Sludge Watch ==> Ventura Calif- Sludge pellets to landfill - what about fire?

[Maureen Reilly]

http://www.venturacountystar.com/vcs/county_news/article/0,1375,VCS_226_5410548,00.html


Bill could prevent hauling of sludge out of the county
Public works officials say local solution is overdue

By Charles Levin, clevin at VenturaCountyStar.com
March 11, 2007

For 10 years, Oxnard trucked its wastewater sludge to a Kern County farm, 
where the sewage-treatment leftovers found new life as fertilizer.

Regulators, however, closed the farm last year over environmental concerns, 
and in June, Kern County voters banned the use of sludge in unincorporated 
areas, worried about potential groundwater contamination.

Oxnard has worked its way around the ban by sending its sludge, also called 
biosolids, to a composting facility in Kern County. However, a new bill by 
state Sen. Dean Florez, D-Shafter, could add more red tape and costs to such 
efforts.

"It's going to be more and more difficult as time goes by to haul biosolids 
to other locations," said Mark Norris, Oxnard's wastewater superintendent.

Oxnard's dilemma underscores the increasing difficulties public agencies 
face in disposing of sludge.

The Ventura Regional Sanitation District is nearing final approval for a 
sludge-conversion facility at its Toland Road Landfill between Santa Paula 
and Fillmore. However, while local public works officials support the 
facility, some contend it won't meet the county's long-term needs. Several 
Toland neighbors also worry about traffic, and dust contaminating nearby 
crops.

Thirty-five years ago, wastewater plants discharged untreated sewage sludge 
into rivers, creeks and the ocean. The Clean Water Act in 1972 forced 
agencies to seek cleaner methods of disposal.

Treated sludge is one result. When not used as fertilizer, it can be 
incinerated or buried in landfills. To use it on crops or as compost, 
disease-causing pathogens must be removed. Ventura County farmers, however, 
won't touch it, concerned about contamination.

The Sanitation District's proposed facility would heat sludge for several 
hours at 212 degrees to remove pathogens and meet the highest federal 
standards. The process would also wring out moisture, which often composes 
up to 85 percent of sludge. The remaining water would be treated at the 
Toland site and again at a wastewater treatment plant, according to Mark 
Lawler, the Sanitation District's general manager.

This would leave small brown pellets to be used as ground cover at the 
landfill. Methane gas already generated by the landfill would power the 
heating driers.

Public works officials countywide say a local solution for sludge disposal 
is long overdue. Several agencies, such as the cities of Oxnard, Thousand 
Oaks and Ventura, truck their biosolids out of the county for composting. 
Simi Valley sends its sludge to its landfill.

Converting it to ground cover at Toland would reduce the amount of waste 
sent to landfills, lower transportation costs and reduce garbage truck 
emissions.

"It's a brilliant concept, and it's going to save Fillmore residents a lot 
of money in the long run," said Bert Rapp, the city's public works director.

The Sanitation District would charge local agencies to use the facility, 
Lawler said. He declined to discuss fees but said most have agreed to use 
it.

Oxnard processes 79 tons of sludge a day — including wastewater biosolids 
from Port Hueneme — making it the county's largest producer, according to a 
recent Sanitation District analysis.

Transporting it to Toland could cost from $8 to $10 a ton, Norris said. 
Shipping costs to Kern County were not available, but if the city had to 
seek another outlet, such as Arizona, transportation could cost $40 a ton, 
Norris said.

Sludge production rising

Reddy Pakala, Ventura County's wastewater superintendent, supports the 
proposal but isn't certain the facility can meet long-term needs as the 
county's population swells.

Sludge production in Ventura County is expected to reach 302 tons a day by 
2020, according to a 2005 analysis by the Sanitation District. Currently, 
the county produces 280 tons a day, according to the latest figures.

"What they're doing is a good first step," said Pakala, whose agency offers 
wastewater treatment services for Piru and Moorpark. "But I don't think it's 
a holistic solution for Ventura County."

Pakala hopes to meet soon with public works officials to discuss other 
options. Alternatives include burning sludge to provide energy or mixing it 
with other materials for use as construction material, said Lauren Fondahl, 
a biosolids coordinator with the federal Environmental Protection Agency.

"We would love to find a commercial reuse for this," Lawler said of the 
county's sludge. "We just don't have one at the moment."

However, he's confident the Toland facility can handle all the county's 
sludge.

Traffic, pollution concerns

Despite a report that says the Toland project won't harm the environment, 
some neighbors are worried. Trucks enter the dump via Toland Road, right off 
Highway 126 near Santa Clara School. However, trucks on eastbound 126 have 
no left-turn lane onto Toland, said Katie Brokaw, the school site president.

