HomeMy WebLinkAbout03/24/1992, 2C - BENEFICIAL USE OPTIONS FOR THE CITY'S MUNICIPAL SEWAGE SLUDGE - COMPOSTING AND AGRICULTURAL LAND APPLICATION '111 I1A��IY1111llfi'N�1III 1 city O f SA1 . -JIS OBISPO MEETING DATE
= u March 24, 1992
MIGe COUNCIL AGENDA REPORT ITEM NUMBEFI:A
FROM: William T. Hetland Prepared by: John Moss, Wastewater
Utilities Director Division Manager
David Zweig, Water
Projects Manager
SUBJECT:
Beneficial Use Options for the City's Municipal Sewage
Sludge - Composting and Agricultural Land Application
CAO RECOMMENDATION:
By motion, direct staff to proceed with the permitting and development of
sludge composting and sludge land application projects, to be located on City
owned property as shown in Figures one and two (attached).
DISCUSSION:
Purpose of Report
Sewage sludge reuse/disposal is a particularly difficult and sensitive problem.
Government regulations, public perception, aesthetic issues, and engineering issues must
all be dealt with effectively for a sludge reuse/disposal project to succeed. For this
reason, Council input is being requested early in the project development process.
Depending on the outcome of pending EPA regulations, the permitting of a sludge
disposal/reuse project may require considerable staff time and effort. It is also
recognized that there may be aesthetic concerns and competing uses for the
recommended project sites. For these reasons, specific direction regarding the siting of
the composting and land application projects is requested at this time.
Staff Suggestions
Staff suggests that while composting and land application permits are being pursued for
City owned sites, privately owned land application sites should also be pursued to meet
the City's immediate needs. It is also suggested that solutions to the City's sludge
disposal problem be developed "in house" by existing utilities staff.
Background
The City's Wastewater Treatment Plant currently generates approximately 2,000 cubic
yards (200 dump truck loads) of treated, dried municipal sewage sludge per year. One
and a half years production of sludge is now stockpiled at the treatment plant awaiting
disposal, and the stockpile is growing at a rate of nearly 40 cubic yards per week
Increasing regulation on disposal of sludge, as well as rising costs associated with
disposal, has prompted staff to re-evaluate past disposal practices. As a result of this re-
evaluation, it was determined that past disposal practices are either not available or not
feasible in the future, and new disposal methods must be developed. Staff has identified
several new sludge disposal/reuse alternatives which may lead to a reliable and cost
effective sludge management program for the City. The City currently has no means of
permanent sludge disposal.
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MEMO& COUNCIL AGENDA REPORT
The City has received a directive from the California Regional Water Quality Control
Board (RWQCB) to develop a long term sludge management plan. This report outlines
the plan options developed by staff. In general, the plan options emphasize a shift from
short term "disposal" practices, to long term "reuse/recycling" programs. This approach
is in compliance with AB939, the Integrated Waste Management Act, which directs
jurisdictions to plan for the reuse and long term disposal of special wastes such as
sewage sludge.
Past practices for disposal of the City's sludge included the following:
A. Give-away to residents of the community
B. Paying a minimal fee to a local fertilizer company or farmer to haul off the
sludge for use as a fertilizer
C. Disposal at the local landfill
D. Reuse of the sludge as an agricultural soil amendment on property in Santa
Barbara County
These past disposal methods are no longer available to the City or may not be desirable
for the following reasons: new regulations no longer allow give-away to the public
without additional treatment to further destroy harmful organisms; fertilizer companies
and farmers will no longer take sludge for a minimal fee because of more stringent
regulations; the local landfill is no longer permitted to accept municipal sewage sludge;
and, the high cost of transporting sludge out of the County is not economically desirable.
Additionally, out of County disposal of sludge may not be in keeping with State policy
for local disposal/processing of solid wastes.
Reuse/Disposal Options
Staff has investigated several sludge disposal options. The three most economically
feasible and environmentally sound options are discussed below.
