What Is Leachate? And How Is It Collected From The Bottom Of A Landfill?

Rainfall enters the landfill cell, and what isn't absorbed into the waste moves down to the basal filter. It passes through the pipe network, and rests in the sump. Pumps remove it from the sump, and may have to lift it 30 to 80 metres upward out of the top of the landfill. Make no mistake about how difficult this is. Even with modern pump technology to help, it is no easy feat to achieve this in the demanding conditions deep inside a landfill.

Leachate collection systems must be planned. The number, location, and size of the sumps are vital to an efficient operation of the landfill.

When designing sumps, the amount of leachate and liquid expected is the foremost concern. Areas in which rainfall is higher than average typically have larger sumps. This is called leachate management.

Leachate Management

A further criterion for leachate management sump planning is accounting for the pump capacity. The relationship of pump capacity and sump size is inversed. If the pump capacity is low, the volume of the sump should be larger than average. It is critical for the volume of the sump to be able to store the expected leachate between pumping cycles.

This relationship helps maintain a healthy operation. Sump pumps can function with preset phase times. If the flow is not predictable, a predetermined leachate height level can automatically switch the system on. Other conditions for sump planning are maintenance and pump drawdown.

Leachate Collection

Collection pipes typically convey the leachate by gravity to one or more sumps, depending upon the size of the area drained. Leachate collected in the sump is removed by pumping to a vehicle, to a holding facility for subsequent vehicle pickup, or to an on-site treatment facility.

Sump dimensions are governed by the amount of leachate to be stored, pump capacity, and minimum pump drawdown. The volume of the sump must be sufficient of hold the maximum amount of leachate anticipated between pump cycles, plus an additional volume equal to the minimum pump drawdown volume.

Sump size should also consider dimensional requirements for conducting maintenance and inspection activities. Sump pumps may operate with preset cycling times or, if leachate flow is less predictable, the pump may be automatically switched on when the leachate reaches a predetermined level.

Leachate Pipes

The leachate pipes should allow all the leachate to be pumped away, where it can be treated and the resultant slurry reintroduced either to the same landfill or sent to another. However, they can easily become clogged either by precipitation caused by chemical reactions due to the composition of the material that's in the landfill, or from a build-up of micro-organisms in the pipes, or due to the fact that unless designed correctly by experts the pipe walls may be crushed under the many thousands of tonnes of rubbish piled on top of them.

Summary

In the narrow environmental context leachate is therefore any liquid material that drains from land or stockpiled material and contains significantly elevated concentrations of undesirable organic and inorganic material derived from the material that it has passed through.


To prevent it building up inside landfills and escaping from the landfill liner, it has to be lifted out through  leachate collection system deep inside every modern landfill, using very robustly made pumps. This is an often costly challenge for pump manufacturers and landfill engineers alike, but the land around landfills and frequently also the drinking water supplies of the local people, depend upon this being done effectively both now, and for very many years into the future.

Find out more at the Leachate Website - www.leachate.co.uk.

Leachate from Waste and What Dribbles From Many Garbage Collection RCVs

Leachate Keeps on Getting a Bad Press!

A leachate soakaway lagoon excavated on the top of a
landfill to avoid leachate escapes from the
landfill perimeter, in the summer after heavy winter rain.

Leachate isn't that hard to handle when the right level of expertise is applied, but it does cost a fair amount of money, and leachate managers need to take care to provide constant vigilant, and mindful attention to leachate flow rates, especially to ensure that the site operator adequately controls rising rates of leachate production due to periods of wet weather.

Leachate spilt during collection from premises during wet weather is a big factor in high rainfall countries and regions such as around Kuala Lumpur in Malaysia, and it really does need collection in tanks beneath the refuse collection vehicles. But, the collection service operator then also often has to treat the leachate once it is brought back to the waste depot, and that may be harder to achieve than collecting it in tank below the bodies of the refuse collection vehicles in the first place.

Also, many landfill operators have been caught out when, after wet weather, landfill leachate flows can rise from previously created leachate just when least expected, and this can be several months after the rainfall that caused it to be produced has had time to percolate down, and out of the waste again, under gravity. in our second article the authority responsible seems to have set up good contingency haulage plans if case of high future wet weather leachate flows.

The extracts form the two articles which follow, have been selected to illustrate the points we make above.

ᔥLeachate leaves a stinking trail - New Straits Times:

FOUL SMELL: Residents in Kepong are complaining about the stench left behind by the garbage compactors servicing their areas

KUALA LUMPUR: THE problem of leachate leaking onto the streets as garbage compactors move around to collect rubbish is a common occurrence in many neighborhoods despite an instruction from a former Alam Flora   chief executive officer a decade ago to install buckets on the trucks to stop spillage.  It is raising the ire of residents.

Two locations checked by Streets had the same problem.

Taman Kepong resident Sue Ng said that every morning when the Alam Flora truck turns up behind Restoran Lima Bintang, it leaves a trail of leachate on the road.

"The stench is unbearable," she said. "At the same time, the restaurant workers have refused to wash down the leachate from their garbage, despite being asked to."

"The contractors should either given a stern warning or have their contracts cancelled," [resident, Jack Tan] said.

ᔥThe county signs contract for stinky liquid overflow - The News Herald

The harder the rain, the bigger the leachate load.

Heavy precipitation means more water runs through the county landfill, slipping and sliding through the refuse, eventually draining out as a clear, stinky liquid called leachate. And Bay County must haul the end product to a treatment facility at Panama City Beach.

Big rains mean the county needs a back-up hauler and now a New Jersey company will help out. The County Commission recently approved a contract with Dana Transport Inc., which has a Panama City office. It was the low-bidder, offering $23.50 per 1,000 gallons hauled. The second-place bidder offered $60 per 1,000 gallons.

“It’s really a contract to supplement our efforts,” said Glenn Ogborn, the county’s solid waste superintendent.

The amount of leachate hauled per year varies by rainfall. In fiscal year 2012, the county moved 5.8 million gallons from the Steelfield Road Landfill, but in 1999, it carried 14.7 million gallons, due to major storms, Ogborn said.

We hope that you found this article interesting, and that you will give us the benefits of your thoughts on this subject by adding your comments in the box provided for that (usually to be seen below the video.

