6.2. SR 09-15-2008^+//
Elk REQUEST FOR ACTION
River
To Item Number
Ci Council 6.2.
Agenda Section Meeting Date Prepared by
Public Works Se tember 15, 2008 Lori ohnson, City Administrator
Item Description Reviewed by
Engineering Services for Exploring Wastewater Treatment
Plant/Great River Energy Project Reviewed by
Action Requested
Consider authorizing engineering services to evaluate a possible Wastewater Treatment Plant/Great River
Energy project.
Background/Discussion
The City has a unique situation with the Wastewater Treatment Plant (WWTP) being located next to a
power generating plant. Both the City and Great River Energy (GRE) realize that there is potential in
cooperating on a project to use the sewer treatment operation to participate in generating electricity. This
idea has been discussed with GRE several times in the past; it appears that GRE is now in the initial stage
of exploring a project that could include working with the WWTP. Attached is a memo from Public
Works Director Terry Maurer that discusses the project in more detail. Obviously we axe very interested
in working with GRE to explore this project because of the potential long term benefits to the City.
In order to determine if the project is feasible, some engineering analysis needs to be done. Mr. Maurer
has identified a scope of work he feels is necessary for the City to evaluate this project opportunity. He
has requested a quote from BDM Engineers; the attached BDM quote states a maximum cost of $25,000
for this work.
Financial Impact
Up to $25,000 from the Waste Water Fund. This cost could potentially be recaptured in one year if a
cooperative project is feasible.
Attachments
^ Memo from Terry Maurer, Public Works Director
ACtlon Motion by Second by Vote
Follow Up
S:\Council\Lori\2008\WWTP GRE Project Eng Services.doc
MEMORANDUM
TO: Lori Johnson, City Administrator
FROM: Terry Maurer, Public Works Director
DATE: September 10, 2008
SUBJECT: WWTP Proposal for working with GRE
As you are aware, we have had several meetings with Great River Energy (GRE) over the
last several weeks looking at potential synergies between GRE's operation and the city's
Wastewater Treatment Plant (WWTP). GRE is anticipating the construction of a digester
for processing municipal solid waste. This digester will use the same technology that is
currently used at our Wastewater Treatment Plant. This will provide even more
opportunities to look for synergies between the two operations. Our hope from the WWTP
standpoint is to eventually get out of the sludge handling business. Currently, we store up to
700,000 gallons of sludge on site and twice a year, haul and spread it on the approximately
150 acres that the city owns near the YAC complex. If the city were able to get out of the
sludge hauling and spreading business by finding a method to ship sludge or undigested
waste to GRE for further processing, not only would it potentially save the city money in
our WWTP operations, but would also free up the sludge land for other uses. In addition,
looking for synergies has the potential of freeing space within our WWT'P which could
potentially be used for increasing the capacity of the entire plant.
After several meetings with representatives of GRE, myself, Gary Leirmore and Bill Chang,
our wastewater engineer, I have asked Bill to prepare a proposal for working with GRE to
further analyze the various options available. Bill has put together the attached proposal
estimated at a maximum of $25,000 for working with GRE engineers, dealing Minnesota
Pollution Control Agency relative to potential changes in our NPDES permit, and estimating
costs to evaluate cost-effectiveness of the various options that may be available to the city.
I would recommend that the city proceed with this study and continue to work closely with
GRE to evaluate options available to eliminate sludge hauling and spreading in the future.
Please let me know if you need any additional information to evaluate this recommendation.
S:\PUBLIC WORKS\Sewer Division\09 10 08 memo Proposal GRE.doc
Memorandum
Date: September 9, 2008
To: Terry Maurer, P.E.
.~-~
BDM
CONSULTIIVG ENGINEERS AND SURVEYORS, PLC
60 Plato Boulevard East; Suite 140
St. Paul, MN 55107
763-786-4570, Fax 763-786-4574
From: Bill Chang, P.E.