OPTION 1 - COMPOSTING
Sludge composting is becoming increasingly popular throughout the U.S. as a means of
turning a disposal problem into a valuable product. A recent survey indicates 149 sludge
composting operations are on line in the U.S. with 126 more in the works. Composting
the City's sludge would involve mixing the sludge from the Wastewater Treatment Plant
with wood chips and cuttings generated by the City's landscape and tree crews. The
mixture would then be placed in six foot high windrows (berms) and left to decompose.
Composting the sludge/wood chip mixture will take a minimum of one month per batch.
During that time, the compost will have to be turned over periodically for aeration.
The process of decomposition generates heat, which in turn kills harmful bacteria and
viruses. When composting is complete, the sludge/wood chip mixture will appear to be
a rich, black, material similar to soil. The compost can be used for City landscape
projects, and given away or sold to the public if excess remains.
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COUNCIL AGENDA REPORT
The recommended site for the composting operation is a 3 acre portion of the field
south of the Wastewater Treatment Plant expansion (see attached figures 1 & 2). This
location is desirable from an operational standpoint because of its proximity to the
sludge, wood chips, and operations staff. The site would be properly screened and
landscaped. The draft Corp Yard Master Plan identifies this area as being suitable for
composting. A site previously considered by the Council for a small scale composting
operation is located between the Bus Yard and the Corp Yard. This location is no
longer recommended because it is not large enough for the full scale composting pilot
project now being considered.
It is envisioned that composting will begin as a temporary two-year pilot project. At the
end of two years, the project will be evaluated and then continued as is, modified, or
terminated. As a pilot project, the following permits and regulatory reviews will be
required:
A- Environmental Review by City Community Development Department
B. Issuance of Waste Discharge Requirements by the RWQCB
C. City Temporary Use permit
D. Solid Waste Facility Permit by County Health
The advantages and disadvantages of starting a sludge composting program are
summarized below.
Advantages of Com on sting
♦ Complies with RWQCB directive
♦ Costs are competitive with other disposal options
♦ In keeping with AB 939 - Reduces solid waste to landfill and reduces landfill
tipping fees
♦ Produces a beneficial product from a waste material
♦ Establishes a long term solution with predictable costs to disposal problem
♦ Provides a means to divert from landfill wood chips and green waste
generated by the City
♦ Reduced regulatory constraints
♦ Saves the cost of buying a similar landscaping compost used by the City
Disadvantages of Composting
♦ May require additional staff (1 part-time employee)
♦ May require the acquisition of some new equipment (tub grinder, windrow
turner)
♦ Requires use of trucks and loader currently owned by the City
♦ Requires approximately three acres of land
♦ Requires time commitment by staff to develop program
♦ If not carried out properly, may cause odor problems
♦ Operation may not be aesthetically pleasing to some individuals
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COUNCIL AGENDA REPORT
OPTION 2 - LAND APPLICATION ON CITY OWNED PROPERTY
Sewage sludge has been used for centuries as a soil amendment and fertilizer. Land
application not only serves as a cost effective disposal method, but it also serves a
beneficial purpose by enhancing the agricultural productivity of the amended land. The
proposed land application of City municipal sludge involves the following steps:
1. Spread the sludge in a one inch thick layer over several acres of relatively flat
land
2. Till the sludge into the soil using conventional farming equipment
3. Plant the site with pasture seed mix (or flowers or other non-food crop)
4. When the pasture is established, graze cattle on the site (or harvest crop)
5. Repeat, starting with step 1
This process may be repeated a maximum of 10-15 times, with each cycle taking one
year. The nitrogen introduced into the soil by this process will be used up by the
vegetation growing on the site. The only factor which limits the number of times sludge
may be applied to a given site is the gradual buildup of trace metals in the soil.
This problem will be avoided by carefully monitoring the soil, and terminating the
program after a maximum of 10 to 15 years, when the concentration of metals in the soil
is still well within the range of safety. RWQCB and Health Department regulations will
be followed at all times to ensure that the sludge application program has no harmful
affect on public health or the environment. After the sludge application program is
terminated, the land can be allowed to revert back to its original use. The sludge
application program can then be relocated to a new site.