Leachate Treatment Plant Design

Leachate Treatment Plant Design strategies can vary quite considerably because the individual requirements for leachate treatment on each landfill site varies site by site, and through the life of each site. The starting point for any Leachate Treatment Plant Design is always to establish the strengths, composition and volumes of leachate and predict those into the future at least for the initial design life of the leachate treatment facility proposed. The expert skills available from the Leachate Expert website www.leachate.co.uk can assist you in the specification, design, build, installation and commissioning of the most appropriate solution for your site. Within our expertize is also the operation and maintenance of the plants designed by the "Leachate Expert".

Process Design and Implementation - Based on a minimum of information we will work with our clients to provide a practical and economical process design which will then form the foundation of the project. Each project engagement can range from providing feasibility studies, design layouts and process flows, project management, specification, HAZOP’s, P&ID’s, landfill products and plant support.

Leachate Treatment Plant Design is evolving, and will continue to do so as modifications in landfill practices continually add the higher polluting risk arising from sanitary landfill leachates at many landfill sites. Historically, and up and until the early 1970′s, sites for the disposal of domestic wastes were normally small and provided for local waste disposal needs only, each serving a fairly minimal geographical area. Controls applied by regulatory authorities were very basic. These sites were also characterized by reduced input rates, high ash content of wastes from open fires and at the site, combined with the low densities of uncovered wastes which allowed all the waste to continue to gain access to air, and offered a level of negative environmental effects that were typically only locally felt and restricted in severity.

How Does a Modern Landfill Work?

In those days there was little or no Leachate Treatment Plant Design, because smoke, flies and vermin, combined with iron-staining and developments of fungi and micro-organisms in neighborhood streams, were generally tolerated as the acceptable cost of waste disposal. However, everything has changed now, and in most nations the savings from disposal of domestic wastes in what were no more than un-engineered and largely un-controlled “dumps” or “tips”, are considered not worth the environmental damage they do.

Now Leachate Treatment Plant Design is a specialist and highly technically sophisticated subject due to the high strength of modern leachate, and in most countries (unless pre-sorting removes a high proportion of putrescible waste) there is still a a continual increase in wastewater strength. Also, in recent months the volume of wastewater generated at many landfills, due to a wet winter, has exceeded the treatment capacity, resulting in an increase in wastewater being hauled to off-site disposal. To eliminate hauling, and meet more stringent discharge standards from the local POTW a new or revised Leachate Treatment Plant Design may be needed.

The Leachate Expert at www.leachate.co.uk is involved in the evaluation through design and construction of new and better (lower cost) leachate treatment plants. Initially, The Leachate Expert will evaluated plant flow and wastewater quality data to determine the required capacity. The Leachate Expert then prepares a management plan to address the different scenarios available to the site for leachate wastewater disposal. These scenarios investigated usually include: (1) pretreatment and discharge to either a public sewer, (2) or the landfill (i.e., recirculation), (3) complete treatment and reuse on site; and complete treatment and watercourse discharge.

Back to Basics in Landfill Leachate Treatment

Landfill leachate is generated from liquids existing in the waste as it enters a landfill or from rainwater that passes through the waste within the facility. The leachate consists of different organic and inorganic compounds that may be either dissolved or suspended. An essential part of maintaining any landfill is managing the leachate through proper treatment methods designed to prevent pollution into surrounding ground and surface waters. Even when a landfill is located in an arid area, leachate may be produced during wet weather periods, and its consideration remains necessary, although management may be by evaporation in many cases.

If leachates have a distinguishing characteristic, it is that flows are variable. Flows change according to the weather. The highest leachate generation will occur after rainy periods, decreasing during dry and when the leachate from previous events ceases to percolate through the waste and appear at the base of the landfill. Therefore, waste concentrations can change dramatically according to the weather conditions and as the waste matures over the life of the landfill. It follows that, no landfill leachate is constant over time, and no two leachates are the same. However, large landfills operated according to the EU landfill directive with less than 50% recycling taking place before it reaches the waste are remarkably similar when age of waste and leachate is taken into account.

Landfill Leachate Treatment Strategies

Landfill leachate treatment strategies can vary quite considerably subject to the individual challenges on each site as well as relative strengths, composition and volumes of leachate. The experts at the "Leachate Expert website" (see www.leachate.co.uk ) have designed dozens of successful leachate treatment facilities over the last 25 years, and can assist you in the specification, design, build, installation & commissioning of the most appropriate solution for your site. Naturally, we can thereafter provide operation and maintenance services.

Based on a minimum of information the leachate experts work with their clients to provide a practical and economical process design which will then form the foundation of the project. Each project consultancy involvement can range from providing feasibility studies, design layouts and process flows, to project management, specification, construction procurement, landfill product selection, HAZOPs, P&IDs, etc, and plant operational support.

A very wide range of treatment processes have been applied to leachate treatment with varying success. The processes which have been consistently successfully applied, for municipal waste landfill leachate from controlled landfills, are biological processes designed by specialist leachate process designers.

In many countries standard national discharge consents limit the applicability of biological processes due to their high stringency of the purity requirements, and removal of salts. Thus can be the result of consents which are designed for simplicity as national standards, and which adopt a requirement that all discharges must meet a high quality standard suitable for all cases.

Regulators often suggest that leachate should be pumped to a sewer for treatment at a urban Wastewater Treatment Plant (WWTP). However, this may historically have been driven by concerns that leachate treatment on site is challenging and difficult to achieve reliably, than by a detailed appraisal of the best options available. This however is no longer true, especially for designs from experienced specialist LTP designers, such as those at the "Leachate Expert website".

Is Leachate Treatment at Any Sewage Works A Good Idea Environmentally?

In reality it is not usually a good policy to treat strong leachate from modern sanitary landfills after discharging it into sewer. The act of mixing it with sewage makes it more difficult to treat by sewage treatment plants. Sewage works are not designed for such high ammonia effluents. Leachate has an extremely high ammoniacal nitrogen ("ammonia”) concentration when compared with the much weaker contamination levels in domestic, commercial, and industrial foul sewage.

This is why treating strong leachate at a Wastewater Treatment Plant, as if it were sewage, is  not efficient and leads to unnecessarily cost. Unless the WWTP has a high efficiency nitrifying process set-up already ammonia removal may be very poor. The result is that ammonia, which is one of the most potentially damaging types of contaminants in leachate, may simply be being diluted by its addition to sewage which is much weaker in ammonia, and the WWT may comply with its discharge consent by dilution, and even not treat the ammonia.

