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EXHIBIT B

PRIMARY AND SECONDARY DIGESTERS CLEANING
IFB0285-083117

SCOPE OF WORK

The Nashua Wastewater Treatment Facility (NWTF) is a 16 MGD (design capacity) that
normally operates at around 11-12 MGD during dry (no rain) conditions. The plant has a 1.3
million gallon (MG) primary digester and a 0.25 MG secondary digester. Attached are more
details on the primary and secondary digesters. These digesters were last cleaned out in 2006
and 2013, respectively. Both digesters are in need of complete cleaning. This bid will result in a
service contract awarded to the lowest responsible bid provided the bidder can meet the
minimum requirements set forth in the bid document.

The NWTF uses a blended sludge of approximately 60% primary and 40% secondary solids to
feed an anaerobic digester which stabilizes and reduces the volume of solids entering. The
primary digester is an egg shaped steel vessel where the majority of the sludge digestion and gas
production occurs. It overflows after an approximate 15-day retention time to an adjacent
secondary digester of much smaller volume.

In addition to cleaning out both the primary and secondary digesters, the contractor will be
required to dewater incoming primary and secondary sludge to the plant while the digester is
being cleaned. The scope of work involves the contractor providing sludge pumps, hoses,
portable centrifuge, screening, and container boxes to hold sludge & screenings for both
digesters and incoming sludge.

The contents of the secondary digester should be dewatered first so that the sludge can be
dewatered and meet class B sludge for land application. However, the sludge in digester has
more inorganic material (mostly grit and ground up plastic material) and should be screened to
remove the inert object. This sludge will be removed by NWTF’s biosolids truck hauler, Casella
Organics.

The NWTF contract with Casella is to haul off Class B sludge. Additional costs for Casella to
remove non-class B sludge are being negotiated between. The NWTF will arrange to have all
sludge produced during the dewatering process removed by Casella. The contractor is expected
to have the capability to transport dewatered sludge from the dewatering equipment to trailers
provided by Casella. The contractor shall work closely with Casella and plant management on
informing and scheduling the removal of full trailers.

Page 1 of 6

EXHIBIT B

Sequence of Operation

The sequence of operation stated below is based on information from the past digester cleaning
and plant knowledge on it. The goal is to dewater the sludge in the digesters and incoming
sludge in the shortest time possible while meeting all permit requirements. Should a contractor
have a better method to conduct the dewatering it should be discussed with NWTF plant
management and a new procedure may be developed. In addition, the sequence stated below is a
guideline and is subject to change if a better method or any obstacle, such as pump failure,
prohibits or changes how a step is to be conducted.

One week prior to starting the NWTF will dewater the secondary digester to the
extent possible.

At start the sludge holding tanks will be lowered as much as possible to allow for
incoming sludge.

Contractor shall setup dewatering equipment to dewater incoming sludge from the
sludge holding tanks.

Contractor shall setup dewatering equipment for dewater sludge in the primary and
secondary digesters.

Prior to start of dewatering the primary digester the remaining contents in the
secondary digester shall be screened and dewater. A much of the material possible in
the bottom of the secondary digester shall be removed. This will involve opening the
manway and hosing/diluting heavy material as the base so it can be pumped to
dewatering equipment.

Following cleanout of secondary digester, the NWTF will open valves and fill the
secondary digester. The cleanout of the primary digester will occur by transporting
sludge from the primary tank to the secondary tank.

The primary digester will be pumped out as much as possible. Once all the sludge
that can gravity feed to the secondary digester is complete the remaining sludge in the
bottom of the digester will be drained back to the sludge holding tanks or an influent
sewer manhole per direction by the NWTF. The final cleanout of the primary tanks
may require flushing water from the plant water system following proper aeration of
the vessel from the top man entry opening as described in step 8.

