Subject: LA sludge-Judge
Date: 11/29/2006
To: James Burger jburger@bakersfield.com
Fm: Dr Edo McGowan
Re: LA sludge and heah come de the judge
This judge is grossly ignorant of the facts and thus has made a fairly large blunder with his decision. There are extant
recycling technologies that would obviate many if not all of the issues associated with sewage sludge, including its
transport costs and costs of running expensive ratepayer operated plants. Unfortunately, it appears that this judge was
not aware of these newer technologies or chose not to avail himself of a broader picture.
In your story, you note------------ Judge Gary Feess said he believes state laws that push for recycling of all solid waste
-- including sewage sludge -- take precedence over the Kern County ordinance that bans spreading treated human and
industrial waste on unincorporated land in Kern County.
If this man really believed this and was not just ignorant or politically tricked, he would have come to an entirely different
conclusion. Below is the reason why. With existing technology using fluid bed incineration, the sludge is removed before
entering the plant. This then is converted into biofuel and the return is about 85%. The gas has a better BTU quality
than natural gas. Thus this removal and energy conversion of sludge obviates risks associated with pathogens,
chemicals, endocrine disrupters and almost all else that is found in the sludge. By taking this off before it reaches the
treatment works this eliminates the need for much of the treatment work’s current physical structure. It also vastly
diminishes the solubleization of solids and sewer works are notoriously poor at handling materials in solution, hence
these pollutants would not reach the ocean or rivers. Further, the water coming out of the newer technology can be
recycled and thus used for many uses rather than discharge to the sea. Because the plant can be vastly reduced in size
and complexity, the need for expensive staff is greatly reduced, thus recycling ratepayer dollars. Because the material
that would be normally transported to Kern is now fuel converted to useable energy, all transport costs and
environmental air quality issues associated with transport are eliminated. Thus, how could this judge come up with his
rational?
What energy levels are thrown away by current sewer treatment activities? Here are some preliminary numbers. An
estimate of sludge generated per MGD of influent to the plant is about 3 tons and this will equate to about 8,000 cu ft of
methane (CH4). This can be summed for the LA basin and see what is lost by not recycling sludge into energy.
Loren Faundahl of the EPA's San Francisco office tells me that each ton of sludge (18% solids) will give off between
2,000 and 4,000 cu ft of CH4. Now about trucks hauling sludge---assume 1984 through 2000 vintage 60,000 to 80,000#
vehicles all on diesel. The average consumption of fuel is approximately 5 miles per gallon. NOx generation is
approximately 20g/mile (range 13-23). Thus to calculate the round trip generated amount would require destinations.
PM and CO2 are respectively 0.4 and 2000/g/mile.
Thus by eliminating sludge transport and converting sludge to energy, one can see considerable benefit. The almost
1/2 million tons transported from LA into the lower Central Valley is a major source of air quality degradation in the
Bakersfield area--an already oversubscribed air shed.
The conversion of CH4 then evolves into 21X that amount of CO2. That is what LA is putting into the Central Valley and
if one did a careful economic analysis of the impacts of reduced air quality, the cost might be an impressive number, all
because they are too ignorant to look at alternative recycling.
The following is based on data generated by a study, commissioned by the California Integrated Waste management
Board (CIWMB) and prepared by the University of California, Riverside’s College of Engineering-Center for
Environmental Research and Technology. The entire article can be read by obtaining a web copy from Forester Pubs,
the latest issue (http://www.gradingandexcavating.com/msw.html). The paper is entitled Evaluation of Environmental
Impacts of Theromchemical Conversion Technologies Using Municipal Solid Waste Feedstock. MSW Management,
Elements 2007
Vol 16, No 4.
Using this study as a model, I have merely substituted data but essentially used their methodology. In the case
presented, we are discussing the movement of about ½ million tons of sewer sludge from the Greater LA Basin into the
San Joaquin Valley for land application. Thus, I will look at the added air quality impacts in this case from
trucking and then the evolution of CH4 from that sludge. Please remember this is in essence a transfer of smog out of
LA and into the already oversubscribed air basin of Bakersfield.
It should be of some interest to also note that the wine industry of the San Joaquin Valley has been hit with an air quality
fee. Among the questions I raise here as an aside, is the subsidizing of LA sewage impacts by the Valley’s wine
industry—an obvious externality to the agricultural industry. This says nothing of reduced agricultural production caused
by increased air quality impacts. These costs are also external to production. Further, the issue of human health and
thus diminished desirability of the area will at some point begin to see economic consequences.
TRUCKING IMPACTS
Assume the following. 500,000 tons of sewer sludge is transferred from the LA Basin to the Bakersfield area. Over the
grapevine route assumes an elevation shift of about 4,000 feet. The trip from Hyperion to Bakersfield is about 100 miles
which will be our assumed one-way distance. The average truck is assumed to carry 25 tons and has an average fuel
consumption rate of 5-miles/gallon.
Thus far we can compute some data.
