HJ 25.5-2018Technical Guideline for Verification of Risk Control and Soil Remediation of Contaminated Site (English PDF)

4.1 Basic principles

Risk management and pollution assessment of contaminated land should assess whether the soil has reached the repair target and whether the risk control is achieved Scientific and systematic assessment of the requirements, whether the land risk has reached an acceptable level, etc.

It is recommended to provide a scientific basis for the management of contaminated land.

4.2 Work content

The work of risk management and soil remediation evaluation of contaminated land includes. updating the conceptual model of the plot and sampling the site and laboratory testing, risk management and repair effectiveness evaluation, proposed late environmental monitoring recommendations, preparation of effect evaluation report.

4.3 Working procedures

4.3.1 Updating the plot concept model

The concept model of the plot should be updated in real time according to the risk management and repair progress and the mastery information.

The basis for the effectiveness evaluation layout scheme is provided.

4.3.2 Spot sampling and laboratory testing

The layout scheme includes the object and range of the effect evaluation, the sampling node, the sampling period and frequency, the number and location of the distribution points, Detect indicators and other content, and explain the basis for the above content determination. In principle, the risk management and repair implementation plan should be prepared.

The preliminary layout plan for the evaluation of the segment preparation effect, and before the development of the site risk management and repair effect evaluation, according to the update the post conceptual model is refined and updated.

According to the layout plan, develop sampling plans, determine test indicators and laboratory analysis methods, and conduct on-site sampling and experimentation.

Room testing, clear on-site and laboratory quality assurance and quality control requirements.

4.3.3 Risk management and soil remediation evaluation

According to the test results, assess whether the soil remediation meets the repair target or acceptable level, and assess whether the risk control is achieved.

Required requirements.

For soil remediation effects, one-by-one comparison and statistical analysis can be used to evaluate the results.

According to the situation, put forward the post environmental supervision recommendations and prepare the repair effect evaluation report. If the repair effect is not achieved, it should be supplemented.

Charge repair.

For risk management and control effects, if the engineering performance indicators and pollutant indicators meet the evaluation criteria, then the risk management is judged.

If the expected results are achieved, the operation and maintenance can be continued; if the engineering performance indicators or pollutant indicators do not meet the evaluation criteria, then If it is judged that the risk management and control has not achieved the expected results, the risk management and control measures must be optimized or adjusted.

4.3.4 Proposing late environmental supervision recommendations

According to the implementation situation and effect evaluation conclusions of the risk management and repair project, the environmental supervision recommendations were put forward.

4.3.5 Compilation effect evaluation report

3 Summarize the above work and prepare an effect evaluation report. The report should include the risk management and repair project overview and environmental protection.

Implementation of protective measures, evaluation of distribution points and sampling, analysis of test results, conclusions of effect evaluation and recommendations for environmental supervision in the later period and so on.

The working procedures for risk management and soil remediation evaluation of contaminated plots are shown in Figure 1.

Figure 1 Work procedure for risk management and soil remediation evaluation of contaminated land

5.1 General requirements

The effect evaluation agency shall collect relevant information on the risk management and repair of the land parcel, carry out on-site reconnaissance work, and pass the land parcel Responsible person, construction person in charge, supervision personnel, etc. to communicate and interview, understand the conclusions of the land survey and evaluation, risk management and repair Implementation of complex projects, implementation of environmental protection measures, etc., mastering geological and hydrogeological conditions of land masses, spatial distribution of pollutants Key information such as cloth, contaminated soil destination, risk management and repair facility setup, risk management and repair process monitoring data, etc.

Update the plot conceptual model.

45.2 Data Review

5.2.1 Data review list

5.2.1.1 Before the impact assessment work is carried out, relevant information on risk management and restoration of contaminated land parcels should be collected.

5.2.1.2 The data list mainly includes plot environmental investigation report, risk assessment report, risk management and repair plan, and engineering.

Implementation plan, engineering design data, construction organization design data, engineering environmental impact assessment and its approval, construction and operation in-process monitoring data, supervision reports and related materials, project completion reports, implementation plan change agreements, transportation and reception Discussion and records, construction management documents, etc.

5.2.2 Data review points

5.2.2.1 The main points of the review of the data include the overview of the risk management and repair project and the implementation of environmental protection measures.