Gas flow valves from the primary digester will be closed and the manway hatch at top
opened. Contractor shall monitor levels of carbon dioxide and methane in the tank,
follow all OSHA regulations pertinent to ventilation needed for an explosive gas, and
ensure continuous gas monitoring throughout the inspection. Once determined it is
safe to enter, the contractor will inspect the inside of the structure using a camera.
The contractor shall have his own camera equipment or subcontract it to a sewer
video company. Camera shall have sufficient cable to be lowered to carefully inspect
the base area of the tank, about 100 feet deep from top to the bottom of the conical
section below grade. Pictures taken or videos shall be clear so that plant personnel
can review it and decide if any correction action is needed.

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EXHIBIT B

Once the primary digester has been cleaned out and inspected, it will be brought back
on line. The remaining 200,000 (+/-) gallons in the secondary digester may be
pumped back to the primary digester for potential use as feed sludge for the primary
tanks if found suitable for seed sludge (NWTF will test the sludge and make this
determination). Should be sludge remaining in the secondary digester be found not
suitable for seed for the primary digester, it will be dewatered per direction by the
contractor. If the sludge is found to be suitable, it shall be screens and pumped back
to the primary digester.

As soon as incoming sludge is being fed back to the digester, the dewatering
operation of the incoming sludge will cease. Similarly, there will no further
dewatering of the primary or secondary sludge so that operation will cease.

Page 3 of 6

EXHIBIT B

Nashua Wastewater Treatment Plant Responsibilities

The NWTF will cither provide 480V, 3 ph, 100 amp service or a portable generator

capable of providing this power.
The NWTF electrician will connect the contractor’s equipment to the service connection

or portable generator.

Plant water (non-potable) will be available to use from nearby yard hydrant(s). Water
pressure is around 100psi. NWTF will provide hoses and nozzles for contractor use in
cleaning and diluting as necessary.

The NWTF will dewater the secondary digester to the extent possible prior to start of
dewatering by contractor.

The NWTF will transport sludge from the primary digester to the secondary digester to
the extent possible.

Page 4 of 6

F. Nothing contained herein shall be construed as relieving the Contractor of any of his
responsibilities for protection of persons and property under the terms of the Contract.

G. Should it be determined by the Engineer that uniformed officers are not required;
flaggers will be provided to maintain traffic flow.

5. Care and Protection of Property

The Contractor shall be responsible for the preservation of all public and private property,
and shall use every precaution necessary to prevent damage thereto. If any direct or
indirect damage is done to public or private property by or on account of any act, omission,
neglect, or misconduct in the execution of the work on the part of the Contractor, such
property shall be promptly restored by the Contractor, at his/her expense, to a condition
similar or equal to that existing before the damage was done, to the satisfaction of the
Engineer.

6. Protection and Relocation of Existing Structures and Utilities

A. All existing buildings, utilities, pipes, poles, wires fences, curbing, property line
markers and other structures must be preserved in place without being temporarily or
permanently relocated, shall be carefully supported and protected from damage by
the contractor. Should such property be damaged, it shall be restored by the
Contractor, at no additional cost to the Owner.

B. The Contractor shall determine the location of all underground structures and utilities
(including existing water services, gas lines, drain lines, electrical lines, and sewers).
Services to buildings shall be maintained, and all costs or charges resulting from
damage thereto shall be paid by Contractor.

C. On paved surfaces the Contractor shall not use or operate tractors, bulldozers, or other
power-operated equipment with treads or wheels which are shaped so as to cut or
otherwise damage such surfaces.

D. All property damaged by the Contractor's operations shall be restored to the satisfaction
of the Engineer to a condition at least equal to that in which it was found immediately
before work was begun. Suitable materials and methods shall be used for such
restoration.

E. Restoration of existing property and structures shall be carried out as promptly as
practicable and shall not be left until the end of the construction period.

7. Maintenance of Flow

A. The Contractor shall at his own cost, provide for the flow of sewers and drains
interrupted during the progress of the work, and shall immediately remove and
dispose of all offensive matter. The entire procedure of maintaining existing flow shall
be fully discussed with the Engineer well in advance of the interruption of any flow.