At 25 tons/truck, we will be making 20,000 trips to Bakersfield and back. That is 55 trips/day. At a round trip of 200 miles
this consumes 40 gallons of diesel. At 55 trips, this is 2,200 gpd or about 803,000 gallons of diesel per year.
Heavy Duty Diesel NOx Emissions
Cocker et. al. measured NOx emissions with a mobile laboratory that serves as the semi-trailer for a heavy duty diesel
truck-tractor (1). With a gross vehicle weight (GVW) of 60,000 lbs, NOx emissions averaged 20 g/mile for the 106-mile
round trip between Riverside and Victorville, CA (with an altitude change of 3,000 feet between the two cities).
Using Cocker’s data and substituting the Hyperion to Bakersfield run, we get the following (note the elevation difference
in our example is 1,000 feet more thus using Cocker’s example directly will be an underestimate).
CARB EMFAC gives NOx emissions from 13.4 to 23 g/mile for heavy duty vehicles manufactured between 1984 and
2002 (http://www.arb.ca.gov/msei/on-road/downloads/tsd/HDT_Emissions_New.pdf).
The hypothetical distance used by Cocker was 53 miles, (our one-way trip is approximately double that). From Cocker,
NOx emissions for a heavy-duty diesel truck (class 8) making this roundtrip will be approximately 2 kg (using an emission
factor of 20 g NOx/mile) (2). Assume a payload of approximately 25 tons (50,000 lbs. Maximum gross vehicle weight is
80,000 lbs). Thus based on this assumption, the 55 trips from Hypperion to Bakersfield and back will generate 110
pounds of NOx
PM and CO2 Emissions
From CARB EMFAC, approximate emission factors for PM and CO2 are 0.4 g/mile and 2000 g/mile respectively.
Therefore, the avoided emissions of diesel engine PM and CO2 due to MSW transport from the transfer station to
landfill are about 0.2.4 and 1200 tons respectively.
Evolution of Methane by Transferred Sewer Sludge
Assuming Loren Faundahl and her staff are correct that each ton of sewer sludge will produce on the average about
3,000 cuft of CH4. The roughly ½ million tons of LA Basin sewer sludge will produce 1.5 billion cubic feet of CH4 or 21
times that amount of CO2 will eventually evolve.
SUMMARY
From the above assuming assumptions, it should be clear that the transfer of sewer sludge from one area to another is
not without consequence. In preparing a proper economic analysis of benefits from the land application of sewer sludge
or its conversion via composting, the above externalities (this is just a short list) need to be backed out to obtain a more
accurate cost benefit analysis. Until such an economic analysis has been presented, it will be difficult to continue any
reasonable discussion of the merits of this activity.
Notes _______________________________
(Cocker, D.R.; Shah, S.D.; Johnson, K.; Miller, J.W.; and Norbeck, J.M. 2004. "Development and Application of a Mobile
Laboratory for Measuring Emissions From Diesel Engines. 1. Regulated Gaseous Emissions." Environmental Science
and Technology, 38[7Apr 1], 2182-2189).
(2) Cocker estimated NOx emissions for transporting solid waste from the transfer station to the landfill are, therefore,
0.1 lb/ton (0.046 kg/ton). The 129,780 tons of MSW no longer trucked to a landfill result in a reduction of approximately
6.1 tons of NOx emissions emitted to the atmosphere annually.
Next, we expand the discussion bu providing an estimate of sewer sludge generated through sewer plants currently
discharging to the marine environment from Monterey to the border with Mexico.
This material is somewhat redundant, but gives one some quantative data on what is not recycled by land application s
rather than as a biofuel.
Data were obtained by McGowan in circa 2002 through the San Luis Office of the RWQCB. Sewer sludge is the term for
the separated solids that are received by a sewer plant (POTW) from the municipal and industrial sewage flow. In
industrial areas, this includes discharges from industrial sources. It should be mentioned here that numerous toxic
materials are discharged by industry into sewers. Industry, through an exemption, is allowed to discharge up to 30
pounds of regulated toxins per month with out any requirement for reporting or pretreatment. Some of these are highly
toxic biotoxins.
The sewer processes based on current plant design send the entire suite of wastewater through a series of treatment
processes. Thus the dissolved as well as the solid materials that constitute sewage are subjected to microbial actions
that break down constituents into simpler components. The process also generates cellular structures (multiplication of
microbes in this nutrient rich environment), thus the end volume of solids exceeds that originally seen within the influent.
Further, because of the biological digestion, many of the solids are rendered into solution. POTWs as currently
designed are incapable of effectively dealing with dissolved materials. Thus these are sent with the discharge into the
environment at large. It is thus a gross misnomer to speak of treated wastewater, although it may meet current
standards.
These standards, however, actually meet but a fraction of the mandates of the Clean Water Act (CWA). If sewer plants
were actually to meet CWA requirements, it would require a complete redesign of almost the nation’s entire POTW
physical plant. This fact is conveniently ignored by regulators. The politics involved had been, until the present, beyond
the capacity of regulatory control. Current technology may change this picture, especially when combined with benefits
from a previously untapped renewable energy resource.
