ITEM 1 WWTF ExpansionITEM 7
tsTY OF
MINNESOTA
MEMORANDUM
TO: Public Works Subcommittee
FROM: Lori Johnson, City Administrator
DATE: October 16, 2015
SUBJECT: WWTF Expansion
As previously planned, Scott Schaefer of AE2S will be at our meeting to provide an update on
the WWTF Expansion project. Below are the main items of discussion at the meeting:
• East WWTF Biosolids Processes Capacity Analysis Tech Memo
• West WWTF Liquid Train Process Evaluation Tech Memo
• West WWTF Digester Alternatives and Recommendation
• Odor Control Bid Alternate
• Schedule and Next Steps
We are on schedule to bid the project early 2016 with substantial completion in fall of 2016. It
is important that any specific suggestions, issues, or concerns you have with the proposed
design and expansion plans be raised now before final design. Scott will go through design, bid
alternate(s), and timeline in as much detail as you want at the meeting to gather your input.
Additionally, the original project schedule included a check -in with the City Council before final
design; that meeting should occur soon to keep the project on schedule.
There is one other wastewater item staff has discussed and wants to inform you of before it
goes to City Council. In addition to this current project, the 2016 CIP includes a
recommendation to fund a WWTF Master Plan that is essentially a comprehensive engineering
study of future wastewater requirements and how to best meet that need from a citywide
perspective. It is important to plan now for future wastewater demands to secure additional
property if needed to accommodate plant expansion, to change the east/west flow before
development occurs in areas subject to change, and to begin financial planning to ensure funds
are available as future phases of expansion are built.
Table :L — opgngon of Fro[Uable Lonstructoon LOM — West WVV
01- UggeSler improvements
opinion of • • , a - Construction Costs
Otsego West WWTF
Drop
with Shear Tubes'
116,111W
Description
Cost
Mobilization, Bonds, Insurance
$100,000
$110,000
Site Work
$108,000
$113,000
Process Equipment and Piping (Includes Site Work Piping)
$693,000
$656,000
Structural
$263,000
$415,000
Architectural
$0
$0
Mechanical
$0
$0
Electrical/Controls
$183,000
$198,000
Subtotal
$1,347,000
$1,492,000
Construction Contingencies (15%)
$199,000
$221,000
Opinion of Probable . . .
4. 111
$1,713,000
Design Fee
$126,900
$126,900
Other Engineering, Legal, Admin (10%)
$154,600
$171,300
Opinion of Probable sCosts._,.,,,.__11
$2,011,200
Hr/- necummenud LIV11
Potential Bid Alternate Items
1) Additional Site Paving
2) Odor Control System
Table 2 — Net present Worth and Opinion of Probable O&M Cysts G oDesugw Flow (Basis)
Otsego West WWT
Description
-Net Present Worth and
Drop Pipe Diffusers
-
with Shear
Cost
O&M Costs
Labor
$16,000
$21,000
Power
$51,000
$78,000
Equipment Maintenance
$5,000
$5,000
Miscellaneous
$500
$1,300
Opinion of Probable Annual O&M Costs
$72,500
$105,300
O&M Net Present worth
Total
$993,000
ell
$1,441,000
/el
lAE2S Recommendation
zAn interest rate of 4.0% and 20 year period was used in the present worth calculations.
Note: Costs do not include potential Alternates or equipment replacement costs.
Otsego (Nest WWTF Digester Improvements Project Update: October 20, 2015
Table 3 e Alternatives
Advantages/Disadvantages
Drop Pipe
• Proven technology and experienced
® Additional costs
Diffusers
manufacturer in aerobic digestion
o New blowers
with Shear
applications
o New air piping
Tubes
a Cost-effective alternative
® Less control due to mixing and air
o New blowers in existing
dosing controlled by single piece of
structure
equipment
o No new pumps
® Proprietary
o Low footprint due to deeper
aerobic digestion tanks
o Lowest O&M
o Competitive net present worth
® Effective stabilization
Simple operation due to use of only
blowers
® New equipment (blowers) in single
location
Jet Aeration
® Proven technology in aerobic
Most expensive alternative
digestion applications. Experienced
o New blowers
manufacturers.
