What began in 2010 has now come to a good and successful end, to the delight of all involved and, in particular, of the residents of the Bad Hersfeld marketplace. Four years ago, on behalf of Abwasserbetrieb Bad Hersfeld [Bad Hersfeld Sewage], we determined by means of camera inspection that significant rehabilitation measures needed to be implemented in order to repair the outdated sewer system including the house connections underneath the marketplace in Bad Hersfeld. The aim: today's environmental requirements and the resulting structure and approval management constraints must be met for the benefit of the populace. Fragmentation, root penetration, leaks, cracks and even complete breaks in the sewers, which are more than 80 years old in parts, came to light during the video inspection. This was followed by assessment of the damage and classification into damage categories depending on the damage pattern by the authorized engineering firm AQUA, Ingolstadt followed by the call for tenders for the urgently needed rehabilitation using both open trench and trenchless methods. AARSLEFF Rohrsanierung GmbH was awarded the contract for the rehabilitation using the trenchless method in collaboration with its local and long-term partner Willi Schwalm, owner: Martin Schwalm, registered trader.
"The job in the most central point of Bad Hersfeld was a significant challenge for all involved", says Michael Draband, Schwalm Kanalsanierung construction manager together with AARSLEFF site manager, Christopher Mock. "The numerous phases of work had to be timed perfectly and passed on hand in hand between the various rehabilitation companies in order to keep traffic disruptions to an acceptable level for residents and businesses. "Yes, we did well," stresses Volker Ehrich, Deputy Operations Manager at Abwasserbetrieb Bad Hersfeld, and Thomas Weber, Aqua engineering firm, "to instruct experienced teams who work well together for this construction site and for the individual elements of rehabilitation. As a result, coordination is of the utmost importance, as proven by both AARSLEFF and SCHWALM, in particular when something is not running so smoothly."
"Before AARSLEFF was able to generally start rehabilitation of the main sewers using the trenchless method with the pipe lining procedure at Am Marktplatz in Bad Hersfeld in April 2014," says Christopher Mock, "we first instructed our partner, Schwalm Kanalsanierung, to clean the sewers, then to remove fragments and root intrusion and to align any displacements at the pipe connections. Important foundations were thus laid in order to initiate the next step, which was the pipe lining procedure. For this, a long hose coated with synthetic resin was guided through the damaged sewers and pressed against the sewer walls by means of water pressure (like a long, inside out stocking). Once this inner cladding had cured, all the cracks and similar damage were dealt with, resulting in a new sewer within the sewer with a service life of at least 50 years."
In comparison with "open trench" methods, this procedure not only saves a significant amount of time and money, but also makes rehabilitation on a large scale, as was the case here around the Bad Hersfeld marketplace, possible. Even when this procedure occasionally results in noise pollution and traffic disruptions, it still looks very good in comparison with the "open trench method" which has excavators tearing up the streets for weeks.
In order to restore unobstructed drainage to the households as quickly as possible after the installation of the pipe liner, Schwalm Kanalsanierung re-milled the house connections which were closed off by the pipe liner immediately after hardening.. The house connections were thus reconnected to the main sewer by means of hat seals. Complex procedures which were carried out, divided into individual work phases and fixed time windows umpteen times across a period of several months, professionally and with all due care and attention by the AARSLEFF - SCHWALM team in the Bar Hersfeld marketplace. "There was always one uncertainty or another," remembers Michael Draband, "but we were always able to overcome them. Construction only had to be stopped once. That was less because of us, though, and more because of the Bad Hersfeld festival in August 2014. Understandably, that meant a six week unscheduled break for everyone involved with the construction site. Over the last few days, however, we have been able to carry out the last of the works to everyone's satisfaction and the marketplace is fully rehabilitated."