In Örnsköldsviks municipality there are both mountains and valleys in an area of 62 x 62 square kilometers. The handling of the water & wastewater is divided into the five areas Bjästa, Bredbyn, Björna, Husum and Centralorten. The scattered areas are coordinated by the common surveillance system ABB PC Manager. The fringe areas have machinists who start from the one and the same control system and work with both the water & wastewater systems.  They are relocated in the fringe areas and share an office with other municipal activity in that specific area. “This organization is due to the fact that they once were separate municipalities,” Sten Ljungberg, process engineer at Örnsköldsviks municipality, explains. To be able to communicate within these areas Örnsköldsviks municipality has chosen Radius digital radio communication solution - Radius PDR. When it comes to water it could be equipment to rise pressure, water plants, measuring points and reservoirs that need a safe communication, and with wastewater it could be purification facilities and pump stations.

Separate but synchronized systems
Each area has its own surveillance system, but the machinists can get connected to the other systems to control the other areas’ facilities. The ordinary procedure is that an alarm is handled at the operational control centers, but each area is connected to the municipality’s emergency center KAC. In KAC, a few designated alarms that have been prioritized by the operational management arrive. Different criterions, for example what time of the day it is, which day at the week it is, control which alarms go directly to KAC and which ones could be put on hold until regular working hours. From the fire station in the center of Örnsköldsvik, the alarms are supervised and on call-duty personnel are sent out to all of the areas.

Both VHF and UHF in the same system
There are PDR masters in the different areas that connect the facilities to the SCADA system. Usually, a master unit is handling the area’s slave units, but in Bjälsta there are two master units; one in the operational control center and one in Sidensjö, 19 miles away, that are connected via a fixed line. There are about 120 PDR slaves in the municipality. In most cases Örnsköldsviks municipality uses UHF, but in Gålnäs, that is part of Centralorten, VHF is also used. “Since the farthest facility is more than 19 miles away, it is better to use VHF” Sten Lundberg explains.