Since the stream adjacent to the facility is a Natura 2000-protected watercourse, it was especially important to protect stormwater from contamination. The stream is subject to strict environmental regulations aimed at preserving biodiversity, making efforts like this essential.

Implementation

During the site visit, catch basin filters with oil absorbents were installed in five selected storm drains and one stormwater channel at the facility. The filters are made from a durable textile material that captures particles and debris while allowing water to pass through an overflow outlet, even when the filter is full. The oil absorbent used in the filter is made from by-products of the cellulose industry and is designed to repel water while effectively absorbing oil.

Evaluations and testing

To assess the performance of the filters, several evaluations were conducted throughout the project. The primary focus was on their ability to reduce oil in the water and to capture particles before they reached the storm drains. Laboratory evaluations also examined the filters’ effectiveness in reducing suspended solids and metal concentrations in the water.

The following evaluations and tests were carried out:

• Field observations and site inspections

• On-site water sampling

• Weighing to calculate particle reduction

• Inspection of the filters and collected material

• Laboratory evaluation of the filter and oil absorbent

• A total of four site visits were conducted at the facility to perform these evaluations

Analysis

All analyses were performed by ALS Scandinavia AB and included the following parameters:

• pH

• Conductivity

• Total nitrogen

• Total phosphorus

• Suspended solids

• Oil index

• Fractionated petroleum hydrocarbons

• Metals

Eight analyses were conducted in total, and the results were compared with the City of Gothenburg’s guideline values for stormwater and construction dewatering (Göteborg Stad, 2013).

Results

The tests showed that the catch basin filters with oil absorbents reduced oil concentrations in the water by 85–90%, even at high levels. In addition, levels of suspended solids and metals were also reduced in the water passing through the filters. The filters captured a significant amount of solid pollutants, improving water quality and reducing the risk of clogging in storm drains and stormwater systems.