Two possible City owned sites have been identified as being suitable for the land
application of sludge: 1) an 11 acre portion of the field south of the Wastewater
Treatment Plant expansion, and 2) a 17 acre portion of Laguna Lake Park (see attached
sketches). The site closest to the treatment plant is preferable, due to its close
proximity to the source of the sludge and operations staff. The draft Corp Yard Master
Plan identifies the aforementioned 11 acre site as being suitable for the land application
of sludge.
Land application of sludge at the proposed locations would most likely be accomplished
by leasing the site to a local farmer or rancher, with an agreement requiring the lessee
to participate in the sludge application program The City would arrange for the
delivery of the sludge to the site, and handle all monitoring and regulatory requirements.
The lessee would be responsible for spreading and tilling the sludge and growing a crop.
It is anticipated that the following permits and regulatory reviews will be needed for this
project:
A. Environmental Review by City Community Development Department
B. Issuance of Waste Discharge Requirements by the RWQCB
C. Site soils and groundwater monitoring
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ONGs COUNCIL AGENDA REPORT
The advantages and disadvantages of applying sludge to City owned land are listed
below:
Advantages of Land Application
♦ Complies with RWQCB directive
♦ Costs are competitive with other disposal options
• Serves a beneficial purpose as a fertilizer/soil amendment
♦ Establishes a long-term solution with predictable costs to disposal problem
Disadvantages of Land Application
♦ Requires use of trucks and loader currently owned by the City
♦ Requires several acres of land
♦ Requires time commitment by staff to develop, monitor and implement
program
♦ Operation may not be aesthetically pleasing to some individuals
♦ If at back area of Laguna Lake Park, will cause significant truck traffic load
on Park roads, and would have to be coordinated with proposed Laguna Lake
dredging program
OPTION 3 - LAND APPLICATION ON PRIVATELY OWNED PROPERTY
Option 3 is basically the same as Option 2, except the sludge would be applied to soil
on private ranches and farms. Currently, there are no permitted sites for land
application of sludge in San Luis Obispo County. For this option to be effective, City
staff would have to take the following steps:
1. Identify landowners interested in participating in a sludge application project
2. Enter into an agreement with the landowner and specify costs and
responsibilities
3. Assist landowner in obtaining necessary permits, or have City Staff obtain
permits
Permitted landowners in Santa Barbara County currently charge a substantial fee for
accepting sludge for land application. This fee is in addition to the cost of hauling the
sludge to the site. It is conceivable that if a new private site is developed with the '
assistance of Utilities Staff, an agreement can be reached with the landowner to accept
sludge at little or no cost, other than hauling expenses. If the landowner is made to
recognize sludge as a valuable soil amendment rather than just an inexpensive disposal
method for the City, a mutually advantageous partnership can be created between the
two parties.
One possible location for the land application of sludge is the La Lomita Ranch and
proposed Las Nomadas Golf Course project, south east of the City. The planners of the
project have already expressed their interest in utilizing municipal sludge as a soil
amendment. Other possible sites for land application could be found by contacting large
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Memo COUNCIL AGENDA REPORT
landowners in the area known to staff, and by requesting assistance from Department of
Agriculture personnel.
The advantages and disadvantages of land application of sludge on private land are
listed below:
Advantages of Land Application on Private Land
♦ Complies with RWQCB directive
♦ Costs are competitive with other disposal options
♦ Serves a beneficial purpose as a fertilizer/soil amendment
♦ Will not tie up use of limited City property
♦ Private sites may be located in more remote areas where aesthetic
considerations are less of a concern
i
Disadvantages of Land Application on Private Land
♦ Private owners may want to charge a fee to accept sludge
♦ Private ownership of the site may reduce the long-term reliability of the
project
♦ The City will lack control over current and future uses of the site
♦ Requires use of trucks and loader currently owned by the City
♦ Requires time commitment by staff to develop, monitor and implement
program
Possible City Owned Locations for Composting and Land Application
As mentioned earlier, there are basically two proposed City owned locations for sludge
reuse/disposal projects: 1) the fields south of the wastewater treatment plant expansion,
adjacent to the 101 freeway, and 2) a portion of Laguna Lake Park. There are Master
Plans for both of these areas now under development by the Community Development
Department. The attached sketches show project locations which have been identified
in draft versions of the Master Plans as being suitable for sludge reuse/disposal
operations. Due to the ever increasing quantity of sludge accumulating at the treatment
plant, Utilities Staff recommends that development of sludge reuse/disposal projects be
allowed to proceed concurrent with the completion of the master plans, if necessary.
