In order to implement the relevant requirements of the Central Ecological Protection Inspector “Review” feedback rectification plan, guide the establishment of the chemical industry enterprise gathering area, chemical enterprises and surrounding groundwater quality monitoring wells and groundwater quality monitoring work, and formulate this guidance.

First, the basis of legal standards

(1) Article 40 of the Law of the People's Republic of China on Prevention and Control of Water Pollution

(II) Technical Guidelines for Environmental Impact Assessment Groundwater Environment (HJ 610-2016)

(III) Technical Specifications for Groundwater Environmental Monitoring (HJ/T 164-2004)

(4) "Technical Specifications for Groundwater Monitoring Engineering" (GB/T 51040-2014)

(V) "Code for the Construction of Groundwater Monitoring Wells" (DZ/T 0270-2014)

(6) "Code for geological drilling of hydrological wells" (DZ/T 0148-2014)

(VII) "Guidelines for the Investigation and Evaluation of Groundwater Environmental Conditions" (Circular Office [2014] No. 99)

Second, the establishment of groundwater quality monitoring wells

In order to monitor the first layer of groundwater, take into account sensitive targets such as surrounding drinking water sources, control the changes in groundwater environmental quality, and monitor the groundwater pollution of enterprises, in accordance with the principles of “source control, zone prevention and control, pollution monitoring, and emergency response”. Hydrogeological conditions and characteristics of construction projects Set up chemical industry enterprise gathering areas, chemical enterprises and surrounding groundwater quality monitoring wells.

According to regional hydrogeological conditions, groundwater quality monitoring wells are established in the following two types of areas:

Class A: Yellow River alluvial plain with stable aquifer, relatively slow seepage, downstream of piedmont alluvial fan and weathered fissure water.

Class B: no stable aquifer, karst fissure water with relatively fast seepage, tectonic fissure water area and upper middle and upper part of piedmont alluvial fan.

The distance between the monitoring well and the boundary of the chemical enterprise gathering area or the boundary of the chemical enterprise is not more than 1 km in principle in the Class A area, and not more than 2 km in principle in the Class B area.

(1) Chemical enterprises gathering areas. According to the requirements of laws and regulations, combined with local hydrogeological conditions, and timely reflection of changes in regional groundwater quality, the number of monitoring wells is determined. The total number of monitoring wells is not less than 5 eyes in principle.

1. Establishment of Class A regional monitoring wells. 1 monitoring well is set up in the area of 1.0-1.5 square kilometers; 1 background monitoring well is set up, and the groundwater flow is arranged upstream in the gathering area; 2 holes in the pollution diffusion well, perpendicular to the groundwater flow direction as close as possible to the gathering area on both sides of the gathering area At the boundary, no less than one eye is deployed; the pollution monitoring well is not less than two eyes, and the groundwater flowing in the gathering area flows downstream.

2. Establishment of Class B regional monitoring wells. One monitoring well is set up every 1.5-2.0 square kilometers. No less than 3 monitoring wells are installed on the main runoff zone of the groundwater. The background monitoring wells are arranged on the upstream main runoff zone of the gathering area. The pollution monitoring wells are arranged in the gathering area and downstream main runoff zones. In 1 eye.

(2) Chemical enterprises. In accordance with the requirements of the Technical Guidelines for Environmental Impact Assessment (Groundwater Environment) (HJ 610-2016), combined with the local groundwater hydrogeological conditions, the establishment of groundwater quality monitoring wells was carried out.

1. Establishment of a Class A site monitoring well.

(1) Sites with groundwater environmental impact assessment level 1 or 2 or groundwater hydrogeological conditions meeting the requirements of primary and secondary environmental impact assessment, the establishment of monitoring wells shall generally be no less than 3 eyes, and shall be at least at the construction project site. One eye is set up on the upstream and downstream of the main runoff zone of the groundwater. Among them, the environmental impact assessment is a first-level construction project. Based on the general plan layout of the construction project, combined with the environmental impact assessment conclusions and emergency response time requirements, additional monitoring points should be added to the key pollution risk sources.

(2) The groundwater environmental impact assessment level is a three-level construction project or the groundwater hydrogeological condition meets the requirements of the third-level environmental impact assessment. The monitoring well should be set at least one eye downstream of the groundwater main runoff zone of the construction project site.

2. Groundwater quality monitoring wells in Class B areas are, in principle, established with reference to Class A requirements. In the bedrock mountain areas where the monitoring wells are difficult to arrange, the groundwater environmental impact assessment level is one or two. The construction project has at least 1-2 groundwater quality monitoring wells, and the third-level construction project determines the groundwater according to the actual conditions. The number of quality monitoring wells.

(3) Others.

1. In chemical industry gathering areas or chemical enterprise sites, if the downstream groundwater main runoff is distributed with sensitive targets such as drinking water sources, one monitoring well should be set up 1 km downstream of the site boundary.