o New air piping
Effective stabilization
o New pumps
® Higher control due to mixing and air
o Expanded footprint for pumps
dosing controlled by independent
and flushing valve dry pit
equipment
o Highest O&M and NPW
® Multiple manufacturers
• More complex operation due to
header flushing
® New equipment (blowers and
pumps) in multiple locations
Table 4 m Future Capital Costs Prior to Design Flow
One million gallons (MG) of storage is currently available. To achieve 365
days of storage (no Spring hauling) at design flow/load capacity, additional
biosolids storage will be required ranging from 0.30 MG to 0.60 MG based
Biosolids $1.31VIM - $2.2MM on the performance of the new upstream aerobic digesters. Alternative
Storage for sludge storage biosolids disposal methods may also be considered in lieu (or in addition to)
biosolids storage expansion and require an in-depth analysis. Additional
storage volume can be deferred by hauling to other WWTFs during years
with a wet or cold Spring
Oxidation Additional off the shelf aerator as facility reaches 0.30 MGD (currently
Ditch $115,000 -0.25 MGD) would be required to meet current MPCA requirements for
Aerator redundancy. An entire new tank is not required to meet redundancy
reauirements.
Note: Table does not identify cost of replacing existing equipment, which is a typical cost of operating a
wastewater treatment facility. Equipment is typically replaced on a 15-25 year timeline at such facilities depending
on the equipment, environment, operation, and maintenance.
Otsego West WWTF Digester Improvements Project Update: October 20, 2015
Potential Schedule for:
Otsego WWWTF Digester
Project Starts
Show Weekends
Plan Duration by
Select Your View
1O
0.0
Project Preparation
AE25
w-- —
6-May-15 20
W.
1-Jun-15
13-May-15
13-May-15
21-May-15
26-May-15
26-Ma -15
0.1
0.2
0.3
0.4
0.5
Prepare draft digester improvements scrape
Scoping meeting
Revise scope/fee; additional meetings as required
Submit scope/fee for City Council Agenda Packet
City Council Meeting
AE25
City/AE25
AE2S
AE2S/City
City
6-May-15
13-May-15
13-May-15
21bMay-15
26-Ma -15
6
1
7
4
1
0.6
Assumed Notice to Proceed
City
27-May-15
4
1-Jun-15
1.0
Preliminary Design
AE25 with City
1-Jun-15
61
26-Aug-15
1.1
Preliminary Design activities
AE2S with City
1-Jun-15
30
10-Jul-15
6-Aug-I5
26-Aug-15
1.2
Equipment pre -selection or pre -procurement
AE25
10-Jul-15
20
1.3
Review meetings, revise, confirm with Council
AE25 with City
6-Aug-15
15
2.0
Final Design
City with AE25
26-Aug-15
65
25-Nov-15
2.1
Incorporate preliiminary design comments, detailed design
AE25
26-Aug-15
25
20-Sep-15
2.2
75% submittal, review, and review meeting
City with AE25
29-Sep-15
10
12-Oct-15
2.3
Bid document preparation
AE25
12-Oct-15
20
6-Nov-15
2.4
Final review, QA/QC
City with AE2S
6-Nov-15
10
19-Nov-15
2.5
2.6
2.7
Incorporate final revisions
Final City Council approval
Submit package to MPCA
AE25
City
AE25/City
19-Nov-15
25-Nov-15
25-Nov-15
5
1
1
25-Nov-15
25-Nov-15
25-Nov-15
3.0
Regulatory Review
MPCA
25-Nov-15
40
19-Jan-16
4.0
Bidding/Award
AE2S/City
19-Jan-16
40
14-Mar-16
5.0
1 Construction and Start -Up
lContractor
14-Mar-16
150
7-Oct-16
Printed/Updated 5/12/2015
AE2S