The MDSE Mitteldeutsche Rehabilitation- und Entsorgungsgesellschaft mbH, as a project developer, permanently operates the hydraulic protection of the Freiheit III landfill site on the basis of an official order.
As the landfill operator, MDSE mbH is responsible for the proper lifting, collection and discharge of accumulated groundwater and surface water from the landfill area.
_
The hydraulic protection of the Freiheit III landfill is intended to keep it largely dry by lowering the groundwater surface to 1 m below the bottom of the landfill, so that material leaching processes from the dump body into the groundwater are prevented.
Due to both geogenic and anthropogenic reasons, the elevated groundwater is highly mineralized water, which leads to considerable precipitation and deposits (mainly iron hydroxide) throughout the drainage system. These deposits and deposits must be removed as part of regular maintenance work in order to ensure the functionality of this security measure at all times.
The services for cleaning hydraulic protection systems are carried out on the basis of a maintenance plan and are the subject of this tender.
The partial services to be provided in this context are awarded by the MDSE.
The subject of this inquiry is the following services for cleaning the hydraulic protection systems and the surface drainage system:
- Cleaning pressure pipe DN 400 (1,260 m), TV examination of pressure pipeline
- cleaning free slope channel DN 800 (2,920 m), TV examination clearance channel
- cleaning flow channel passages, cleaning inlet chambers sedimentation tanks 1 and 3, cleaning pressure pipes, individual wells into the flow channel
- cleaning passages surface drainage system
- Cleaning pump stations 1 and 2
- Cleaning pressure pipe DN 400 from pumping station 1 to basin 3 inlet, TV examination of pressure pipe DN 400 (optional)
- cleaning sedimentation tanks 1 and 2 as well as sludge dewatering
- Sedimentation tank 3 cleaning and sludge dewatering (optional)
- vegetation removal sedimentation basins 1 to 3
- Recycling/returning/disposal of cleaned and washed goods/dewatered sludge
- documentation of the work
_
It is planned to conclude a contract for an initial period of 3 years in the period from 07/2022 to 06/2025 with the option of a one-time extension of benefits for a further 2 years until 06/2027.
The scope of services to be provided in principle can be presented as follows.
_
1 cleaning pressure pipe DN 400 (1,260 m), TV examination of pressure pipeline
Cleaning, including pipe emptying, must be carried out within 48 hours for security reasons (limited buffer capacity of the sedimentation tanks).
Pressure line cleaning is to be carried out using combined high-pressure rinsing and suction technology (high-pressure water technology - standard pipe cleaning process, working pressure up to 200 bar).
The cleaning result must be documented by subsequent TV inspection.
The DN 400 pressure pipeline must be cleaned annually.
_
2 Cleaning free slope channel DN 800 (2,900 m), TV examination of free slope channel
The cleaning technology must be selected or specified in adaptation to the structural properties of the individual pipeline sections.
To clean the culvert from building VIII-1 to structure X, it is essential to use special equipment that ensures that the tool slides in the pipe without damage and prevents damage to the cement mortar lining (alumina cement) of the cast sewer pipes.
Cleaning, including culvert emptying, must be carried out within 48 hours for security reasons (limited buffer capacity of the sedimentation tanks).
The cleaning of the DN 800 free slope duct must be carried out every 3 years.
_
3 cleaning passages flow channel, cleaning inlet chambers sedimentation tanks 1 and 3, cleaning pressure pipes individual wells into the flow channel
The 3 pipe passages located in the open channel with a total length of approximately 57 m (brushes or with jet pipe/nozzle under packing/vacuuming) must be cleaned.
The inlet chambers at basins 1 and 3, each with a chamber volume of approximately 20 to 25 m3, must also be cleaned by sucking off the sludge deposits in the chambers and blasting off the adhesions/landings on the concrete surfaces/edges.
The cleaning of the pressure pipes of the individual wells into the open channel is optionally provided depending on the degree of contamination to be detected.
The cleaning of the flow channel passages and the cleaning of the inlet chambers of sedimentation basins 1 and 3 are planned annually.
_
4 cleaning passages surface drainage system
The object of service is the cleaning of all pipe passages of the surface drainage system by means of brushes or with a jet pipe/nozzle under packing/vacuuming.
This applies to a total of 12 outlets with DN 400 to DN 1400.
The cleaning of the passages of the surface drainage system is planned annually.
_
5 Cleaning pumping stations 1 and 2
The chambers of the 8.50 m deep pump receiver of pumps 1 and 2 of the two pump stations must be cleaned regularly. The water-sludge mixture must be extracted (approx. 20 m³) using combined high-pressure flushing and suction technology and access to the feed chamber via the duct. The walls of the pump template are to be radiated into the pump templates with personnel entry.
The pipeline (suction line) from the monk to the pump receiver must also be cleaned in both pumping stations.
With current knowledge, pump station 1 must be cleaned annually and pump station 2 every two years.
_
6 Cleaning the pressure pipe DN 400 from pumping station 1 to the basin 3 inlet structure, TV examination of pressure pipeline (optional)
The cleaning of the GFK DN 400 pressure pipeline from pumping station 1 to the basin 3 inlet structure with a line length of approximately 195 m and a height difference of approximately 10 m is provided as an option.
_
7 Cleaning sedimentation tanks 1 and 2 as well as sludge dewatering
The subject of the request is the cleaning of sedimentation basins 1 (approx. 2,400 m²) and 2 (approx. 1,900 m²).
The pool slopes are not navigable with construction equipment, which is why work on the embankments must be done manually.
Technological approach of pool cleaning basins 1 and 2:
First, the sludge deposits, approximately 10 to 25 cm thick, deposited on the exposed slopes of the embankment are rinsed off into the interior of the pool with jet pipes.
The removal of existing sludge deposits on the bottom of the pool below the residual water surface (approx. 30 cm thick, difficult to estimate, water depth approx. 1.50 to 1.75 m) is done by using a suitable swimming or amphibious technique.
The wet sludge from tank cleaning, which is to be stacked in storage containers, is to be dewatered with flocculation aids by means of a mobile dewatering system.
With current knowledge, the pool 1 must be cleaned every 2 years and the basin 2 every 3 years.
_
8 Cleaning sedimentation tank 3 and sludge dewatering (optional)
The cleaning of sedimentation basin 3 is provided only as an option, since this basin is exposed to the lowest level of contamination due to the improved water quality.
_
9 Vegetation removal in sedimentation basins 1 to 3
In sedimentation basins 1 to 3, the reed or aquatic plant stock must be mowed after the end of the growing season in autumn (October). Up to now, access from the water side with an amphibious vehicle has proven successful.
_
10 services for recovery/ return/ disposal of cleaned and washed goods/dewatered sludge
Cleaning services involve broaching and washing items as water-sludge mixtures or sludge-water mixtures and dehydrated/conditioned sludge, which must in principle be recycled, reintroduced into plant operation or optionally for disposal.
_
11 Documentation of the work
The documentation of the work must be carried out in such a way that it provides a comprehensible and plausible basis for the acceptance of the services from the client.
Documentation must be prepared for each sub-measure and handed over to the client digitally (by e-mail) and in simple copy in paper form two weeks after completion of the sub-measure.