A simple solution how to remove heavy metal from your runoff water. With Leca LWA, design by WEREC. Including water storage and water retention.

1. A COMPLETE SOLUTION
FOR PURIFICATION AND
DETENTION OF STORMWATER
A combined solution
By combining two proven methods,
Leca has, in collaboration with WEREC
Water Ecosystem Recovery, developed a
solution that provides effective removal
of contaminants while providing
storage capacity.

2. 2
WEREC AND LECA®
A complete solution for purification
and detention of stormwater
As knowledge about storm water and its pollution
increase, higher demands are made for more effi-
cient treatment of, among other things, oil pollu-
tion, phosphorus and heavy metals. At the same
time, increased rainfall and more extreme weather,
increase the need for water detention. This is es-
pecially true in fast growing areas where natural
detention is being replaced by buildings or other
hard surfaces.
Combined solution for managing
water quality and volume
By combining two proven methods, Leca Internatio-
nal has, in collaboration with WEREC Water Ecosys-
tem Recovery, developed a solution that provides
effective removal of contaminants while providing
storage capacity.
Investment costs are low compared to conventional
solutions and operating costs are very low because
the concept is completely passive.

3. 3WEREC and Leca® - a combined solution
28 mm/day
A cloudburst today at 20 mm/day would correspond to
28 mm/day in the future - SMHI (Swedish Meteorological
and Hydrological Institute)
Solution with cassette or filter bed
The Leca material, Filtralite P, separates sus-
pended material, phosphorus and heavy metals,
while the high porosity of the material provides
a significant storage capacity. Depending on the
local conditions, the filter can be installed as a
cassette solution or as a filter bed. The solution
with a filter bed is designed for conditions where
there is access to park areas or an unpaved sur-
face, adjacent to the hard surfaces, which allow
for material exchange with excavator. In narrow
environments like central cities, the cassette
solution can be lowered down under ground and
material exchange takes place through the ins-
talled manhole covers using a vacuum truck.
The solution is designed according to WEREC’s
filter technology, which provides high degree of
purification and a life span of at least 10 years.
After this period the filter material is simply re-
placed. Werec’s technology ensures optimal flow
and contact time, all based on the conditions of
the catchment area. Dimensioning also consider
regulation of maximum permissible limits, set
by the municipality.
Oil compounds are separated in a pre-filter,
consisting of an organic filter media. The pre-fil-
ter further contributes to metallic separation.
This filter is also designed with WEREC technolo-
gy and is dimensioned to extend the life span to
10 years.
• Cleaning and detention of water
• Cassette- or filter bed solution
• Passive solution - low maintenance
• Easy to replace filter material
• Free geometric design
• Low weight for roofs or courtyard installations
• Robust and proven technology
• Pending patent application

4. 4
In municipal water system
Many municipalities are now planning their
water management strategies to cope with in-
creased flows in a future climate. The filter beds
or cassettes can be dimensioned to contribute to
detention capacity, for example, with volumes of
1-2 year flows or even more.
The cleaning function in terms of pollutants is
particularly high, adapted to research findings
that have highlighted leakage problems from
many conventional filter types. Our solution is
based on a larger filter volume where the filter
media is replaced by excavator or vacuum truck,
and much less frequently, e.g. every 10 years. The
filtration capacity reduces the amount of pollu-
tants to levels below the guidelines defined by
the municipalities.
After installation, the filter is covered and the
ground can be used as a gravel parking lot, play-
ground or green area. The main bed has suffi-
cient buoyancy without reinforcement.
Examples of installations
In Örebro municipality (Sweden), a storm water filter according to the cassette principle
was installed in 2017. The primary purpose of the installation was to separate oil pollution
and phosphorus. Dimensioned flow rate is 10 l/s and the estimated life of filter material is
10 years.
In Älvsjö, Stockholm, a cassette filter is installed in December 2017, with the purpose to
separate phosphorus and metals. Dimensioned flow is 20 l/s.

5. 5WEREC och Leca® - a combined solution
Property owners
The technical solution is designed to fit both
municipal water systems and privately owned
properties. So far, it has been difficult to achieve
profitability for the property owner when both
detention and purification has to be reached.
With our solution, the property owner can do
just that, and at the same time earn a great deal
by manage the storm water themselves. Even
owners of smaller properties can get these bene-
fits if they merge and share a common facility.
Economics and finance
With our technology, the property owner might
actually earn to manage the water themselfes.
In many municipalities, you will then avoid the
municipal usage fee. In 10 years, the total cost
for discharge will be significantly higher than the
investment and operation of our facility. We will
help you to design the plant to suit your local
conditions. We take into account the guidelines
and tax regulations that apply in the municipa-
lity. Contact us for more information, dimensio-
ning and quotation in your project.

6. 6
Cleaning effect and storage
capacity
Table 1 shows examples of reduction for various
pollutants, measured on actual storm water
over a period of 6 months. The values may vary
depending on incoming levels of contamination,
contact time, etc. The filter can of course be di-
mensioned to increase separation even further.
When dimensioning the filter to typical muni-
cipal limits in terms of metals and phosphorus,
the plant has a storage capacity equivalent to
Table 1
approximately 60% of a six-month rain for 10
minutes and 40-50% of a one-year rain. Already
at that size, the filter provides a significant sto-
rage capacity which contributes to an even flow
downstream. If the plant needs to store a one-
year rain completely, or a two-year rain (about 8
mm in 10 minutes) it can also be dimensioned to
cope with these water volumes.
Substance
Phosphor
total
Phosphate Chromium Copper Nickel Lead Zinc
Reduction % 63,4 59,9 67,0 64,2 64,7 79,2 92,9

7. 7WEREC och Leca® - a combined solution
Price example
• 50 m3
cassette filter for 0.5-1.5
hectares of hard surface: Approx.
80.000 €
• 500 m3
cassette filter for 7-13 ha
hard surface: Approx. 450.000 €
• 100 m3
filter bed for 1-3 hectares of
hard surface: 60.000 €
• 500 m3
filter bed for 7-13 ha hard
surface: 220.000 €
The final dimensions of the filter de-
pend entirely on the purification requi-
rements that has to be met and also
required detention capacity.
WEREC Water Ecosystem Recovery AB
Sam Ekstrand
+46 70-399 85 11
sam.ekstrand@werec.se
werec.se
Check filtralite.com for your local sales
representative.
Contact

8. NOV 2017