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NO MORE MONEY DOWN THE DRAIN!
DIVERTING FOOD RESIDUALS
FROM THE SEWER
By composting food residuals and
removing kitchen garbage disposals, Del Mar Fairgrounds
project sewer rate savings of $450,000 over the next ten
years.
Nancy
Strauss |
| MORE than three million persons visit the Del Mar
Fairgrounds in Del Mar, California each year, attending the
fair, National Horse Show and thoroughbred race meet. The 400
acres the fairgrounds - owned and operated by the 22nd
District Agricultural Association - also include a horse
boarding facility, golf driving range and tennis courts. The
district has an extensive waste reduction program that began
in 1985 with office paper recycling and now covers diversion
of food residuals from going down the drain (see "The Last 10
Percent Is The Toughest," January 2000). It's all part of our
staff's "zero waste or darn close" policy. |
| The largest amount of material diverted from
the landfill in animal bedding. On an annual basis, more than
18,350 tons are composted. The straw bedding goes to the local
mushroom farmer, and the shavings go to composting sites in
the San Diego region. The district purchases finished compost
from these same companies. |
| Preconsumer fruit and vegetable scraps are taken to the
vermicomposting site in the middle of the racetrack. The worm
castings are used on site for fertilizer. During the annual
Del Mar Fair, all the food vendors participate in the food
collection program. During the 20-day fair, approximately 40
tons of preconsumer food residuals are collected and hauled
off site to local composting sites. Eighty-nine percent of the
waste stream is diverted from the landfill and recycled or
sent to composting. |
| . |
| SEWER RATE REDUCTION |
| Richard Anthony of Richard Anthony Associates (RAA) in San
Diego, California brought the possibility of a sewer rate
reduction to our attention. From 1994 to 1998, Anthony was
program coordinator for San Diego County's Wastewater
Management Division. He was well aware of Del Mar's extensive
recycling and food residuals diversion programs and believed
we had a good chance of lowering our sewer rate. |
| "Redirecting the organics from the sewer to a composting
facility results in less suspended solids at the wastewater
treatment plant," explains Anthony. "This lowers plant costs
and increases its capacity to process sewerage. The Federal
Clean Water Act requires zero waste from sewer treatment
plants and calls for the sharing of treatment and disposal
costs based on the flow and strength of each generator's
sewerage." |
| Diversion of food preparation residuals has allowed
removal of garbage disposals from the kitchens and thus lower
waste use. Since the sewer bill is based on a strength
classification and water usage, removing the disposals saved
water and reduced solids. |
| . |
| TESTING FOR SEWER STRENGTH |
| A sewer sample was taken and tested from sewer strength.
It looked promising and we approached the city of Del Mar with
our concerns. The deputy general manager, Brad Gessner,
negotiated an agreement with the city that stipulated if the
district could prove the sewer strength was less than
previously assigned, the city would adjust the rate
appropriately and issue a refund for the previous 12 months
and reassign the strength at the new level. |
| The difference in classification is several milligrams per
liter for a shopping center (our choice) as opposed to a
restaurant with a bar. The city required the district to
complete ten separate tests during various times of the year.
RAA supplied us with the documentation needed to challenge our
sewer rates and the city agreed with the findings. |
| The results were overwhelming! They showed conclusively
that the district was misclassified for sewer strength, which
resulted in a 23 percent reduction in our sewer rate and
refund of $45,000 for the previous 12 months and projected
savings of $450,000 over the next ten years. Another benefit
will be additional capacity at the municipal wastewater plant
because of the diverted food residuals. This is just one more
reason to make food residuals a part of any waste reduction
program where food preparation takes
place. |
REDUCING SUSPENDED SOLIDS AND BIOCHEMICAL
OXYGEN DEMAND FROM COMMERCIAL SEWERAGE
| THE COUNTY of
San Diego (California) Department of Public Works (DPW)
manages and maintains four county sanitation districts
that discharge wastewater to the San Diego Metropolitan
Sewerage System (Metro) for treatment and biosolids
disposal. Because Metro receives funding from the
Federal Clean Water Program, all participating agencies
must meet requirements for sewer service charges based
on wastewater strength. To help customers with high
strength wastewater, the county and the California
Restaurant Association developed on educational program
to help reduce flows, strengths and costs. The county
and the association wanted to prove that source
separation and a separate collection |
program for food discards may be
effective means of reducing wastewater strength and
treatment, bakeries and other food handling
businesses.
In June, 1997, a countywide pilot
program was started to reduce strength and lower costs
associated with waste water treatment. The program
required routine maintenance of interceptors (large
multistage grease traps) and source separating food
discards from restaurants. In cooperation with the San
Diego Chapter of the California Restaurant Association,
the San Diego County Sanitation District conducted the
pilot program through September, 1997. The Department of
Public Works (DPW) staff sampled and analyzed effluents
from restaurants and other high strength user
groups. |
DPW staff tested the wastewater during
three intervals: Before the program began; After
education and grease trap/interceptor maintenance was
performed; and two weeks after the second sampling to
obtain consistent values. Wastewater strengths were
measured in terms of Biochemical Oxygen Demand (BOD) and
Total Suspended Solids (TSS) levels in milligrams per
liter of wastewater. District restaurants that
participated in a preprocessed food separation and
collection program reduced levels of BOD and TSS when
proper waste management practices in the kitchen were
implemented.
The test data provides
exciting environmental and economic incentives with the
application of a widespread food residuals diversion
program from the waste water stream to composting .
Sewer service charges for user groups listed by the
state as high strength generators could then be reduced
by removing the cause of strength and documenting the
new levels of TSS and BOD. The federal and state
requirements for a strength-based sewer service revenue
program would be met and the new classifications would
ensure fairness and equity.
|
Sampling results for restaurant
wastewater BOD and TSS.
| |
State
Standards |
Sample
1 |
Sample
2 |
Sample
3 |
| Restaurant |
BOD |
TSS |
BOD |
TSS |
BOD |
TSS |
BOD |
TSS |
|
| Applebees |
1,000 |
600 |
1,380 |
302 |
200 |
148 |
508 |
148 |
| Boston
Market |
1,000 |
600 |
280 |
52 |
200 |
152 |
29 |
177 |
| Bonita Golf
Club |
1,000 |
600 |
820 |
195 |
200 |
215 |
570 |
299 |
| KFC |
1,000 |
600 |
1,820 |
248 |
600 |
248 |
580 |
150 |
| Murietta's |
1,000 |
600 |
1,540 |
520 |
590 |
160 |
600 |
411 |
| |
Average: |
1,168 |
236 |
358 |
185 |
457 |
237 |
| |
Std: |
616 |
171 |
216 |
45 |
242 |
115 |
| |
Median: |
1,380 |
248 |
200 |
160 |
570 |
177 |
| |
Min: |
280 |
52 |
200 |
148 |
29 |
148 |
| |
Max: |
1,820 |
520 |
600 |
248 |
600 |
411 |
|
| Table
compares the results of three sampling analysis
for two fast food and three dine-in
restaurants. | | | |
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