WELL SERVICES, well works, wells, water analysis

The well services offered by ATE CR, a.s. include the location of a groundwater source within the site by a hydrogeologist, through the implementation of exploratory boreholes with a drilling diameter of 178-280 mm and fittings (well strainers) with the diameter of 125-200 mm, with a certificate of drinking water , backfill and cementation.

We also offer construction work regarding the borehole drilled for wells according to ČSN 75 5115, pump fitting, connection to the house water system, processing of the necessary documentation for a negotiations with authorities, and the final permission for use. The basic aim of our efforts is to guarantee a well with the water quantity and quality desired by the customer!

WELL SERVICES, SEARCH FOR GROUNDWATER SOURCES

Designing, well services

Before actually seeking for sources of groundwater within the client’s site and before we start designing work, we search for the necessary information regarding the location from maps and archives.

Field reconnaissance and borehole locating

The field reconnaissance and borehole locating are necessary to get the hydrogeologist introduced to the terrain, and the expert search for an ideal location of the borehole (well) according to ČSN 75 5115. We are able to complete the site assessment within 1 following the inquiry. If a new building is planned, it is best to first find an ideal location for a well, and then set the position of the building accordingly.

Recommendation: We recommend having a well ready before you start building your house. This has two advantages:

• You avoid the risk of having your house and building site damaged by the drilling equipment used (the access to the site for the technology is not complicated)
• Independent source of water for the construction process

Notification of exploratory borehole to authorities

At least 15 days before the commencement of the drilling work, it is necessary to notify the relevant local authorities. If an exploratory borehole deeper than 30 metres is made, the project needs to be submitted to the relevant Regional Office, 30 days prior to the implementation.

WELLS - OVERALL IMPLEMENTATION OF EXPLORATORY BOREHOLES

Well services - exploratory boreholes

We choose the best drilling technology based on the expected geological situation. The borehole depth, the fitting and drilling equipment diameter depend on the purpose of the well specified by the customer. Most frequent well drilling diameters and fitting diameters, depending on the purpose of the drilled well:

• Bore diameter 178 mm / fitting diameter 125 mm - ideal for small cottages without permanent residents, and for watering a small piece of land.
• Bore diameter 203 mm / fitting diameter 140 mm - ideal for bigger cottages and small family homes with all-year-round residents, and for watering standard pieces of land.
• Bore diameter 254 mm / fitting diameter 160 mm - ideal for standard family homes with all-year-round residents, and for watering larger pieces of land.
• Bore diameter 280 mm / fitting diameter 200 mm - ideal for larger compounds, farms with livestock production, field irrigation, etc.

Fitting - the filter is composed of PVC-U or PE-HD; for wells and always with a certificate for drinking water. Perforated within the water-bearing sections.  The annular space between the fittings and the bore wall is backfilled with washed waterwork pebble gravel. In the upper part of the borehole, the fitting is full-scale. As regards shallow quaternary collectors, the annular space between the fittings and the bore wall is sealed with impermeable clay (bentonite) in order to protect the water source from surface contamination.

Work coordination and geological documentation

During the entire implementation period, all well services are subject to professional management, monitoring and coordination by the responsible hydrogeologist. In addition, the rock structure within the borehole and the presence of aquifers are documented on a continuous basis. The documentation is essential for the proper borehole fitting.

Borehole clearing and hydrodynamic tests

After the borehole is fitted with the necessary equipment, the water in the well is deprived of thick sludge and coarse impurities, with the use of a suitable pump. After cleaning, we perform hydrodynamic tests consisting of pumping and recovery testing. Water is pumped using submersible pumps with an adjustable output, usually between 0.2 and 1.0 l/s. The tests help us to determine the useful yield of the source, and the influence of the water collection from the well on the surrounding water sources. Based on the results we set conditions for the collection of groundwater from the well. The duration of the hydrodynamic testing is chosen depending on the purpose of the well, and on the local natural conditions.