CONCURRENCES:
The sludge disposal/reuse plan outlined in this report was developed with the input and
assistance of City staff in the Public Works and the Community Development
Departments. The City's Solid Waste Coordinator, Cynthia Butterfield, has expressed
her support for a sludge composting.project, and noted that such a program would divert
green waste from the landfill. Public Works Department staff indicated that heavy
equipment now assigned to Public Works could be utilized for a sludge reuse/disposal
project. Utilities staff met with Community Development staff to discuss the possible
siting of sludge disposal/reuse projects on City property. Although master plans for the
City owned sites being considered have not been finalized, preliminary
°u��'►►►��IIII�I��Nu�i�b�� city of San Luis OBISp0
MOGe COUNCIL AGENDA REPORT
indications from Community Development staff are that the Corpyard sites (Figures 1
and 2) will be acceptable, and the Laguna Lake Park site (Figure 1) may be acceptable.
Competing uses for the Laguna Lake Park site include 1) open space and 2) a lake
dredging disposal project.
FISCAL IMPACT:
There is no fiscal impact associated with the Council following the CAO
recommendation at this time. Based on the direction received from Council, specific
sludge disposal programs will be developed by staff and brought to Council for approval.
The City has most recently disposed of sludge through a contract with Bio-Gro
International. For a one time cost of nearly $280,000, Bio-Gro disposed of
approximately 3.5 years worth of sludge via agricultural land application in Santa
Barbara County. If the City were to continue to contract out sludge disposal in a similar
fashion, the cost would be $70,000 to $102,000 per year. This cost is based on proposals
received by the City in 1990 for reuse/disposal of approximately 2000 cubic yards of
sludge per year. These proposals entail hauling the sludge to permitted sites from
northern Santa Barbara County to as far away as Arizona.
Although detailed costs have not yet been determined for the three options described in
this report, it is estimated that any of the options (or combination of options) could be
used at a long-term operating cost of less than $50,000 per year. Some additional
capital expenditures to obtain necessary equipment and/or contracts for hauling and
spreading may also be necessary depending on program direction. On the other hand,
savings will be realized by the Public Works Department from reduced landfill tipping
fees (for green waste) and reduced costs for buying compost, if a composting program is
adopted by the Council. The major cost component in sludge disposal projects is
typically trucking expenses. For this reason, a sludge disposal/reuse project located
nearest the Wastewater Treatment Plant will be the most economical.
The City now pays approximately $120,000 per year in landfill tipping fees for all types
of trash and waste. Approximately 10-15% of the material disposed of in the landfill is
compostable green waste. The compost now used in City projects is purchased by
private contractors working for the City. The value of this compost has not been
determined at this time.
ALTERNATIVES:
As discussed above, the three recommended options for sludge reuse/disposal are 1)
composting, 2) land application on City property, and 3) land application on privately
owned land. To reiterate, staff recommends these three options be developed
simultaneously.
An alternative to the recommended options would be to contract to a private company
for a one time sludge removal. The private company would take responsibility for
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city o� san Luis OBISpo
COUNCIL AGENDA REPORT
determining the method and ultimate location of disposal. This alternative is not
recommended because it would not provide a long term solution to the disposal
problem, and it would probably be more costly than the recommended options.
A second alternative would be to contract with a consultant to study the City's sludge
disposal problem, and then have the consultant develop the chosen disposal program.
Several qualified consultants have expressed interest in performing this service. This
alternative is not recommended because it would probably be more costly than the
recommended options, and is unlikely to produce options significantly different than
those recommended by staff.
I
Attachments: Figure 1 - Location Map
Figure 2 - Detail of Corp Yard Sites
P/DU/SLUDGEREP
3/13/92
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