The Sanitation District forbids truck deliveries from 8 to 8:30 a.m. and 2 
to 2:30 p.m. — when parents drop off and pick up kids at the school — but 
some trucks still come through, Brokaw said. With sludge as an additional 
commodity, Brokaw expects more traffic and violations.

"It's a recipe for disaster right there at that clinch point," Brokaw said.

Lawler said the Sanitation District has monitored the intersection since 
hearing complaints but found no violations.

Gordon Kimball, a Camarillo resident who farms 100 acres of avocados about a 
mile west of the landfill, contends a sludge facility belongs at a sewage 
treatment plant, not in an agricultural valley.

"My greatest fear is that we have avocados that end up making people sick, 
and we can't figure out why," Kimball said, raising concerns about dust 
contamination.

Edo McGowan, a retired water quality scientist for Ventura County, said the 
federal government's standards for treating pathogens are weak. In a strong 
rain, pathogens could percolate into groundwater aquifers, reaching drinking 
supplies and the food chain, said McGowan of Ventura.

Maureen Reilly, director of the Ontario, Canada-based watchdog group Sludge 
Watch, said treated pellets and dust can ignite from spontaneous combustion 
if not stored properly. Reilly cited several incidents in Toronto and New 
York City.

Lawler disagreed, saying the Toland facility would meet the Ventura County 
Air Pollution Control District's highest standards for dust control, and 
that heating sludge for several hours as planned would sterilize it and 
destroy pathogens.

Approval likely

The Sanitation District wants to modify its conditional use permit for the 
landfill to allow the sludge facility, which requires a decision by the 
county's planning manager but not the Planning Commission. Approval is 
likely, said Scott Ellison, a senior planner with Ventura County. Opponents 
can appeal to the Planning Commission or Board of Supervisors, Ellison said.

Kimball said he would likely appeal an approval.

Meanwhile, Kern County's ban on sludge is on hold. In November, a federal 
judge ruled the June initiative discriminated against Los Angeles-based 
sanitation districts, undermined the state's recycling law and exceeded the 
county's regulatory powers. The case is now on appeal.

Florez's new bill, SB55, would require wastewater agencies to guarantee the 
quality of sludge and assume financial responsibility for problems caused by 
its disposal.

It would also order local agencies to certify that sludge meets and possibly 
exceeds federal standards.

"You have to stand behind your product and take the liability if something 
goes wrong with it," Florez said.

Oxnard sewage official Norris said he believes the bill duplicates existing 
regulations and just makes it more onerous for local government.

Meanwhile, sludge production will increase as population grows, Norris said. 
"It's not going away."


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The article below was published by the Ontario Fire Marshall's Office in
the Publication:
Ontario Fire Service Messenger November/December 2002

................................



Sewage sludge pellets: fire and explosion risks

There are rabbit food pellets, pellets for guns, wood pellets for
burning in stoves, and there are even sewage sludge pellets! What will
they think of next?

Introduction
Sewage sludge is the nutrient-rich organic byproduct of the wastewater
treatment process. It contains most of the nutrients required for crop
growth, and organic matter, which can enrich soil, and may also be
called “biosolids”.
For some people, spreading biosolids on farmlands is considered to be
perfectly safe way of returning nutrients to the ground if appropriate
procedures are in place. Recycling this nutrient source is viewed to be
better than putting it in a landfill site or incinerating it.
Other people believe that cities are simply transferring urban pollution
to the countryside, and site concerns about the fumes, respiratory
infections and other negative health effects that may stem from exposure
to biosolids, and the potential for contaminated well water and water
courses.
Sewage sludge can exist in liquid forms and can also be converted into
granules or pellets by removing the moisture. In this solid form,
pellets are easier to handle and store, and transportation costs are
reduced, as compared to liquid sludge.
Although people may be aware of the environment aspects associated with
the disposal of sewage sludge, they may not be aware that sewage sludge
pellets have been associated with numerous fires and explosions. For
instance,

- Sludge pellets stockpiled at a farm in Windsor caused a smoldering
fire.
- There were a series of explosions in a Windsor pelletization plant,
most recently in October 2002.
- The City of Toronto had problems with the self-heating of sewage
pellets in a storage silo.
- An explosion at the Miloganite plant in Milwaukee in 1996 caused
serious injuries to a worker and $ 4.5 million worth of damage to the
plant and property.

This article has been prepared to provide information on potential fire
hazards associated with sludge pellets, safe storage and effective fire
suppression.