2022 Sewer Replacement Project Control of Work and Materials
Nashua, NH 01110-3

EXHIBIT B

Tank Specifications and Relevant Information

1. Primary Digester (constructed in 1999)
Elevation at top of structure — 104.5 ft
Elevation at bottom — 10.75 ft
Elevation at ground — 30 (+/-) ft
Height from ground to top of structure — 74.5 (+/-) ft
Depth of structure below ground — 19.25 (+/-) ft
Shape — Egg
Material — Steel, insulated with fiberglass wrap on outside
Liquid Height — 97 (+/-) ft
Diameter (maximum) — 67 (+/-) ft
Volume — 1,300,000 gal (maximum)

2. Secondary Digester (constructed in 1999)

Elevation at top of structure — 54 (+/-) ft
Elevation at bottom of tank — 23.7 ft
Elevation at ground — 30 (+/-) ft

Height from ground — 24 (+/-) ft

Shape — cylindrical, conical below grade
Material - Steel (not insulated)

Design liquid height — 13 feet (above ground)
Diameter — 60 ft

Volume — 2750,000 gal (maximum)

3. Sludge Storage Tanks
Number of tanks — 5

Location — north end of Process Building (adjacent to sludge dewatering)
Elevation at top of tank — 50.5 (+/-) ft

Elevation at bottom of tank (low point) — 20 ft

Elevation at ground — 32 (+/-) ft

Height from ground — 18.5 (+/-) ft

Shape — rectangular

Tank Dimension — 14ft x 28ft, depth — 25 ft

Material - concrete

Volume per tank — 46,300 CF

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EXHIBIT B

Page 6 of 6

City of Nashua, New Hampshire
Division of Public Works

Primary and Secondary Digestor Cleaning
Addendum 2 - Revised August 28, 2017

EXHIBIT C

BS - 1 of 2

a Quantity Units Item Description Unit Price Total Price
1 1 LS ___|Mobilization $19,110.00 $19,110.00
2 200 dry tons |Dewater contents of primary and secondary digester

(minimum of 28% cake) $389.00 $77,800.00
3 1 LS ___|Interior cleaning/inspection of secondary and

primary digesters $5,300.00 $5,300.00
4 400 dry tons |Dewater incoming primary and secondary sludge

(minimum of 28% cake) $309.00 $123,606.00
5 1 LS ___/Crane Costs $5,200.00 $5,200.00
6 1 LS __ |Portable Generator and Fuel $6,300.00 $6,300.00

TOTAL BID PRICE FIGURES $237,310.00

Contractor:

Date:

Address:

Phone:

Fax:

Email Address:

TOTAL BID PRICE WORDS - BASE BID

Two Hundred Thirty-Seven Thousand Three Hundred Ten Dollars and

Zero Cents

Denali Water Solutions, LLC

SL/L Of, J Drews Oflan.

Authorized Signature:

r
2-28 -/ 7
3308 Bernice Avenue, Russellville, AR 72802
(479)-498-0500 Local{ 413)-530-4386

Local (413)-247-9657

dohara@wecareorganics.com
ae Se Eee

BS - 2 of 2

3308 Bernice Avenue

Russellville, AR 72802

PO Box 3036 = Russellville, AR 72811
Phone: 479-498-0500

tas Aen
a VA : E a

September 4, 2017

City of Nashua, New Hampshire
229 Main Street
Nashua, NH 03060-2019

RE: Primary and Secondary Digesters Cleaning
IFB0285-083117

Denali Water Solutions is pleased to submit the enclosed bid to provide the referenced services
at the Nashua Wasterwater Treatment Facility at 2 Sawmill Road.

Attached please find the Bid Bond requirement of 5% of the total bid as requested.

Should you have any questions or need additional clarification, please feel free to call J. Drew
O’Hara, Senior Vice President directly at 413-530-4386 (cell). Also feel free to examine the
Denali Water Solutions website at www.denaliwater.com which has additional information.
Denali Water Solutions appreciates the opportunity to submit the enclosed bid.

Respectfully Submitted.
DENALI WATER SOLLUTIONS, LLC

jhe OK me

A
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J. Drew O’Hara

Vice President — Dredging and Dewatering