Water sampling and analysing

Towards the end of a pumping test, usually after sufficient cleaning and removal of mechanical impurities, a water sample will be taken into a sample container, most usually for the so-called “Reduced Drinking Water Analysis” in accordance with Ministry of Health Decree No. 252/2004 Coll., which establishes sanitary requirements for drinking and hot water and the frequency and scope of drinking water. Water analyses are carried out by accredited laboratories.

Report (hydrogeological assessment, well project)

The Report includes written and graphic summary of all the tasks specified above, including a hydrogeological report with a round seal of a hydrogeologist and a project for the conversion of an exploratory borehole to a tube (drilled) well with a round seal of an authorized engineer for water-management structures, in accordance with the requirements of water-management authorities.

CONVERSION OF A BOREHOLE TO A WELL ACCORDING TO ČSN 75 5115

The conversion of a borehole to a tube well in accordance with the current legislation consists of an excavation pit around the borehole, to the depth of 1.5 m below the ground level, concreting of the bottom, shortening of the well strainer, placing of concrete rings, fitting of the borehole with pumping equipment and the connection thereof to the water supply system.

Wells - excavation and concrete work

A hole is excavated around the borehole equipment so that it is possible to safely place concrete rings to the depth of about 1.5m, including the surrounding clay seal. The borehole equipment is reduced to the height of approximately 30 cm from the pit bottom. The pit bottom is concreted and provided with a protective casing over the borehole fitting.

Placing of concrete rings and levelling

Concrete rings are placed in such pits (with the internal diameter of 800 mm or 1000 mm, as requested), ended 0.5 meters above the ground. From outside the rings, the space from the pit bottom to the ground level is sealed with clay, while the rest of the pit is backfilled with the excavated material. Excess excavated soil is removed, or used for levelling within the site. The surface is then levelled and finalized. The rings are covered with an overlapping split concrete deck.

Borehole fittings (pumps, pipes, water level sensors)

The borehole (well) is fitted with a suitable pump, depending on the borehole depth and the water yield. The water collection mode and the maximum decrease of the groundwater level are monitored with water level sensors. The pipeline leads through the side of the rings to a ditch, at a non-freezing depth, where it is connected to the line leading to the house water supply system.

Domestic water supply system, raw water treatment plant, well connection

Domestic water supply systems consist of a pressure tank (of the required size), and equipment for the treatment of raw water which will then be used as drinking water. The domestic water supply system is connected with the well through pipeline leading at a non-freezing depth in the shortest possible way.

NEGOTIATIONS WITH AUTHORITIES

The scope of negotiations with authorities includes the provision of a planning permission, building permit, water-management decision and the final approval for use. In terms of time, usually about 2-3 months are required following the commencement of the planning permission proceedings.

Planning permission

The first step towards legalizing a well is obtaining a planning permission regarding the location of a structure (well). On the basis of the planning permission, it is possible to proceed with the following steps.

Building permit

A building permit to convert an exploratory borehole to a well according to Act No. 254/2001 Coll. (Building Act) is issued by the water-management authority on the basis of an approved project and a round seal attached by a person authorized for water-management structures.

Water-management decisions

A water-management decision (use of groundwater = collection permit) is issued by the water-management authority on the basis of a hydrogeological report, issued by a person authorized in the field of hydrogeology.

Final approval of well use

After the work (well) is completed and all the requirements of the competent authorities are fulfilled, it is possible to apply for a final approval for use, or notify the use of the water work.

EXAMPLES OF COMPLETED WELLS, WELL SERVICES

Construction of a well according to the standard of ATE CR, a.s., including the price

As an example, we would like to present a  well completed in 2009 in the village of Doubravčice, district of Kolín. The well depth is 30 metres. The well is fitted with PVC-U well strainers (with a drinking water certificate), with a diameter of 160 mm. The well is ready for final approval for use. The total cost of the work (well) was CZK 120 000, excl. of VAT. More...