What Every Leachate Treatment Engineer Should Know About Contracts

O.K.! In our headline we have to admit that we changed the title to add in "Leachate Treatment", and the course we are recommending here is a general course, aimed at all engineers. However, the IChemE Forms of Contract are particularly useful for those like Leachate Treatment Engineers and Managers, who need a form of contract which is designed for a process plant.

The ICE offers similar courses, but for a leachate treatment plant contracts they are not nearly as good, because they are all about getting a structure built, and nothing much beyond that.

Process Plants are different. A bridge is finished and providing value as soon as the red-tape is cut, and the road over it, is opened. 

A process plant is different. To have a process plant built and sitting there is no good to anyone. A process plant like a leachate treatment plant, has to be commissioned, and working to produce the treated effluent to the quality specified by the discharge consent.

There are IChemE Forms of Contract for process plant contracts which suit every type of financing as well, so attending this course is really important for those in the leachate treatment industry, and if you are active in this area, we recommend attendance.

The details of the course follow:

The "What Every Engineer Should Know About Contracts" course will provide you with a
detailed understanding of contract law as it relates to engineering and construction contracts. It is taking place twice in the UK this year: 1-2 May in Rugby and 15-16 October in London.

Suitable for engineers of all disciplines, the course examines the law of contract and of tort within which engineering and construction contracts are made and operate.

It also looks at:

• the structure and essential contents of these contracts risk allocation and its links with payments
• the role of the contract administrator why the various standard forms of contract say what they say 

It is ideal for managers involved with contracts, particularly those who have moved into a procurement, project or contract management role, as well as engineers who are developing their skills across the range of business activities.

Click here for full course details and to register

Download the course brochure

You may also be interested in: 

IChemE Forms of Contract

12-13 June 2013, Redcar, UK
19-20 June 2013, London, UK

Helping those who will prepare, tender or manage a contract using the IChemE forms to understand their structure, main provisions and features, and the key differences between them. Fully updated to cover the new 2013 suite of UK contracts. Find out more here.

Please note that this is not a sponsored recommendation. We make no money from the course promoter if you attend.

What Is A Membrane Bioreactor?

So you desire to understand what this really is? You would be surprised how often individuals inquire about that question by seeking the world wide web. That's the reason we now have composed this article to describe what family or friends will feel you unaware or even ridiculous for inquiring the things they might think would have been a foolish issue.

In principle, a membrane bioreactor combines biological treatment with a separation process using microfiltration membranes. An advantage of the net is that you can ask these queries about just about any topic, and always with no stress that your buddies think of what you ought really to already know about!

So, I want to now get on with answering your problem by what a membrane bioreactor or "MBR" really is.

It is a sophisticated water treatment system commonly used for strong organic effluent treatment as in for example the aerobic treatment of landfill leachate.

First, a Membrane Bioreactor consists of a reactor tank and a microfiltration unit, which can be defined as: the use of membranes to allow the almost complete elimination of suspended solids from the effluent, with the conservation of all bacteria in the reactor while also removing BOD and COD and ammoniacal nitrogen concentration which is largely converted to the nitrate form in solution.

To make that clearer, here is a list of instances in which a membrane bioreactor might be used, as follows:

• It is also an MBR when referred to by many people, and also some will include an 
• MBR in a Reverse Osmosis Plant when treating landfill leachate.

So let's attempt to simplify items.

These can be classified into the following types of MBR Plant,as follows:

• MBR with Reverse Osmosis, 
• MBR with Activated Carbon, 
• MBR with Nanofiltration etc.

The main of those is:

MBR with Reverse Osmosis

Their unique characteristic is the fact that in the reactor, the micro-organisms which are mostly bacteria transform dissolved polluted matter into biomass, and NH4 nitrogen (“ammonia”) into nitrate. In this way biodegradable organic contaminants are eliminated by the bioreactor as well as a number of metals which are oxidized into mostly insoluble compounds. The suspended solids are then eliminated from the flow by the microfiltration membrane.

The key issue, to consider about membrane filtration, is that it allows the retention of non-soluble molecules having a high molecular weight and in that way increases their residence/retention time and also as a result increases the extent to which of biodegradation occurs inside the biological reactor (bioreactor).

Now that you have see this article you should know far more about the use of membrane bioreactors or "MBRs" for leachate treatment, and this will, we hope have made it easier for, you. 

Using this method of this research you have applied the services of the net intelligently to answer a really distinct query which can be important to you at this time resolve. 

Now reader, you can instantly compliment yourself for your learning and by educating yourself, most of us need to obtain increased good results in your lifestyles, so we surely think that you're going to experience that as well

Uncover how you can use the MBR with Reverse Osmosis treatment system by visiting the membrane bioeractors page on the website at leachate.co.uk/main/leachate-treatment/how-a-membrane-bioreactor-is-used-to-treat-landfill-leachate/.

Answers to Current Questions Being Asked About Leachate Treatment

We have compiled a list of the most common questions being asked at the moment about leachate treatment and leachate management for landfill sites. Top of the list of these are:

1. What Is Leachate?
2. What Is A Leachate Attenuation Zone?
3. How To Calculate Leachate Generation?
4. What Are Leachate?
5. What Causes Leachate?

These are all questions which are answered at our main web site at www.leachate.co.uk .

However, to assist our readers I will provide quick answers below:

1.What Is Leachate?

Leachate is the contaminated liquid which runs out of another material, in our case we are talking about landfill leachate, and the dirty water that accumulates in, or runs out of the bottom of, landfill sites.

2. What Is A Leachate Attenuation Zone?

A Leachate Attenuation Zone is a soil material which is only partially permeable through which leachate flows (usually by gravity) and as it flows through slowly it becomes less contaminated ("cleaner"). The reduction in contamination can take place by biological action or by physico-chemical action.

3. How To Calculate Leachate Generation?

This can be difficult and there are several sophisticated water balance modelling softwares which will attempt to do this for you. The problem with using them is in understanding how they work and whether you can trust them to give the right answer. I usually carry out a water balance using  a spreadsheet, on an annualized basis. Contact me if you need assistance with a water balance problem for a landfill at http://ipptsassociates.co.uk/contact/  .

4. What Are Leachate?

Although this comes up as a question a lot online, it is grammatically incorrect and makes no real sense. See answer 1. above.

5. What Causes Leachate?

In modern landfills which do not accept liquids for disposal, it is mostly the organic matter (food scraps, grass mowings etc) which are in a municipal waste landfill which decay to form leachate. During decay, the cells of the organic material rupture and the contents of the cells dissolves in rainfall trickling through the leachate producing a smelly, and quite often black liquid which over time (if left in the landfill) usually turns into an amber liquid which often smells of ammonia, but may just smell "earthy".