Self-heating properties of the product:
Sewage sludge is mainly derived from human waste, but may also contain
animal products, paper, high fat content from processing plants, heavy
metals, organic contaminants and petroleum products from petroleum and
diesel spills. When formed into pellets, the finished product has less
than 5% moisture content.
Should the moisture content of this material reach between 5- 10% by
weight of the product, aerobic biological decomposition occurs, causing
self-heating. Water generated by this process is absorbed by the
surrounding sludge, which intensifies the self-heating process. A
smoldering fire may occur if the heat generated by this self-heating
process is not dissipated to the surroundings.

Processing and Handling
In the initial stages of sewage treatment, the digestion process
produces methane and carbon dioxide. If raw sludge is stored it will
decompose and produce hydrogen sulphide and other volatile sulpher
compounds. With the addition of chemicals to dewater the sludge,
hydrogen sulphide and ammonia may be released.
Conversion of sewage sludge into granules or pellets, by removing the
moisture, is the final stage of the sewage treatment process.
The amount of dust produced in the drying process and later processing
is affected by the method of drying and type of final product. Sewage
sludge dust is about the same size and similar hazard as wood dust.
Depending on the design of the plant, there is the potential for a dust
explosion to occur at the main dryer, dust collector and handling plant,
pelletizer and final product discharge plant.
In pellet form the product is sufficiently hard to withstand the normal
conditions of mixing, handling and transportation without producing
excessive levels of dust.
These pellets have a relatively low auto-ignition temperature, as low as
2650C, and may be easily ignited without process precautions.
A risk assessment followed by implementation of suitable prevention and
protection measures is required for all parts of the process. Special
attention should be given to the specific hazards associated with the
generation of methane, hydrogen suphide, and dusts. Appropriate
ventilation, relief venting, suppression systems, containment features,
avoidance of ignition sources, and safe handling and storage practices
also need to be considered.

Storage
Once dried, pellets may self-heat to the point of ignition and slow
burn. To minimize the potential for self-heating, sewage sludge pellets
should be kept cool and dry and should not be stored in large piles.
Storage silos should be designed to aid cooling and be sized to allow
thermal dissipation of heat. For this reason, tall narrow silos are
preferable to wide silos. Where significant levels of dust are likely to
be produced in the storage silos, they should be designed to mitigate
the effect of any explosion. The simplest protection is the provision of
explosion relief panels venting to a safe location.
Silos should be designed to identify and contain a fire. A slow burning
silo fire is likely to be starved of oxygen and therefore produce carbon
monoxide. A carbon monoxide detector in the silo will indicate an
incipient fire. As well, multi-point temperature probes may be installed
to monitor the temperature of the product. As an alternative to indoor
storage, pellets should be transported to a site location and be
off-loaded and turned into the soil as soon as possible.
If this is not possible, the material should be spread on the ground
evenly in the form of a very thin layer. This configuration will
dissipate any heat generated into the ground and atmosphere.


Fire suppression
Inside a silo, an inert gas can be used to contain, but not necessarily
extinguish, a fire. The injection of an inert gas will cause a drop in
temperature, but may only have a limited effect. The temperatures should
be monitored for several hours before deciding if the fire has been
controlled. Procedures to deal with a silo fire may include the gradual
emptying of the silo to a safe location.
Outside, a sewage sludge pellet fire typically smolders at the surface
with a relatively low burning temperature and emits dense white smoke
and products of incomplete combustion. The smoke may contain organic
acids and other compounds that are irritating agents. The simplest way
to deal with such a fire is to dissipate the heat by spreading out the
pellets. It may also be extinguished by confining and smothering.
Alternately, the pellets may be mixed into the soil or “stamped” with
heavy earth moving equipment.
In some cases, the use of Class A foam may be considered for fire
suppression. Class A foam is a special formulation of hydrocarbon
surfactants, that reduces the surface tension of water and provides for
better water penetration and increased effectiveness. Class A foam acts
as a surface barrier to stop or prevent further combustion.
The use of water to suppress this type of fire is controversial. The
application of water may actually support a fire by contributing to the
process of aerobic decomposition. Further, adding water may return the
dried sewage into liquid sewage and create additional leachate and
runoff. In turn, this may contaminate ground and surface waters
surrounding the site and could cause significant environmental and
health risks.
Overall, fire fighting tactics need to consider a range of
circumstances, not the least of which include the size of fire,
location, wind/weather conditions, water supply, personnel safety,
access to heavy equipment, and environmental impact.

Conclusions
Although fires involving sludge pellets are not common occurrences, they
do tend to attract a great deal of public attention and challenge the
fire service.
By working with the public, pellet factory owners, and owners of sites
used to spread sewage sludge pellets, the fire service can ensure that
safe practices are employed, thereby protecting the public, environment
and emergency responders.

Article prepared by OFM Fire Protection Engineers Beth Tate and Miles
Mailvaganam.