reviewing the
/reports, such as regulatory agencies, personnel not directly involved
in the process (council members), and other staff members from the
Designer and VE firm's.
The concept of including only a single idea per recommendation will
result in many recommendations that are mutually exclusive. This is not
a detraction, but rather it presents an opportunity for the Designer to
select an idea from a number of good ideas. It also provides the
vehicle to present several alternative methods of accomplishing the
same function. :
Discussions with regulatory personnel, VE teams and designers indicates
there is some distrust of outside firms doing the VE. This is espe-
cially true, if the firms are from the same geographic area and compete
regularly for projects. This probably will become less significant as
-time .passes, ,and the VE process is more understood by consulting
firms.
There has been.much criticism of the VE program by consultants who feel
that their design capability and integrity are being questioned, and
that the program is not warranted. Their selection as the Design Engi-
neer by the client indicates they were the most qualified for the pro-
ject. These people fail to realize that VE is not an imposition or a
slur on their ability, but rather VE provides an opportunity to obtain
differing viewpoints from other knowledgeable engineers. There is room
for improvement on any design or project and VE provides the opportun-
ity to tap these ideas at relatively little cost.
Most of the savings identified in the VE reports were related to ini-
tial costs. The inclusion of operation and maintenance (O&M) require-
ments was singularly poor. Even though much O&M data is already avail-
able in several published and unpublished reports, there should be a
single publication containing a comprehensive O&M cost guide on waste-
water treatment facilities. .
Many reports reviewed were inconsistent in the method of completing
life cycle costs (LCC's), and .some did not even include these computa-
tions. It is imperative that LLC's be completed as accurately as
possible. This suggestion also requires additional cost data as
: mentioned in the previous observation.
Many of the reports were very badly organized and contained totally
inappropriate information. Review of the Preliminary VE Reports would
be easier and quicker if the general EPA format is followed by the VE
team. This will ensure uniformity in report content and elimination of
'. unnecessary information. As shown earlier .in this chapter, poorly
organized .and presented reports result in a lower acceptance of VE
ideas/recommendations.
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There appears to be a tendency in VE teams to strive toward the "goal"
of identifying savings in a ratio of 10 to 1 over the VE fee. Another
item is the "bean count" factor which requires that the VE team evalu-
ates at least 3, 4, 5, or more ideas per team member to show they have
done their work competently and thoroughly. Frequently, these two fac-
tors cause the VE team to lose sight of the purpose of the VE program
and in their zeal to achieve their "goal" or "bean count" include ideas
that they would not implement themselves. VE team members should be
encouraged to consider all ideas carefully and develop the alternative
as though they were going to use the idea on one of their own projects.
VE teams should also be encouraged to identify those ideas/recommenda-
tions that are not as good as the others or would not be "pushed" by
the VE team.
The VE report should include an abbreviated description of the project
including background history, and proposed project elements, design
criteria and any special items. This description should not exceed two
pages, and would provide the reader with an immediate overview of the
project.
There was very little attention paid to energy consumption or energy
recovery in most of the VE reports reviewed. VE teams should be urged
to take account of energy requirements and identify comparative
requirements. Energy recovery systems should also be investigated in
more detail to determine their cost-effectiveness in offsetting energy
demands.
The Designer's responses to the VE team's recommendations tended to be
long winded and often circumvent the subject. Responses should be con-
cise and as short as possible, commensurate with ensuring that the
response is understood. If the idea/recommendation is accepted, simply
write "Accept" for this item. Only items that are rejected need an
explanation.
There has been a wide variation of idea acceptance in the VE program.
Typically smaller, inexperienced firms reject ideas on the basis of
personal preference, less qualified opinions, and recommendations of
others. Larger, more experienced firms, tend to reject ideas because
they hold their own ability above that ofthe VE team. They also resist
changes to their standard way of design facilities. The VE team must
develop clear ideas that are well explained with examples of where and
how the ideas are to be implemented.
VE teams from the Design firm tend to be less critical of designs than
VE teams from different firms. There is probably a subconscious effort
not to make too many changes that would delay the design completion.
Their idea/recommendations tend to be minor in a possible effort to
avoid major changes.