For more information about commonly asked leachate questions visit our website at the leachate expert  .

Toxic Waste Disposal and Landfill Gas Risks from Sandy Superstorm Aftermath

Those responsible for toxic waste disposal are working alongside the other public bodies to clear up the damage from the recent Sandy Superstorm (hurricane) in the eastern states of the US at the end of October 2012.

An urgent issue is the collection and safe disposal of many paint, oil and other miscellaneous drums of material which has been washed out of properties during the storm surge in areas such as Long Beach.

Steve Last also highlights the risk of unexpected landfill gas emerging from previously dormant abandoned landfills which may now have become wetted where they were previously dry and starting to produce methane again even for the first time.

Those that read this blog would not be wrong to suggest that at the same time there may be leachate problems if the waste has been flooded and then produces leachate.

See the full article at the following link:
Toxic Waste Disposal and Landfill Gas Issues in Sandy Superstorm Aftermath

Sanitary Landfill and Leachate

I was blogging recently about sanitary landfill leachate when from a reader's query it became clear that they were not clear about what a sanitary landfill comprises. In this article I set out to put that right.

Migration Hazards at a Sanitary Landfill (Image: Masterplan
for the Aftercare of Abandoned Landfills, Van Vossen, Gravesteijn,
Kasma  and Vos; proceedings Sardinia 95, 5th Sardinia Landfill
Symposium Cagliari, Italy)

The standard definition of a Class III or "Sanitary Landfill" originates in North America and the term has spread around the world from that source. It is, as defined in the US, a landfill that accepts household garbage and is normally lined below to reduce the escape of leachate to an environmentally acceptable rate, operated to minimize leachate generation and keep the waste as dry as possible, and capped as each area of the landfill is completed - again to keep leachate to a minimum but also to allow efficient collection of the landfill gas the landfill produces. The best sanitary landfills also have a recycling center at the site or the waste passes through a recycling center before it reaches the sanitary landfill. The recycling center these days often includes processing which separate waste types and process the waste, and comprehensive centers where waste is reduced, recycled and reused are called MRFs, and some are also known as MBT Plants.

The modern sanitary landfill is lined in the US with multiple layers to protect soils and the water bearing aquifers underneath. The in the US liner is composed of multiple natural layers and an impenetrable plastic (HDPE) or similar material. The purpose of the liner is to hold the waste for as long as possible collect all the "garbage polluted rainwater" (known as leachate) so that it can be extracted and treated. In Europe and worldwide the plastic lining is usually a single layer of thicker material than is usual in the US.

The new environmental centers being built for many sanitary landfills offer the opportunity for the community to become a more sustainable community. It will not only enhance the area's management of its waste but will also provide state-of-the-art and innovative recycling and in many cases the production of renewable energy.

Sanitary Landfills in More Detail

In short sanitary landfill is simply a general description of a type of landfill, it is the commonly accepted method of controlled disposal of municipal solid waste (refuse) on land in most countries. The method was first used in England from 1912 (where it has was then called controlled tipping, and is now called controlled landfilling). Waste is deposited in thin layers (up to 1 metre, or 3 feet deep) and within hours compacted by heavy compaction machinery (known as "compactors" these are similar to bulldozers but instead of having tracks have steel cutting wheels to break up the waste). Several layers of waste are placed and compacted on top of each other over a period of a day to several days, to form a refuse cell (up to 3 metres, or 10 feet, thick).

At the end of each day the compacted refuse cell is covered with a layer of soil material (or similar) to prevent odor, keep rats out of the waste, and prevent windblown litter from being blown of the site. All modern landfill site locations are carefully selected and prepared before the waste is placed. They are sealed with impermeable synthetic bottom liners to prevent pollution of groundwater from leachate or other environmental problems.

When the landfill is completed, it is capped with a layer of low permeability material such as a clay, or a synthetic liner, in order to prevent as much water as possible from entering. A final topsoil cover is placed, compacted, and landscaped, with various forms of vegetation being planted to reclaim the surface for the planner after-use.

Traditional landfills, before sanitary landfills were introduced were referred to as “open” or “polluting” dumps, simply containing un-engineered sites with waste under the ground. Such sites potentially allow the waste by-product called leachate to enter and contaminate groundwater and other water sources. They also attract rodents, insects and other disease-carrying vermin. Other negative effects of open dumps include emission of air pollution, odors and the creation of potential fire hazards. In a sanitary landfill these risks are partly eliminated, or at least deferred thanks in part to protective liners and monitoring systems that ensure there is no harm done to the environment, for just as long as the leachate is removed and treated.

What is a Leachate Attenuation Zone?

A leachate attenuation zone is basically a buffer zone around a land fill that protects against contamination of groundwater by its pollution from harmful or dangerous wastes. Tons of older landfills were established prior to stricter laws were carried out have been described as having "leachate attenuation zones".

In the UK these sorts of landfills which were most typical before about 1990, were blamed for leachate escapes into groundwater made use of for consuming water abstraction, and came to be called not the safe "dilute, [attenuate] and disperse" landfills their designers meant, but just merely "dilute and pollute" landfills! Sadly, there was much truth in such a description, in numerous cases.

Leachate attenuation zones are, in additional words, locations of the ground around and below those land fills which don't have low leaks in the structure linings, in which leachate seeps out and, biological action, in exactly what are called the "unsaturated" or "aerated / aerobic" zone outside the landfill in permeable ground, lowers the polluting capacity of the leachate by actually treating it.

It the right types of geology with the correct amount of leaks in the structure and ground types these attenuation zones could be very effective and supplied free of charge leachate treat. Unfortunately, unless these leachate attenuation zones are effectively designed by engineers, hydrologists, and hydro-geological researchers, they rarely work well when they happen by opportunity. Nonetheless, they can be created into brand-new unlined landfills if the ground around the land fills and water levels in the ground and flux of circulation through the ground is appropriate. The path size within the attenuation medium and rate of circulation is additionally essential.

Landfills are the most substantially utilized technique for the disposal of solid waste around the world. When water from rainstorms or melting snow percolates with the decaying natural and inorganic waste of these landfills, it comes to be polluted. All land fills produce this kind of contamination, additionally leachate is still produced from landfills that have actually been closed and deserted for years.