2. For chemical enterprises in chemical industry gathering areas, where there are provisions in national laws and regulations or administrative licenses of relevant departments, monitoring wells shall be set up in the downstream of chemical industry enterprises' boundary and key pollution risk sources in accordance with relevant regulations and requirements. The monitoring wells should be balanced with each other as much as possible to minimize the number of monitoring wells. If the conditions for the establishment of groundwater quality monitoring are not met, soil monitoring may be carried out with the consent of the local ecological environment department.

3. Identify the basic functions of the monitoring well, such as background value monitoring wells, groundwater environmental impact tracking and monitoring wells, and pollution diffusion monitoring wells.

3. Groundwater quality monitoring well depth and civil engineering and drilling requirements

(1) Monitoring the depth of the well.

In the category A area, the groundwater quality monitoring well is based on the principle of monitoring the first aquifer and does not penetrate the first aquifer. Relevant requirements for the implementation of the "Code for the Construction of Groundwater Monitoring Wells" (DZ/T 0270-2014).

In the B-type area, the well depth of the groundwater quality monitoring well should meet 30 meters below the lowest groundwater level in the past three years.

(2) Monitoring wells and civil works. The civil engineering construction of new groundwater quality monitoring well structure, well pipe material, well construction and water stop should implement the requirements of “Code for Construction of Groundwater Monitoring Wells” (DZ/T 0270—2014). The wall pipe should be higher than the ground near the monitoring well. - 0.5 m, reserve groundwater level monitoring port (hole), and do well monitoring wellhead (hole) protection.

(3) Monitoring well drilling. The construction of the monitoring well must have a complete geological catalogue and “swelling” information, and “one well and one file” to establish the “well” file.

Groundwater quality monitoring wells shall be drilled in accordance with the requirements of the Hydrological Wells Geological Drilling Regulations (DZ/T 0148-2014) to ensure the quality of the monitoring wells. The construction of the monitoring well must have a complete “well-forming” process.

Fourth, monitoring projects, frequency and data reporting

(1) Monitoring projects. Monitoring projects include conventional factors and characteristic pollution factors. The conventional factors are the groundwater quality routine indicators (except radioactive indicators, microbial indicators, etc.) in Table 1 of the Groundwater Environmental Quality Standard (GB/T 14848-2017). The characteristic pollution factor should be determined on the premise of comprehensively analyzing the groundwater historical monitoring data in the agglomeration area and accurately grasping the status of the sewage discharge of the enterprise and the composition of the solid waste leachate, which may cause groundwater pollution. The characteristic pollution factor should be dynamically adjusted according to the monitoring results and the changes in the discharge of pollutants in the agglomeration area.

At each sampling and monitoring, the groundwater level should be recorded at the same time and submitted as monitoring data.

(2) Frequency of monitoring.

1. The monitoring frequency of conventional factors is not less than 2 times per year, and is monitored in the dry season (May-June) and the wet season (August-September).

2. The monitoring frequency of groundwater characteristic pollution factors in light pollution and medium pollution chemical enterprises gathering areas and chemical enterprises shall not be less than 3 times per year, respectively in the annual wet season (8-September) and the flat water period (December-January). Monitoring during the dry season (May-June).

3. The frequency of monitoring the pollution factor of the groundwater in heavy pollution gathering areas and chemical enterprises is not less than once per quarter. They are monitored during the annual wet season (August-September), the flat water period (December-January), the dry season (May-June) and others (February-March).

The frequency of monitoring can be adjusted according to changes in groundwater quality. In the event of an accident, the frequency of the monitoring is encrypted according to the emergency plan.

(3) Monitoring projects and monitoring frequency adjustments. After conducting two natural year water quality monitoring, if the routine monitoring project is stable or the water quality is stable, the frequency of monitoring can be reduced. The order of frequency reduction is other (2-March) and flat water period (December-January).

(4) Data submission. The monitoring data and evaluation report shall be reported to the local ecological environment department for record within 10 days after the end of the monitoring work.

V. Responsible subject

The administrative department of chemical enterprises and the chemical enterprises shall be responsible for the establishment, construction, maintenance, water quality monitoring and data reporting of groundwater quality monitoring wells; after the monitoring wells are abandoned, the sealing work shall be carried out in accordance with relevant requirements.

6. Groundwater quality monitoring well acceptance

The layout, construction and drilling of groundwater quality monitoring wells shall be carried out by the responsible entity to organize and ensure the compliance with the relevant national norms. The responsible entity shall organize the acceptance and organize the well files according to the requirements of “one well and one file”. The local ecological and environmental departments should strengthen supervision, organize the guidance work for the construction of monitoring wells, and conduct random inspections of the monitored monitoring wells. The proportion of random inspections shall not be less than 30%.