Biosolids Forest Fertilization Project

Questions & Answers

The following is a sampling of some commonly asked questions about biosolids application projects. However, we cannot respond here to all possible questions. If you have any questions that have not been covered in this document, please contact Marise Wickman, R.P.F. at 753-3245 ext. 2232 or e-mail marise.wickman@viu.ca. Thank you.

What are biosolids and how are they produced?

Biosolids is the organic solids which settle out when wastewater (sewage) is processed at a Waste Water treatment plant. Wastewater entering a treatment plant is first screened to remove large objects, then held in tanks where the suspended organic matter settles out by gravity to form biosolids. The biosolids is removed and processed in large tanks called “digesters.”
In the digesters, bacteria break down the biosolids, reducing its volume by half. Digestion also significantly reduces odours and disease-producing organisms. After it is dried, biosolids looks much like garden soil and has a slight musty smell.

What is in biosolids?

Biosolids is comprised mostly of water, sand, nutrients and organic matter (also called humus). Humus helps soil to retain water and nutrients so they are available for plant growth. Biosolids also contains nitrogen, phosphorus and other nutrients that plants need for growth, as well as trace elements and micro-organisms.

Why does Vancouver Island University want to apply biosolids to sites in its forest?

The Vancouver Island University Forest is dedicated to demonstrating modern practices in forestry and ecology. We have forest sites where a lack of nutrients severely limits tree growth, and we have available to us an abundant supply of municipal biosolids which can provide those nutrients. This project will provide a model for how we can improve the health of our forests in an ecologically sensible way and help the Regional District of Nanaimo divert biosolids from its landfill site.

Why are biosolids such a good fertilizer?

Biosolids are superior to commercial, chemical fertilizers in many ways.

• Biosolids contains humus, which helps soil to retain water and nutrients.
• Biosolids contains significant amounts of the traditional fertilizers: nitrogen, phosphorus and potassium, as well as many trace elements essential for healthy tree growth.
• Nutrients from biosolids release over a much longer period of time, so that trees have a sustained source of nourishment.
• Recycling biosolids as a fertilizer turns two problems - biosolids disposal and poor forest soils - into an environmental solution.

How do biosolids help in making trees healthier?

Our 1992 biosolids forest fertilization project has demonstrated remarkable increases in tree growth - from 50% to 400%! Biosolids do not produce mutant trees, it helps trees in nutrient-poor areas to achieve their maximum natural potential as though they were growing in ideal conditions. Trees treated with biosolids also appear healthier; needles and buds are longer, greener and more numerous.

Are there any public health risks from biosolids?

There is a slight chance that someone could get sick if they actually ate biosolids. Otherwise, the risk from human contact with biosolids is negligible. Sewage treatment plant operators regularly work with and around biosolids with no ill effects. Treatment through the mechanical digestion process kills 99.9% of the micro-organisms in biosolids; the rest die off naturally once they are exposed to sunlight, lack of moisture and low pH levels in the soil.

The proportion of trace elements in biosolids requiring careful monitoring is very small - less than 1/10 of 1%. These include such things as copper, lead, mercury and zinc. These elements enter the sewer system from residences and storm water runoff. Most of these minerals actually benefit plant growth, but they can be harmful in excess concentrations. That’s why the composition of biosolids used in land applications is carefully analyzed and controlled. Only biosolids which meet the Ministry of Water, Land and Air Protection’s Organic Matter Recycling Regulation (OMRR) is used in land application projects.

Is the application site in Lantzville’s watershed or over Lantzville’s aquifer?

The Vancouver Island University Forest is located in the Flynfall Creek watershed which is not part of Lantzville’s watershed. The most recent studies delineating Lantzville’s aquifer show that Vancouver Island University's Forest is outside the boundaries of this aquifer. Monitoring data from our 1992 biosolids project shows that biosolids had no detectable impact on ground or surface waters.

How will the biosolids be applied?

Dried biosolids will be trucked to one of four storage sites located near the end of Weigles Road. After the sufficient quantities required for economic application, the biosolids will be loaded into a special applicator vehicle. The applicator vehicle has a large box which then feeds a high speed side throw discharge unit called the ‘aero-spreader’. The biosolids will then be carefully applied over the forest site in pre-measured amounts.

Is there any danger of airborne bacteria or viruses being blown onto our property when biosolids is sprayed?

Studies have shown that a person would have to be continually exposed for 2,500 hours 100 metres downwind of a site to be harmed by airborne viruses from a biosolids spray application. Because the chance of this kind of exposure is essentially nil, researchers have determined that the viruses in sprayed biosolids do not pose a public health threat. Furthermore, the biosolids material is too dense and cohesive to be blown 1 km to the nearest residential property.