Normally, one volume of landfill waste produces between 50 and 100 gallons of a very tainted wastewater called leachate.

Land fills are different from additional groundwater contamination sources due to the fact that after wastes are buried, a series of physical, chemical and biological feedbacks happen that intensify the toxic concentration of the waste that runs off as leachate. In unheard of circumstances, entire new mixes are produced.

The usual leachate from a landfill has high concentrations of ammoniacal nitrogen and sensibly high recalcitrant combinations, that could sometimes additionally include halogenated hydrocarbons such as carbon tetrachloride and methylene chloride, and intricate polymers, plus heavy metals that are not degradable.

Of these toxic contaminants, the conversion of the natural nitrogen in living cells, into ammoniacal nitrogen produces what is not just a long-lived hazardous liquid, but also a liquid which is additionally highly damaging to most aquatic species.

To minimize the problem developed by the development of a leachate attenuation zone, or a plume of contamination in the ground, government organizations might purchase residential property nearby to a landfill to establish a leachate attenuation zone. This is a way of ensuring that no wells or boreholes are built within the zone, which if they were present would certainly deliver contaminated and undrinkable water.

Seymour Landfill Operator Applauded for Applying for Permission to Put Slopes on Plateau

The top of every landfill should be rounded, and certainly never a flat plateau, and if your landfill has a flat plateau you should go right now to the regulators and the planners and ask for more capacity to be allowed to ask for a rounded contour with surface slopes initially at no shallower than 1 in 20, whcih after settlement will end up probably at only 1 in 20 which is only just enough to stop sighnificant ponding. In essence you need the surface water from a landfill cap to flo off it quickly. UK research in the 1990s showed this need for a good shedding slope to the top of a landfill to reduce leachate production, to be a big factor in all cases studied.




Here is an extract from the original article:

TRENT HILLS -- The key to a landfill achieving its full potential is that it be well-rounded. Northumberland County will be making that argument when it applies to the Ministry of the Environment to increase the capacity of the Seymour landfill by 39,000 cubic metres so the mound atop the waste disposal site will be rounded.

The landfill's approved final contours is for a plateau on top which will lead to increased infiltration of precipitation into the landfill and cause "higher than necessary leachate generation rates," manager of planning and technical support Adam McCue said in a report to County council April 18.

If the ministry agrees to the request for additional waste material and cover soil, Seymour Landfill's operating life would be extended by up to two years, he said.

With its capacity currently valued at $95 per tonne, the landfill would produce an additional $1.85 million in revenue during that time, he added.

Mo Pannu, director of transportation and waste management, said the site's capacity is expected to run out by the end of this year or early in 2013.

He said it will take four to five months for the application to be processed.

The application to the ministry will cost $22,700. The County also approved an expenditure of $42,500 to develop detailed design, operations and closure plan in support of the request. Both expenses will be funded from savings in this year's transportation and waste management department budgets.

View the original article here

General Electric Company and SI Group Inc. Awarded EPA Superfund Site Leachate Contract

There have been fewer dramatic US nationally funded clean-up up projects in recent years, since more attention has been given to regulating landfills and the operators have been made to line them and show that proper care is being taken to protect the environment from the damage that leachate escape can cause. The following article shows a case where action is being taken to protect water supplies:

The U.S. Environmental Protection Agency (EPA) recently announced that it has entered into an agreement with the General Electric Company and SI Group, Inc. (formerly Schenectady Chemical) to collect and properly dispose of contaminated ground water and liquid leaching from the Dewey Loeffel landfill that is threatening several nearby drinking water wells. The liquid seeping from the landfill, called leachate, and the ground water are contaminated with volatile organic compounds, which can cause cancer in people. The extent and nature of potential health effects depend on many factors, including the level and how long people are exposed to the contaminants.

The EPA is currently collecting the contaminated liquid waste and sending it off-site for disposal. Under the agreement, General Electric and SI will take on the collection and removal of the waste and the construction of a treatment plant adjacent to the landfill, all with EPA oversight. The waste will continue to be sent off-site until the construction of the treatment plant is completed. Treated water from the new system will be discharged to surface water only after the EPA verifies that sampling data shows that the treatment system is working effectively and is capable of meeting stringent state discharge limits. GE and SI Group have agreed to reimburse EPA for certain costs, including an upfront payment of $800,000.

“The EPA has determined that treating the contaminated ground water and liquid at the site is an effective way to protect people’s drinking water wells while the EPA investigation of the site continues,” said Judith A. Enck, EPA Regional Administrator. “The treatment system that will be constructed near the landfill will alleviate the impacts of the hundreds of truck trips needed to dispose of the waste off-site.”

The treatment system to be constructed will address potential threats from the contaminated ground water and eachate and community concerns about trucking the contaminated liquid off-site. A comprehensive long-term study is underway, which will identify permanent cleanup options, called remedial actions, for the contaminated ground water, surface water and sediment associated with the site. The permanent cleanup plan may include changes to the leachate collection collection, ground water extraction and treatment systems.

The Dewey Loeffel Landfill site is located in southern Rensselaer County, approximately four miles northeast of the village of Nassau. From 1952 until 1968, the site was used for the disposal of an estimated 46,000 tons of waste materials generated by several Capital District companies. The waste included industrial solvents, waste oils, polychlorinated biphenyls, scrap materials, sludge and solids. Volatile organic compounds and other hazardous substances have seeped out of the landfill and contaminated the ground water. PCBs have also moved downstream, causing contamination of sediment and several species of fish in and near Nassau Lake.

From 1980 until the site was added to the federal Superfund list in May 2011, numerous investigations and cleanup actions were performed at the site under the New York State Department of Environmental Conservation’s Superfund program. In the fall 2011, the EPA took responsibility for operating ground water and leachate collection collection systems that had been installed by the state.

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Landfill woes far from over - Times Daily

The importance of avoiding landfill leachate escapes to landfill operators is once again made clear in this article which we found recently, where the problem is all about the release of leachate  into the nearby creek. It shows, yet again, how important it is to ensure that leachate is managed carefully. Which means that the city’s municipal solid waste landfill may be closed to new waste tipping, but it’s far from being off the local radar screen.

Here is an extract from the article:

The Florence City Council could vote tonight to pay its engineering consultant $21,130 to investigate the source of a leachate escape in February that ultimately led to the state issuing a notice of violation.

The contract with Highland Technical Services would also authorize the company to take steps to recover leachate — water polluted with garbage — from the cell from which it originally escaped. If that option is chosen, the cost will increase to $55,640.