Many firms appear to be completing the VE study simply because of the
EPA regulations, and not because of the advantages the program. It is
important for the Designer not to be "threatened" with a VE study, but
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.-- . . .
rather be encouraged to utilize the VE study to design a better
project. . ,
There has been much discussion on the amount of information that should
be supplied to the VE team, it seems that too much information can and
does stifle the creativity of the VE, team. The ideal level of
.information would be that /which allows the proper development of
ideas/recommendations but does not overwhelm the team.
The experience of -the VE team is one of the most important features of
a successful VE study. Experienced participants bring broad and diver-
gent viewpoints to the workshop which results in an ability to effec-
tively identify high cost areas and then cost out the alternatives. It
is more important to have experienced engineers on the team than to
require that all team members have attended the 40 hour training work-
shop. Typically, a firm sends the younger less experienced engineers to
these schools, but they don't have the necessary experience to maximize
the benefits of the study. The VE team coordinator needs the ability to
direct __the_ team's conduct, ensure that they keep on track, and main-
tains a positive, creative attitude at the workshop,.
Thrt v^; team members should be carefully selected for each specific pro-
ject. Workshops ;:.).-.. lucted with relatively inexperienced people resulted
in poor reports. The discipline and experience of team members should
be dictated by the timing of the workshop. Early workshops require more
process or conceptual oriented participants while later workshops
require more design and operation engineers.
A workshop tends to be. less creative when the team includes a large
number of members from different firms.; Team members tend to be
restrained in the presence of engineers from other firms. This is prob-
ably due to the unknown ability of other engineers and therefore there
is a certain degree of distrust. However, after working together on a
couple of projects, these imaginary barriers are removed and the VE
team functions efficiently.
Designers frequently take the ideas/recommendations personally. There
is a great deal of "pride of authorship" in the designs and the
Designers naturally "defend" and finds excuses for the manner in which
they designed the facility or item. As the program becomes more
accepted, there should be less of a defensive attitude and more of a
cooperative attitude.
There needs to be a greater, participation in the VE process, and espe-
cially the workshops, of staffs from regulatory agencies. This partici-
pation would demonstrate a commitment to the VE program and provide
them with a better understanding of wastewater facilities design. This
participation would increase the regulatory agencies effectiveness in
reviewing various wastewater projects. The agency representative pref-
erably should not be one of thetproject reviewers.
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The constraints imposed on a VE team should be listed and explained
prior to the start of a workshop. This will increase the quality and
acceptability of the teams recommendations.
Communications between the Designer and the VE team are an important
element in the success of a VE study. It is important that the VETC
establish positive communication between the Owner, the Designer and
the VE teams at the earliest possible date. The VETC should develop a
"rapport" with the Designer and avoid an antagonistic approach.
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APPENDIX B
IDEAS APPLICABLE TO MOST WASTEWATER TREATMENT PROJECTS
During the review of the 93 VE workshop reports, many of the ideas pre-
sented could be called "good design practice". These ideas addressed items that
were inadverently overlooked in the formulation of the initial design. These
design features are applicable to most wastewater treatment facilities. '
The design of wastewater treatment facilities requires anticipating poten-
tial problems; having a sensitivity to the site in terms of engineering and
environmental issues; recognizing and including the many details for cqnstruct-
ability and operability; and coordinating all component parts in order to achieve
a cost-effective, easily operable and convenient treatment facility. It is the
intent of this chapter to identify and briefly describe some of the items that
should be considered during the design phase and in VE workshops. These items may
seem obvious to most designers, but they were not included in many of the VE
reports reviewed during this study. The items are presented under the following
general categories: s' -.....-
ป Design Criteria
e Site Work and Layout
Site Buildings
Structural
ฎ Equipment
ฎ Mechanical
ป Electrical
ฎ Energy conservation
ซ Miscellaneous
DESIGN CRITERIA
1. Influent Design Data. Ensure that the wastewater treatment plant has been
designed for the maximum day influent wasteloads.
2. Design Criteria of Unit Processes. Review the design criteria for each unit
process to ensure that it is sized within acceptable limits.
