Key points of technical specifications for groundwater quality monitoring
1、 Standard layout of monitoring points
Principles of deployment
Representativeness: Monitoring points need to cover different hydrogeological units, reflecting regional groundwater quality and spatial changes.
Continuity: Prioritize the use of existing civilian wells, production wells, or spring points to maintain long-term stability of monitoring data.
Key monitoring: Increase the number of monitoring points for water supply aquifers, surrounding pollution sources, groundwater funnel areas, and areas with special hydrogeological problems.
Dynamic adjustment: Evaluate the operation status of the monitoring network every 5 years and optimize points based on changes in pollution sources, development activities, etc.
Deployment requirements
Regional monitoring: Distribution points along the direction of groundwater flow and vertical direction, with controlled monitoring points covering recharge, runoff, and discharge areas.
Drinking water source area: Focusing on the mining layer, when there are multiple aquifers, it is necessary to monitor the aquifers that have hydraulic connections with the target layer.
Surrounding pollution sources:
Industrial agglomeration zone: One control point is set up upstream, and three or more diffusion monitoring points are set up vertically downstream, with one on each side.
Tailings pond and hazardous waste disposal site: upstream, both sides, and downstream points are arranged to assess pollution dispersion.
Special geological areas: tracking the entrances and exits of underground rivers in karst areas, setting up connected fracture networks in fracture areas, and increasing the distribution of potential pollution sources.
2、 Sampling and Preservation Technical Specifications
Sampling frequency
Background value monitoring well: Sample once a year during the dry season.
Pollution control monitoring well: Sampling once a month (6 times a year). If a certain project is below 1/5 of the control value for two consecutive years and there are no new pollution sources, it can be adjusted to once during the dry season.
Drinking water source monitoring well: Sampling once a month.
Emergency monitoring: Increase the frequency of pollution accidents or special circumstances at any time.
sampling method
Preparation before sampling: Develop a plan (purpose, location, project, time, route, personnel division, quality assurance measures).
Sampling equipment: Use specialized samplers to avoid cross contamination.
On site monitoring: Simultaneously measure indicators such as pH, conductivity, dissolved oxygen, etc.
Sample preservation
Storage conditions: Select refrigeration (4 ℃), add fixative, or store in the dark according to the testing items.
Transportation requirements: Delivery to the laboratory within 24 hours, protected from vibration, high temperature, or direct sunlight.
3、 Monitoring projects and analysis methods
Routine monitoring items
Physical indicators: chromaticity, odor and taste, turbidity, visible substances to the naked eye.
Chemical indicators: pH, total hardness, total dissolved solids, sulfate, chloride, iron, manganese, ammonia nitrogen, nitrate, nitrite, permanganate index.
Microbial indicators: total coliform bacteria and total bacterial count.
Radioactive indicators: total alpha radioactivity, total beta radioactivity.
Characteristic pollutant monitoring
Industrial pollution areas: Add heavy metals (mercury, arsenic, cadmium, chromium, lead), organic compounds (benzene derivatives, halogenated hydrocarbons), etc. according to industry types.
Agricultural area: Monitor pesticide residues (BHC, DDT) and fertilizer related indicators (nitrogen, phosphorus).