The council voted recently to close the landfill to municipal solid waste, leaving the remaining space for construction and demolition debris. The landfill was running out space, and the council deadlocked for months on whether to open a final cell or close the landfill and hire a contractor to haul trash out of state. The latter option was chosen as a temporary emergency measure in December because the current cell filled in early January.

In March, the council voted to extend its contract with Waste Connections, which is operating a transfer station for the city.

The notice of violation from the Alabama Department of Environmental Management cited the release of leachate into nearby Cypress Creek during a rain event. The violation is considered serious, and the notice stated a monetary fine could be imposed.

The council’s 3-3 deadlock was broken when Councilman Sam Pendleton and Council President James Barnhart voted to extend the contract with Waste Connections. Pendleton said the violation convinced him the landfill has problems. Barnhart, who had been concerned with costs, said Waste Connections’ guarantee of a long-term steady price helped sway his decision.

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LETTER: Landfill leachate safeguards needed in any sewer deals - MPNnow.com (blog)

Here is an open letter from a resident who is appears to be declaring that leachate from a municipal waste landfill which the Waste Water Treatment Plant operator is presumably happy to accept, which must surely mean that there is sufficient treatment capacity at the Waste Water Treatment Plant to treat it, should not be sent there.

(The video below is for your general information and not associated with this article.)

This seems quite remarkable when around the worl the majority of landfill leachate is treated at sewage works, and for example the World Bank often prefers that it be treated finally at a Waste Water Treatment Plant, that this objection should be being made. Of course, the leachate might contain toxic substances, apart from the usual high strength organic contamination which is always present in landfill leachate. It also might well contain dissolved methane which might make it an explosion risk to discharge into the sewer, and need methane stripping before it is discharges, or, it might actually be more cost effectively provided with initial leachate treatment plant at the landfill site, by installation of a nitrification treatment plant, of which i have designed and supervisied construction of many.

However, just to say this is horrible suff this landfill leachate and must not go to the sewer  or the Waste Water Treatment Plant by tankers, is likely to place a high and unnecessary burden of cost on the community, for little environmental benefit, if any. You can read the opern letter below. Please also visit the original blog article:

Dear Officials (town and city of Geneva):

The residents of the Town and City of Geneva and the Town of Seneca are bearing most of the burden of the off-site environmental problems coming from the Ontario County landfill.  These residents are becoming more cynical about the ability and the willingness of some local officials to stand up and represent their constituents, as opposed to the interests of Casella Waste. Because of that, it seems like a good time to state an important concern about pending sewer negotiations.

Any final agreement must contain safeguards against Casella ever being able to transport leachate from the landfill through any jointly owned/operated sewer line to the Geneva Waste Water Treatment Plant, which discharges into Seneca Lake. Although this battle was fought months ago, that was not a final victory for Seneca Lake and those who drink its water, since leachate is still being trucked to the waste water treatment plant. The appetite of some local officials for leachat dollars apparently is never satisfied. City Council’s courageous decision against a direct pipeline from the dump to the treatment plant must be confirmed for the future in any city-town agreement about sewers.

In keeping with this decision and the concerns of residents, it is essential that any sewer agreements between the Town of Geneva and the Town of Seneca, and between the City of Geneva and the Town of Geneva include specific language preventing Casella or any future operator of the landfill from transporting leachate through city and town sewer lines.

SAM C. BONNEY
Geneva

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Fears of leakage from rotting pile - Nelson Mail

There is no doubt that leachate can be very strog and cause a risk of surface water pollution, fish kils, etc. even where composting is taking place, and controls on where such compost piles are located may be needed. Here is a case where this has been seen as being vitally important.

Please vist the original website by clicking the link at the bottom of the article:

HELEN MURDOCH: A breach in a clay bund wall surrounding an illegal pile of rotting chicken and bark near the Motueka River has raised questions about the waste leaking into groundwater.

The Nelson Mail returned to the site on Thursday and found an overgrown drain from the compost site used by Birdhurst Ltd led directly to a nearby well liner sunk into the ground.

On Tuesday the Tasman District Council's environmental information manager Rob Smith had said that the illegal pile of rotting layer hens and bark would be allowed to remain at the site for the next month until the compost process was complete because moving the heaps before the process was complete would create too much smell.

At the time Mr Smith said the piles were in a compacted clay pit and there was no chance of contamination entering the groundwater – which ran between 2.5 to 3.5 metres below the surface – or reaching the Motueka River, some 200m away.

The situation came to public attention late last month when the Mail was called to the site off the end of Parker St because of concerns over the smell from the estimated 300 cubic metres of rotting chickens and bark.

The company was then fined $750 for breaching an abatement order issued by the council last year requiring Birdhurst to halt the operation.

Mr Smith said on Thursday staff were aware of the slot in the bund. It was to be blocked up on Thursday evening and more bark added to the pile of rotting chickens to reduce the smell.

"We believe that it was part of the previous consent requirement to manage the leachate. The previous consent had leachate management provisions in it. The composting material is isolated from the slot by clean bark and shell material.

"While I do not believe that there is any need to worry about any potential discharge to groundwater we will sample the groundwater next week to put the public's mind at rest."

Mr Smith said staff were following up on the issue of the unconsented compost operation occurring on the site that breaches the volume and odour regulations. 

View the original article here

Ohio EPA Acts on Discoversy Thet Landfill Leachate Could Pose A Threat to Public Health

The phrasing of this article is quite surprising. Elsewhere it has long been recognised that leachate can, if it gets into water supplies, be a major hazard to human health. In any landfill in other than a desert environment there is always enough leachate to jeopardise aquifers and watercourses if these are present in the local geology, and once in an aquifer the leachate may then migrate to be drawn into public water supply wells.

(Please note that the video below is included to point out the hazardous nature of leachate, and is not connected with the article.)

Throughout the EU this has been recognised for nearly 30 years now, since the Council passed a law (Directive) on all EU nations that as a matter of principle makes it illegal to pollute any uderground water, whether used for public extraction wells or not. The journalist who wrote this article is clearly not aware of these facts, howecer, it is good that the dangers of leachate to public health are being treated seriously in Ohio, and the authorities are acting on behalf of the people to ensure they are kept safe. Please read the original article, not just our excerpt below, but follwing the link at the bottom:

The Ohio Environmental Protection Agency proposed rule changes for construction and demolition debris landfills, which could mean more protection for Ohio's groundwater but higher operating costs for some landfills in the Mahoning Valley.