3. Hydraulic Profile. Review the hydraulic profile to determine whether or not
any intermediate pumping stations can be eliminated to save energy. Also,
ensure that sufficient head exists across the plant to pass the peak hydrau-
lic flows during the 100 year flood condition. -
4. Unit Selection. Ensure that a complete economic analysis has been completed
before selecting individual unit processes. The economic analysis should
include both capital and operation and maintenance costs of the system and
an evaluation of the effect the system may have on other processes. For
example, the effect of recycle streams from thermal sludge treatment
processes on the biological treatment process; or the effect an enclosed
aerated grit chamber may have on the air handling system compared to a non-
aerated system.
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5. Unit Process Selection. Consider and evaluate all types of processes that
perform the same function, such as circular vs rectangular vs square
sedimentation tanks, or the different types of aeration devices.
SITE WORK AND LAYOUT
1. Access Roads. Ensure that roads maintaining the same functional access are
located in a manner that minimizes the length of roads in order to save
capital and maintenance costs.
2. Road Widths. Road widths should be commensurate with the projected traffic
volumes. Table B-1 shows recommended widths.
TABLE B-1. RECOMMENDED ROADWAY WIDTHS
Design
speed
(xnph)
20
25
30
35
Notes : 1
2.
3.
Total roadway width, including shoulders (feet)
Little traffic Frequent traffic
Few trucks Many trucks Few trucks Many trucks
and buses and buses and buses and buses
18 20 22 24
20 22 24 26
20 22 24 26
22 24 24 26
Maximum pavement width is 24 feet; wider roadways include snouxaers.
"Little" or "Frequent" farm machinery traffic is at the designer's
discretion.
Percentage of trucks and buses is defined by average daily traffic:
ADT up to 50 vehicles - Low percentage is less than 28%
ADT 51 to 100 vehicles - Low percentage is less than 12%
ADT 101 to 200 vehicles - Low percentage is less than 7%
ADT 201 to 400 vehicles - Use high percentage figures only
American City & County: January 1980
3. Road Design: Evaluate the climatic conditions of the area, and ensure that
the road bed to accommodates these conditions in combination with the pro-
jected traffic loads. It is frequently better to install a higher cost road
initially to reduce future maintenance costs.
4. Fencing. Fencing around the plant site should be reviewed for quality and
quantity. Areas that will be used for future expansion may not require
fencing. Fencing materials should be consistent with area in which plant is
located. Rural sitings may ony require wire barriers; whereas urban areas
may require high security fencing consistent with local aesthetics.
5. Yard Piping. The location of influent/effluent piping, transfer piping and
recycle piping should be examined in an effort to minimize the length
requirements. Pipe sizes should have acceptable velocity ranges to maintain
B-2
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solid suspension. In confined "areas piping should be sized for projected
ultimate flows. Wherever possible, the Return Activated Sludge/Was.te Acti-
vated Sludge piping systems sho.uld be simplified with common discharge pip-
ing and suction headers as much as possible.
6. Landscaping. Review landscaping plans with maintenance requirements in mind
For example, inclusion of sprinkler systems in arid areas and minimize area
covered. Use ground cover such as bark, chips or gravel as this doesn't
require the attention of other plantings. Select plantings and grass that
are suitable for the area, and require the least amount of care.
7. Site Layout. Locate proposed unit treatment processes in as compact a layout
as possible. The more compact plants require fewer operator steps and
shorter connecting piping.
8. Tunnels. Long lengths of underground tunnel should be eliminated unless they
are constructed in conjunction with other structures since above ground
walkways are often less expensive.
9. Handrails. Handrailings around certain open tanks or basins may be replaced
with either chain link fences or, narrow concrete walls at lower unit costs.
Tank walls can be utilized as the handrail by either bringing the walls up
above the ground surface as appropriate (42-inches)', or importing less fill
for the site. Either of these alternatives could be used to yield an
aesthetically pleasing appearance, and meet present OSHA standards. .
10. Site Lighting. Site lighting needs should meet functional requirements. If
security and full coverage lighting is required, consider high efficiency
light fixtures. :
SITE BUILDINGS ' l '
1. Buildings. Buildings of similar environmental conditions should be grouped
together to take advantage of common ..wall construction, less heating, and
more efficient movement and access between the different zones. '.:',-
2. Building Space. Review space requirements for the specific plant. After
making allowances for future expansions, any non-functional space may be
deleted. ; ,"'
3. Building Materials. Evaluate available building materials to assure that the
buildings use the most cost effective materials.
