Monitoring well to assest groundwater condition
Water levels condition and qualities are subject to fluctuations. Groundwater monitoring well are constructed for a regular check of these factors while at the same time ensuring operational factor of the primary production wells. Furthermore, changing seasons can lead to a fluctuation of groundwater levels. It can also happen that several wells are drilled in close proximity to one another which again may lead to interferencing . The quality of an aquifer is also a very important aspect to be measured: it may never be influenced, disturbed or damaged by external circumstances like e.g. disposal sites in the area.
Monitoring well objectives are to determine quantity, quality, and/or environment of groundwater. A monitoring well consists of a small diameter borehole tube that is sealed in the earth with a permeable screen section at the bottom, in an underground reservoir where water is expected to collect. The water will rise and fall in the tube following the groundwater level and allowing level monitoring of groundwater. The groundwater level at that monitoring point will change due to seasonal variations, the effect of precipitation and the result of local water extraction. A level probe, usually, a submersible pressure transmitter will be used for level monitoring and the measured level may be logged over long periods of time to learn how the groundwater level responds to precipitation and extraction of water. The number and location of groundwater monitoring wells should be determined before decisions are made regarding the materials and methods for constructing and installing the wells. A hydrogeological assessment should be the basis for determining the number and location of monitoring wells. According to Indonesian Government act, monitoring well is the well that equipped with monitoring tools to record changes of groundwater condition and environment. (Peraturan Pemerintah Republik Indonesia Nomor 43 Tahun 2008, Pasal 36).
Groundwater monitoring includes
- Measuring and recording the water level;
- Examining physical properties, chemical content, groundwater biology or radioactive elements;
- Recording quantities of groundwater used or commercialized; and/or
- Measuring and recording the groundwater environment change, that is land subsidence.
Monitoring well will observe the impact of production well, thus it is placed near the production well
A distance between production and monitoring well is determined by the local government. Regent/Major, according to each scope of authority, determines monitoring well network based on watershed in a single regency/city area This regulation is also apllied for determination of monitoring well quantity. The total depth of monitoring well depends on a depth of production well. Monitoring well observes the impact of produced aquifers, thus the total depth of it shall be equal to production well, as well as the screen and casing pipe position. Monitoring well is a well that is constructed for observes groundwater level and quality inside specific aquifer. (Keputusan Menteri ESDM, tentang Pendoman Teknis Penyelenggaran Tugas Pemerintahan di Bidang Pengeloiaan Air Bawah Tanah, Bab VI Konservasi, Butir ke-Tiga).
Specification of monitoring well construction is explained on SNI 6469: 2012 about procedures of production well construction with direct circulation. This document explained that “there are three kind of production well, that are shallow, medium and deep with the sequence of preparation, drilling works and reporting. Constructed well production is designed with objectives to be a production or monitoring well”. It shows that there is no difference between production and monitoring well in drilling procedure. The procedure can be seen in our previous method statement/proposal. Specification of monitoring well can be smaller in diameter than the production one, since inside the well shall not be placed the submersible pump. Hence, it is recommended to use 6 inch well casing and 10 inch hole size. The Material of this well can use steel or plastic pipe. The most important tool for monitoring well is Automatic Water Level Recorder (AWLR), that will record and report the water level and condition inside the well automatically, and it able to send the data wirelessly. The tool is mandatory to install in monitoring well
Groundwater monitoring system and management
We assist in the design and implementation of groundwater monitoring systems and management, including the selection and procurement of technology, sensor, and instrumentation. Automatic Water Level Record (AWLR) technology are implemented for continuous monitoring on depth and debit of water. Furthermore, routine sampling and monitoring services are available through experienced field technicians.