According to officials at the Ohio EPA, acting on a request by Ohio legislators, the agency conducted a leachate study and determined that leachate from Ohio CDD landfills could pose a threat to public health and the environment if it were to be released to groundwater or surface water.

''What we've done is added some provisions for making sure that doesn't happen,'' said Linda Fee Oros, spokeswoman with the Ohio EPA.

If adopted, those new restrictions could apply to two licensed CDD landfills in Trumbull County, Total Waste Logistics LAS LLC in Girard and the Lafarge-owned Lordstown Construction Recovery in Lordstown.

A CDD landfill differs from other types of landfills, including municipal landfills, in that it can only take materials from buildings, said Linda Fee Oros, spokeswoman with the Ohio EPA.

But Tim Page, general manager of Lordstown Construction Recovery, said he does not believe increased regulations on landfill leachate will not hinder operations there.

''Our leachate is not circulated. It's all treated and hooked up to the sewers and sent through the sewers,'' he said.

Page said his company is in discussions with the Ohio EPA regarding the proposed changes, but that they are very early in the process and that nothing has been decided.

Another area being discussed is in the increase in financial assurance required to be paid when licenses are issued each year.

''What they are asking for is more dollars per acre to be spent because the cost of closure has increased over the past few years,'' Page said. ''The materials you bring on site, the fuels and machinery, has gone up. So, there's definitely a need for an increase there of some sort.''

Not unlike other businesses, these types of landfills can be affected by the economy, which could cause them to close. If the business is unable to pay to properly close, the responsibility is then burdened on the state.

''You may have hard financial times and need to close. If the business doesn't generate enough money to pay for those costs, that would be a financial impact,'' Page said.

CDD landfills can only accept debris from construction and demolition activities; packaging resulting from the use of construction materials where the packaging is incidental to the load; tree stumps, trunks and branches exceeding 4 inches in diameter where the branches are clean of leaves and small branches; and asbestos-containing materials as long as a NESHAP air permit has been granted.

A CDD landfill is required to keep records of accepted and rejected waste loads, activities and the working face, preventing fires, proper management of surface water and leachate and prevention of nuisances or health hazards.

They are also required to monitor ground water if the facility is located near wells or an aquifer.

The process to have the proposed changes becoming rules is still in its early stages and the Ohio EPA is working to fine tune their proposals.

''At this point, we are looking at the comments we received and are working to incorporate those into our rules if changes are needed,'' Oros said.

A hearing will be held with Ohio's Joint Committee on Agency Rule Review regarding the possible rule changes. No date has yet been set for the hearing.

View the original article here

Leachate Collection and Treatment Facility Gets City Landfill Site and Student Thesis

Locals will be pleased abut new invetsment in environmental protection measures at the Merrick landfill site, as in the quotation which follows:

NORTH BAY, US - Engineering plans for a leachate collection and treatment facility at the city's Merrick landfill are ready to be drafted after council approved a $1.7 million expenditure during its March 5 meeting.

"Once completed, these plans will be presented to the Ministry of Environment for comment. We expect that to be completed by the end of the summer and hope to be able to tender out the construction of the project by late fall," said North Bay's manager of environmental services John Severino.

It is expected the leachate treatment facility will be operational by the spring of 2014.

The leachate treatment system has been designed by Conestoga Rovers and Associates, with input from Queen's University students who have been actively studying the city's landfill site and estimating future waste management needs.

"We actually have students at Queen's doing their thesis on our site," said City engineer Alan Korell, "and the National Research Council has put money in as well."

Total costs of this project have been budgeted at $5 million, money well spent according to Korell. He says the landfill site, "is the city's biggest opportunity to make a positive impact on the environment."

Severino says the system the city has chosen allows for the treatment of the liquid seepage so it can be directly returned to the environment. "It is also a flexible system in order to address any future concerns and is part of the whole Green Plan for the city."

The Merrick landfill, opened in 1994 with a footprint of 40.5 acres and has a life expectancy of 20 more years. Divided into 10 cells, "the first cells were naturally attenuated," said Severino, "where the leachate was allowed to run into the ground and be naturally treated. When we opened cell five, we put down a clay liner to collect the leachate, and have done the same with cell six, recently opened."

The treatment project is a complement to the methane collection system already part of the landfill operations.

"Currently we are collecting and flaring the methane gas. This system has only a one-twentieth impact on the environment compared to the natural process," said Severino. "Once the cogeneration plant is operational, the methane will not only produce energy for the area but will also be used to heat and help facilitate the leachate treatment system."

North Bay's energy from gas project, is the first to receive approval under the province's new Green Energy Act and is targeted to start production the end of June. The cost of this initiative was also $5 million.

"At peak capacity the plant should generate 1.6 megawatts of electricity," said Korell. "Enough to supply many of the homes in the area and stabilize that end of the city. It's about the equivalent of 1,300 homes."

The cogeneration plant will offset about 45,000 tons of carbon dioxide annually.

North Bay Hydro received approval for the renewable energy project in June 2011.

"Our philosophy, when it comes to the landfill site, is to limit what's going in there, and to optimize what's going on," Korell said.

Korell and Severino are excited about the city's approach to waste management, and are already eyeing starting the expansion planning process in about 10 years in order to have everything in place at the end of the current certification period. They both feel the city is, "ahead of the game in Northern Ontario," and they want to see it stay in the environmental lead.

"We are already diverting as much as 40 per cent of our waste, through recycling," said Korell, " and we're working to make the current landfill site last as long as possible.

"We're also fortunate that the city owns lots of land where the site is now, so we'll be able to expand, rather than have to look for a new location."

As the first such site approved to produce biogas, "we've sort of been the provincial guinea pig," said Severino. "MOE has been using us as a demonstration site and bringing people to show them what a well managed landfill is like."

Mayor Al McDonald says the landfill site initiatives are part of council's commitment to the environment and to future generations.

"These projects see over $10 million invested at the Merrick landfill site," he said, " to ensure the City's future needs are satisfied in an environmentally responsible way."

View the original article here

New EPA Leachate Monitoring Rules Affect Local Landfills

New landfill rules will mean increased costs for old landfills in the US County, and include, five key areas, for a post-closure care period, post-closure care financial assurance, more post-closure care period imonitoring if there are judged to be health or environmental effects, and a procedure to adjust final closure financial assurance.