Will there be effects on well-water for the residents on Dumont Road or on the water in Brannen Lake?

The monitoring results from the 1992 project showed that biosolids had

• No measurable impact on ground water
• No measurable impact on nearby surface waters
• No detectable impact on the five nearest residential water wells

Extensive research from our 1992 biosolids project has shown that trace elements introduced into the soil through biosolids projects generally do not move far below the soil surface, usually within 5 to 10 centimetres. Even during a very severe rainstorm, biosolids that have not yet been absorbed into the soil will move only a few metres. This would not affect the nearest residence to our project site, 1 km away. Nevertheless, we will assure the safety of water supplies in the following ways:

• we have chosen sites without steep slopes
• we will provide 30 to 60 metre buffers from water courses

Will access to the forest be restricted during or after the biosolids application?

Public access to the forest will be limited during the field operations, which are tentatively scheduled for short periods throughtout the year. Afterward, the public will be free to use the forest. However, we will be posting signs asking people not to use sites where biosolids has been applied. These sites will comprise 50 hectares each year out of the forest’s total 1,703 hectares. We will also control and monitor all aspects of our project to ensure protection of public health and the environment. This includes posting signs advising people that biosolids have been applied to the sites. We keep these signs up for three years to ensure proper notification.

What other controls will protect public health and the environment?

This project will require a Land Application Plan to be written by a qualified, registered professional. The Land Application Plan must meet all requirements set out in the Organic Matter Recycling Regulation (OMRR) and is subject to audit by the Ministry of Water, Land and Air Protection staff.

To protect public health and the environment, we have or will:

• obtain an independent analysis of the biosolids composition
• analyze the ecology of each site
• apply biosolids in an amount appropriate to the site’s unique ecology
• choose sites without steep slopes
• strictly control the on-site storage and application procedures
• provide adequate buffers from water courses
• analyze soil samples at application site to ensure addition of biosolids does not result in excess of any trace element.

What is the Greater Vancouver Regional District’s involvement?

The GVRD is not participating in or providing any materials for this project. 90% of biosolids for this project will come from the Regional District of Nanaimo Waste Water Treatment facilities. The remaining biosolids comes from the District of North Cowichan’s Chemainus WWT plant.

How much biosolid material will be used?

The project will use approximately 1,250 dry tonnes of biosolids or 4,500 bulk tonnes (approximately 450 dump truck loads).

What will the fertilized sites look like?

The sites will appear to be covered by a rich, dark topsoil material to a depth of two centimeters. Because this is a drier application method than was utilized in the 1992 project, little if any material will remain on the trees.

Where else has this type of project been done?

Treated biosolids have been widely used in Canada, the United States and Europe for over 40 years. The most common use is as an agricultural fertilizer. Kelowna has used its biosolids to fertilize orchard trees since 1995. Closer to home, farmers in Parksville and Qualicum have been using biosolids from the French Creek Pollution Control Centre to fertilize their agricultural land. Seattle, Washington has 20 years of experience with applying biosolids to forest land. The Greater Vancouver Regional District completed a three-year research project with the University of British Columbia to demonstrate the potential for recycling treated biosolids as a forest fertilizer. Vancouver Island University’s 1992 project demonstrated significant increases in the health and growth rates of trees without detrimental effects on the environment.

Is there sufficient soil depth on site to apply biosolids?

The sites where biosolids are to be applied have been carefully surveyed and classified. Soils depths in the proposed treatment areas are at least one metre. Our 1992 project, which also treated sites in the immediate area, showed that soils are adequate to support trees and provide a buffer to any movement of materials into groundwater.

Vancouver Island University Forest Fertilization Project
Comparison of Trace Element Content with
Ministry of Environment Guidelines

Dry Weight Concentrations – (mg/kg)
(Milligrams of Trace Mineral per Kilogram of Dried Biosolids)

Trace Elements	MWLAP Guideline Level	1992 Malaspina Biosolids Project	2009 VIU Biosolids Project
Arsenic, AS	75	5.1	< 10
Cadmium, Cd	20	4.9	2.1
Cobalt, Co	150	7.1	4
Chromium, Cr	1060	71	42
Copper, Cu	2200	965	965
Mercury, Hg	15	8	4.67
Molybdenum, M	20	5.3	6
Nickel, Ni	180	35	21
Lead, Pb	500	212	44
Selenium, Se	14	5	< 2
Zinc, Zn	1850	791	949

Marise Wickman, R.P.F. 1/8/2010