RE: Feasibility Study on WWTP Biosolids Incineration at Great River Energy
A. The City's Needs for Long Term Biosolids Disposal
The City of Elk River Wastewater Treatment Plant (WWTP) generates approximately
900,000 gallons a year (or 0.3 dry tons a day) of biosolids (sewage sludge} from its
wastewater treatment operation. The biosolids were treated at the existing anaerobic digesters
for pathogen reduction and land applied to the City owned farmland in liquid form.
In the past, the City pays approximately $25,000 a year to retain a contractor for liquid
biosolids hauling and land application. So far this year, the City has already paid $16,000 to
haul 400,000 gallons of biosolids as a result of the digester mixing problems. The total
biosolids hauling this year is expected to cost the City $35,000. In addition, the City budgeted
$50,000 this year for natural gas used at the WWTP, mostly to heat the anaerobic digesters.
With the rising fuel prices, these operating costs may continue to increase.
B. Potential Opportunities at Great River Enemy
Incinerate Sewage Sludge at Great River Energy
Great River Energy (GRE} operates an incinerator adjacent to the City's WWTP. Each day,
the incinerator consumes 1500 tons of municipal waste to generate 35 to 42 megawatts of
.electricity. The amount of sewage biosolids from the WWTP is insignificant as compared to
the mass of municipal waste burned at the incinerators. On May 29, 2008, we met with GRE
representatives and Gary Leirmoe to discuss the concept of incinerating municipal sewage
biosolids. GRE was interested in incinerating the sewage biosolids as a service to the City.
GRE would be interested in working with the city to advance this proposal.
2. Anaerobic Digestion of Municipal Solid Waste at GRE
GRE is currently exploring an innovative anaerobic digestion process which has successfully
been used by several European countries to convert municipal solid wastes into fuel. This
technology requires dilution water in the digestion process. GRE would like to evaluate the
feasibility of using the raw sewage sludge from the City's wastewater treatment plant, which
is mostly water, as the dilution water. If this innovative technology is feasible, the City may
eliminate the need for sludge disposal and the need for sludge treatment at its plant.
9/9/08
C. Feasibility Study Proposal
Memorandum
The concepts of sludge incineration or digestion at GRE appear to open an opportunity which
could potentially benefit the City of Elk River and GRE in both short and long term. To our
best knowledge, the City of Elk River is perhaps the only City in Minnesota where its
municipal WWTP sits right next to such an incinerator.
To further evaluate these two concepts, several environmental permitting .issues, operational
issues and fmancing issues must be addressed. GRE's current incineration permit only allows
the plant to burn municipal wastes. Adding municipal biosolids may require modifications to
the permit. The construction of anaerobic digesters at GRE may require a new permit. It could
also affect the City's WWTP permit.
The injection point of the liquid biosolids needs to be evaluated to minimise the exposure of
GRE's operators to the liquid biosolids and to diffuse the liquid inside the incinerators evenly.
The costs of pumping facility at the WWTP and piping from the WWTP to GRE incinerator
or digesters must be evaluated.
It is our recommendation that the City of Elk River authorizes a feasibility study on the
WWTP Biosolids Incineration or Digestion at Great River Energy. The recommended scope
of the study includes:
1. Projection of WWTP biosolids for the next 20 years.
2. Identify pending improvement needs for biosolids handling at the WWTP if the
City continues its land application for its WWTP biosolids.
3. Review applicable regulations and permit requirements with the MPCA for
incinerating sewage sludge or digesting sewage sludge at GRE. _
4. Provide information to GRE for their evaluation of the anaerobic digestion of
municipal solid waste using sewage sludge.
Evaluate the pumping facility at the WWTP, the options of piping routes from the
WWTP to GRE and the injection points at the incinerators or digesters.
6. Evaluate the level of biosolids treatment required at the WWTP prior to
incineration or digestion at GRE.
7. Provide cost analysis on the options of biosolids incineration or digestion at GRE
and the option of land application.
8. Discuss the funding options.
9. Develop an implementation plan and a project schedule.
The estimated engineering fee for the feasibility study is $25,000. Upon authorization, we
could complete the study in 3-4 months.
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