The full details are given from the Zanesville Post article which descrobes them, below. Please visit the original site:

ZANESVILLE -- The Ohio Environmental Protection Agency has proposed new rules that would require the state's licensed construction and demolition debris landfills to regularly test groundwater for an expanded number of contaminants.

Two of the state's 55 licensed landfills which would be subject to the new rules are local -- Sidwell Materials' site off of Limestone Valley Road in Newton Township and the County Road 286 landfill in Coshocton County.

Sidwell Materials Asbestos Hazard Evaluation Specialist Drake Prouty said the company will abide by whatever rules and regulations ultimately are set forth by the agency.

He said that EPA representatives visit the landfill at 4620 Limestone Valley Road quarterly and for unannounced spot testing of groundwater at the 9-acre site, and no problems have been found.

A legislative study committee and the EPA proposed tougher regulations regarding water monitoring or leachate at the bottom of landfill sites in 2005, but backed off after officials complained the new regulations would be too expensive to comply with.

That proposal would have allowed for 64 different toxic chemicals to be tested for, instead of the 19 currently required by the EPA. The new proposal expands that number to 77 pollutants which could "leach" in to groundwater supplies, including iron, sulfate, manganese and even toxic adhesives.

Based on the prior study which determined lthat landfill leachate poses a threat to public health and the environment if released to ground water or surface water, and public comments received on the draft rules issued earlier this year, Ohio EPA developed the current proposed rules.

The amended proposed rules focus on five key areas:

- Five-year post-closure care period.

- Post-closure care financial assurance provided by the facility.

- Extension of post-closure care period if there are health or environmental effects.

- A procedure to adjust final closure financial assurance with the issuance of an annual license.

- Monitor landfill eachate at the bottom of the landfill for an established list of contaminants, and if detected, monitor ground water for the detected contaminant.

View the original article here

Anaerobic Digestion News: Biogas from Anaerobic Digestion Can Help Save Our ...

Anaerobic Digestion News: Biogas from Anaerobic Digestion Can Help Save Our ...: Our Angry Dragon cartoon below is intended to be funny and provokes thought about why biogas from anaerobic digestion can help save our pla...

Odour Killing Solution From St Clair, Clean Harbors is a Dangerous Idea

While we are sure that everyone has great sympathy with the locals in St. Clair, who should not have to suffer this odor for one more day, as an experienced leachate treatment engineer it concerns me to read about the solution being adopted. Covering these foul smelling lagoons, which contain a, no doubt, high level of organic contamination is a dangerous route to take. The largely anaerobic leachate which probably over time have also developed an organic sludge below the water which is also anaerobic, will be generating biogas. In fact there are many examples of anaerobic digestion (biogas) plants built on purpose using acetogenic organic wastes in a comparable manner to this.

So, please take care about going down the route of covering leachate lagoons and providing almost no ventilation. If you do, take care to observe good explosion risk assessments (in the EU the ATEX Directive applies) and implement goode safety procedures on-site. In the past it has been seen as a much better idea to dose the leachate as it enters the lagoons with an oxidising agent such as hydrogen peroxide, or even potassium permangenate. Once in an aerobic condition throughout, no more methane will be generated, and the operator could then commence aeration of these lagoons, but aeration into anaerobic conditions at first would just make the odor more pronounced. (If you need expert help on solving leachate odor problems contact us at www.leachate.co.uk .) The article extarct follows. Please visit the link at the bottom of this page to see the original page:

ST. CLAIR  TOWNSHIP - Clean Harbors has spent nearly $1 million on corrective action since last August when an overwhelming stench began impacting neighbours of the hazardous waste facility.

"The sheer volume of exposed leachate couldn't be addressed by snapping our fingers," said the company's compliance director.

Mike Parker, a handful of consultants, and Clean Harbors' managers, spoke to about 35 residents Wednesday at an open house at the Royal Canadian Legion in Corunna, assuring them that months of sickening odour incidents will soon be over.

While some neighbours disagree, company brass are confident the stink is a result of too much leachate at the Telfer Road site.

Since August, Clean Harbors has incinerated approximately 20 million litres of leachate and emptied one of its holding ponds.

By late February, the company expects to completely cover its two leachate ponds with engineered roofs and will easily meet the deadlines directed by the Ministry of Environment, Parker said.

The ministry has ordered Clean Harbors to address its odour issue and reduce the volume of on-site leachate by May.

"We're doing a lot of work that will ultimately reduce the leachate,"

Parker said. "We're doing everything possible to be sure the odour is gone. I'm very confident the major source will be eliminated by May.

"We wouldn't do all this and spent this kind of money if it wasn't going to be affective," he said.

But neighbours at Wednesday's open house weren't so confident.

The odours have impacted their quality of life, made them nauseous, stung their eyes and sent them to emergency.

"You are interfering with my enjoyment of my property," Jim Stenton of Petrolia Line told Clean Harbors' general manager Jim Brown.

Stenton asked Brown why the company doesn't put out a warning through the community warning system known as CVECO when odours are bad.

"It would be better if I had warning so I could get out of my house,"

Stenton said.

"For an odour complaint?" Brown answered. "I don't see it that way."

But, Clean Harbors does alert the Ministry of Environment, he added.

"And once the leachate is under the cover, it will eliminate that septic smell," Brown said. "You'll never get rid of all the odours completely but the really bad smell should be gone."

Clean Harbors has applied for ministry approval to vent the engineered roofs, a move that the neighbours oppose.

"I think everyone is pretty upset about it," said Lori Vokes who represents about 100 area residents.

"They said they were installing airtight covers and now they want to vent them."

The public has until Feb. 12 to comment on Clean Harbors' application to vent.

"We hope enough people will object to make the ministry take a closer look at the application and not just rubber stamp it," said Vokes.

The application can be viewed at www.ebr.gov.on.ca and is number 011 5467.

If approved, each leachate pond will have one vent measuring two inches in diameter, said Parker.

"We'll use it two or three times a week for three to five minutes at a time. If there's a bad odour, we'll shut the valve," he said.

The vents are necessary to release any trapped air under the cover and ensure the ponds work efficiently, Parker added.

Odour complaints related to Clean Harbors' operation continue, said St. Clair Township Mayor Steve Arnold.

Incidents are less frequent and not as intense but are still occurring, he said.

"Usually there isn't a problem with odours at this time of the year,"

said Vokes. "But the last six months have been completely out of the ordinary.

"It's making people nervous about the spring."

Sarnia Observer

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