4. Building Architecture. Architectural finishes and materials should be
selected to minimize construction and maintenance costs. Construction mate-
rials should be commensurate with the specific building's function, such as
administration building compared to sludge handling building.
5. Buildings. Evaluate the potential for centralizing operations processes.
Duplication of similar process around "the site may be combined, such as one
-"''" blower building. Assure access for 'equipment maintenance and removal. The
B-3
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location and size of doors and windows should allow for equipment handling
devices. Assure that adequate aisleways and clearances is provided for
equipment and electrical panels. Evaluate energy requirements of materials
in the exterior walls.
6. Roofing. Roofing systems are the most frequent cause of claims and litiga-
tion in construction. Roofing systems should be reviewed strictly for per-
formance in the geographical area.
STRUCTURAL
1. Forming. Form work is generally the most expensive part of cast-in-place
concrete. Complex forming for concrete tanks, basins or buildings should be
minimized to reduce unnecessary construction costs.
2. Foundations. Review the geotechnical report for the proposed treatment
facilites to evaluate the foundations for required structures.
3. Slabs. Review alternative methods for designing the thickness of basin bot-
tom slabs. Consider slab-on-grade with minimum load transfer capability.
4. Groundwater. Evaluate groundwater levels at the site of the treatment facil-
ities. Review the uplift forces associated with structures and basins and
the placement of pressure relief devices.
5. Walls. Basin and tank walls design should minimize concrete/steel require-
ments. Walls for water retaining structures require special attention to
minimum cover over steel and other construction details to ensure a water
ti ght s truc ture.
6. Materials. Evaluate construction materials for compatibility with the antic-
ipated environmental conditions. Structures over high humidity areas, such
as over clarifiers or aeration basins, should be carefully evaluated since
steel members may require exotic coatings.
EQUIPMENT
1. Pumps. Consider the proposed application of the type and size of pumps. For
example, closed itnpellor pumps would not be used for fluids that contain
sludge or other solids.
2. Pumping Systems. Evaluate the potential for combinating pumps for optimum
operations. A standby unit should be included to provide for failure or
maintenance. Consider the mix of constant and variable speed pumps to min-
imize both capital and O&M costs.
3. Bearings. Evaluate the bearing life for equipment such as clarifier mech-
anisms, surface aerators or others, that typically are used continuously.
4. Gearboxes. When reduction gear boxes are required for equipment operation,
such as for surface aerators, evaluate the impact load capability.
B-4
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Frequently, these systems experience severe shock loads (due to transient
loads) that are substantially higher than the rated motor horsepower.
5. Standby Units. Consider utilizing flow equalization storage in lieu of
installing standby equipment throughout the plant. This may not be practical
for large treatment facilities, but a simple economic analysis can quickly
demonstrate the feasibility.
6. Equipment Units. Evaluate.the potential for optimizing the number and size
of each type of equipment item used in the treatment process. Normally,
-;. fewer items of equipment will result in lower O&M costs without unduly
affecting flexibility and reliability.
MECHANICAL . .' '
1. Valves. Plug valves should be used for wastewater and sludge lines. These
.valves seldom clog and are self-cleaning which- results in lower O&M
requirements.
2. Pipe Materials. Evaluate the use and location of the piping pipe materials.
Less expensive pipe often can be used where ductile iron or steel pipe have
been used historically.
3. Floor Drains. Floor drains should be installed in all buildings and struc-
tures. Water may be caused by equipment drainage, pipe rupture, washdown
practices or spills.
4. Clean Outs. All sludge piping should have cleanouts. Consider including sim-
ilar maintenance features on all other wastewater lines.
5. Ventilation. Ventilation systems should be capable of removing heat from
operating equipment and providing a safe environment for plant personnel.
6. Pipe Flexibility. Sufficient flexible couplings should be installed in the
piping system so that equipment, pipe and valves can be removed.
7. Vibration Isolators. Vibration isolation dampers should be included for all
high speed or large equipment items.
8. Acoustics. The estimated noise levels in all equipment rooms should be eval-
uated to determine if sound attenuation materials is needed to reduce the
ambient noise levels.