Note: the list below comprises POTWs located along the coast between Monterey and the US border with Mexico. Some
are named for the major city and others noted below are for a collective of towns within an area. Some of these POTWs
have very short and shallow outfalls and thus discharge to the surf.
Nonetheless, even with longer outfalls, the effluent may be entrained within the two major currents (northward-moving
warm water and southward-moving cold water that meet and form a gyre just off Santa Barbara. Thus, because these
two currents combine within a gyre, there is a concentration of toxins within this unique area. This area is one of two
unique points on the entire globe where this mixing occurs. Hence the species presented and their biodiversity are
found in only one other very unique global area. The potential contamination from discharged sewage and thus damage
to this unique marine bioregion has not been well studied or estimated.
Average Dry Weather Flow—Monterey to US border, including Tia Juana in MGD.
Monterey---------------------------------------------------------------9.1
Watsonville------------------------------------------------------------7.5
Monterey Regional------------------------------------------------ 29.6
Carmel/Pebble Beach--------------------------------------------- 1.6
Cayucus/Morrow Bay---------------------------------------------- 1.4
Avila-------------------------------------------------------------------- -0.03
Goleta------------------------------------------------------------------ 4.8
Santa Barbara-------------------------------------------------------- 8.5
Montecito---------------------------------------------------------------1.0
Summerland-----------------------------------------------------------0.15
Carpinteria------------------------------------------------------------- 1.7
Oxnard-----------------------------------------------------------------21.0
Hyperion-------------------------------------------------------------450.0
LA County----------------------------------------------------------- 350.0
Terminal Ils (LA City)----------------------------------------------- 30.0
Avalon--------------------------------------------------------------------0.6
San Clemente----------------------------------------------------------0.02
Orange County------------------------------------------------------320.0
Laguna Niguel & surroundings------------------------------------17.6
Capistrano Beach & surroundings------------------------------- 18.7
Oceanside & surroundings-----------------------------------------12.3
Encina & surroundings----------------------------------------------22.9
San Elijo & surroundings-------------------------------------------15.0
Pt. Loma (San Diego & surroundings)---------------------------17.0
South Bay (San Ysidro to & incl TJ, Mexico)-------------------29.0
Total average dry weather flow in MGD--------------1369.5
At an average influent sludge load of 3 tons/MGD, the average daily sludge tonnage contained with the wastewater is
estimated at roughly 4100. It must be remembered that even with secondary treatment of sewage, a fair amount of
dissolved material is passed through to the environment with the discharged wastewater. Thus considering the volume
of water discharged to the ocean and the current but unknown suite of metabolic toxins, the impact of this combined
activity can not have a beneficial impact on marine life or the habitat.
There are sufficient technologies extant to allow conversion of this daily sludge out put as a recoverable energy source.
Further, technologies exist to remove the solids ahead of treatment by a POTW. This obviates the bioconversion of
solids such as heavy metals into solutions. As we have noted above, current POTW technology and design are
notoriously poor at dealing with solutions. Thus the negative externalities that now accrue to these activities can be
essentially erased and the sludge (extracted or separated solids) can be converted into a valuable source of renewable
energy. Using the above data, this is equivalent to 12,300,000 cu ft of methane per day.
Based on data supplied by MicroMedia as a rule-of-thumb-equivalent, 600 MGD of wastewater would supply 20,000
homes with their energy needs. Thus, using this conversion, the 4100 tons of sludge would equate to the energy needs
of Santa Barbara and its surroundings. This energy equivalent, is however mainly squandered on land application and
thus evolves into CH4; this consequently converts into 21 times that amount into CO2. Thus, a major and previously little
considered source of greenhouse gas emissions is the land application of sewer sludge.
For example, the Bakersfield area currently receives, from the Greater LA Basin area, roughly ½ million tons of sewer
sludge annually. At 3,000 cu ft of CH4 per ton of sewage sludge, this amounts to 1.5 billion cu ft of CH4 evolving into an
oversubscribed air basin (lower Central Valley) and thus the Bakersfield area and its industry are subsidizing the LA
area’s population and its smog problem.
For example, the wine and grape growing industry of the San Joaquin as well as agriculture generally, are picking up the
cost of this inter-basin translocation of air quality impact. The results of air pollution within the lower San Joaquin is now
also seeing a tax on both the area’s wine industry and building trades industry through an equivalent of a tax applied by
the area’s air pollution district. This is clearly a subsidy for LA’s sludge industry and the land application of sewer
sludge. This observation is but one of the negative aspects of this activity. The cost in human health from smog in the
lower San Joaquin Valley would also need to be entered into the calculations.
Further, the transport of this sludge represents a major cost and use of fuel. The emissions from trucks hauling sludge
between LA and Bakersfield over the Garpevine constitutes a not only a secondary major source of air quality impact,
but represents an unneeded consumption of fuel recourses.
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