ELECTRICAL, INSTRUMENTATION AND CONTROLS
1. Distribution. Evaluate the distribution voltage around the treatment
facility. Frequently 5kV or 15kV distribution values are cost-effective for
large sites. - ,
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2. Luminaires. Review the luminaires selected for lighting to determine if high
intensity discharge (HID) or low intensity discharge (LID) luminaires should
be used for large areas.
3. Motor Voltage. Examine the voltage selected for high horsepower electric
motors (200 hp and above). Frequently, 2,300 volt or 4,000 volt motors are
more cost-effective than 460 volt motors since capital and operation and
maintenance costs tend to be lower for the higher voltage motors.
4. Variable Speed Drives. Evaluate the necessity of variable speed drive
installation in the treatment facility. These are frequently installed in
locations that could be served by constant speed drives. Variable speed
drives typically consume more energy although the overall energy use at the
facility may be less.
5. Computer. Examine the total costs and performance reliability of including a
computer in the treatment facility. The analysis should include all costs
associated with operating and maintaining the computer, which requires
specialized technical abilities. Computer sytems are rarely justified on an
economic basis, and are often installed as a result of technical considera-
tions. Computer operation of a treatment facility has been shown to reduce
operational labor requirements up to 40 percent, but maintenance costs may
offset this saving. Computers have proven to be effective for administra-
tive purposes and for scheduling and tracking maintenance requirements. The
size/capacity of the computer is directly related to the number of interface
points, which many times include points for analytical data which are
rarely, if ever, used.
6. Control. Evaluate the process control system's ability for manual control
and monitoring of the facility since all systems will inevitably go down for
one reason or another.
ENERGY CONSERVATION
1. Recovery of Anaerobic Digester Gas. Digester (sewage) gas can be used as the
fuel for space heating, digester heating, on-site generation of electricity,
engine driven pumps or blowers, or any other in-plant purpose requiring
fuel. Another alternative for larger facilities is to clean and sell the gas
to local industry or a gas company as low heat fuel.
2. Waste Heat Recovery. Recoverable waste heat is often generated by engines,
blowers, compressors, and furnaces or incinerators. Specially designed heat
exchangers can be installed to use waste heat for space heating, to supple-
ment anaerobic digester heating requirements, or other similar purposes.
3. Cogeneration. Cogeneration is the concept whereby electricity generated
on-site is supplied in parallel with the main outside power source. Any
excess electrical energy generated flows back into the power company's dis-
tribution grid, while electrical needs in excess of the amount generated is
supplied by the power company. This type of system is generally applicable
to areas having high electrical costs and for medium to large capacity
treatment plants.
B-6
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4,
Heat Pumps. Some of the heat contained .in sewage effluents can be recovered
through the use of heat pumps. Water to water or water to air may use the
effluent as either the heat source of sink. These systems can be used for
space heating or cooling, of a low temperature water loop or to pre-heat
fluids that are to be heated to higher temperatures.
5.
Active Solar Collection: This type of system requires'that a
(air, water or a water/glycol mixture) be continuously pumped
collectors to adsorb solar energy (heat) and then to a storage
tank of water, bed of rocks or some combination) to release
heat. These systems can be used for space heating and cooling,
and to supplement anaerobic digester "heating requirements.
working fluid
through solar
system (large
the absorbed
water heating
6.
Passive Solar Collection: These differ frpm the active systems in that there
are few moving parts and little equipment is required. They are used nor-
mally to augment space heating requirements. Typically, the system consists
of translucent panels of glass,'plastic or fiberglass separated from a heat
absorbing wall or panel by an air gap. Either the wall, or the air in the
air gap, or a combination of the two is heated 'from the sun's energy passing
through the translucent panels which in turn augments the space heating.
MISCELLANEOUS :
1. Corrosion. Evaluate the corrosive potential of the soils at the plant site
and the suitability of the materials.
2. Security. Consider the security needs of the treatment facility and evaluate
the measures necessary to ensure that security level.
,3. Storage. Evaluate the specific locations of the storage areas and. their
ability to adequately protect the stored items.
4. Odor Control. Review the odor potential from all areas of the treatment
faciliites and evaluate any possible public relation problems. " "
* U. S. GOVERNMENT PRINTING OFFICE 1980 - 677-094/1126 Reg. 8
B-7
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