5.2.2.2 Risk management and repair project overview review mainly through risk management and repair programs, implementation plans, and risks Other documents in the process of control and repair, understand the scope of repair, targets, repair engineering design, repair engineering construction, Repair start time, transportation records, operation monitoring data, etc., to understand the specific situation of risk management and repair project implementation.

5.2.2.3 Review of the implementation of environmental protection measures mainly through data on prevention and control of secondary pollution in the process of risk management and repair, the data and reports are sorted out to analyze the secondary pollution of soil and groundwater that may be caused by risk management and repair works.

5.3 Site survey

5.3.1 On-site reconnaissance work should be carried out to understand the situation of risk management and restoration of contaminated land and the implementation of environmental protection measures.

Conditions, including the operation of the repairing facilities, the progress of the repairing works, the cleaning of the foundation pits, the temporary storage and transportation of contaminated soil, Temporary road use in the plot, repair construction management, etc.

5.3.2 Investigators may record on-site surveys by means of photos, videos, audio recordings, texts, etc.

5.4 Personnel interview

5.4.1 Personnel interview work should be carried out to carry out the situation of land risk management and restoration and the implementation of environmental protection measures.

A comprehensive understanding of.

5.4.2 Interviewees include land plot responsible units, plot survey units, plot repair plan preparation units, supervision units, repairs Participating personnel of units such as re-construction units.

5.5 Update plot concept model

5.5.1 On the basis of data review, on-site reconnaissance, and personnel interviews, master the situation of land risk management and restoration, and conclude Geological and hydrogeological conditions of the combined land, spatial distribution of pollutants, characteristics of restoration techniques, layout of restoration facilities, etc.

The model is updated to improve the conceptual model of the implementation and control of land risk management and restoration.

5.5.2 The concept model of a parcel generally includes the following information.

a) Overview of site risk management and restoration. repair start time, repair scope, repair target, repair facility design Number, repair process operation monitoring data, technical adjustment and operation optimization, wastewater and exhaust emissions during the repair process According to the amount of drug added, etc.;

b) Focus on pollutants. original concentration of target pollutants, concentration changes during operation, potential secondary pollutants and the production of intermediate products, the excavation and transportation of pollution sources of soil ectopic relief sites, the removal rate of repair technology, Changes in the spatial distribution characteristics of pollutants, as well as potential secondary pollution areas;

c) Geological and hydrogeological conditions. focus on geological and hydrogeological conditions of the site, and geology before and after the restoration of the facility and changes in hydrogeological conditions, changes in soil physical and chemical properties, etc., whether there is a preferential flow path in the operation process;

5d) Potential Receptors and Surroundings. Combining land use planning and building structure design data, analysis and repair engineering the relative positional relationship between the contaminating medium and the receptor after the end, and the key exposure pathway of the receptor.

5.5.3 The concept model of the plot can be expressed in the form of words, diagrams, tables, etc., as the scope of the evaluation effect, sampling nodes, cloth the basis of point location, etc.

5.5.4 The conceptual model of the plot involves information and its effects are shown in Appendix A.

6 Spot sampling and laboratory testing

6.1 Evaluation of soil remediation effect

6.1.1 Evaluation of foundation pit cleaning effect

6.1.1.1 Evaluation object the evaluation object of the foundation pit cleaning effect is the foundation pit determined in the land repairing plan.

6.1.1.2 Sampling node

6.1.1.2.1 The bottom and side walls of the foundation pit left after the contaminated soil is cleaned shall be sampled after the foundation pit is cleaned and before backfilling.

6.1.1.2.2 If the foundation wall of the foundation pit is to be used, it is advisable to carry out the sampling of the side wall of the foundation pit at the same time as the foundation pit cleaning, or in the foundation enclosure.

After implementation, sample at the outer edge of the enclosure.

6.1.1.2.3 The foundation pits may be sampled in batches according to the progress of the project.

6.1.1.3 Number and location of distribution points

6.1.1.3.1 The minimum number of sampling points recommended for the bottom and side walls of the foundation pit is shown in Table 1.

6.1.1.3.2 The bottom of the foundation pit adopts the system layout method, and the sidewall of the foundation pit adopts the equidistant layout method. See Figure 2 for the location of the layout.

6.1.1.3.3 When the depth of the foundation pit is greater than 1 m, the side wall shall be vertically stratified, and the properties of the soil layer and the pollution shall be considered.

To the distribution feature, the sampling point is set at the position where the pollutant is easily enriched, and the vertical distance between the sampling points of each layer is not more than 3m, determined according to the actual situation.

6.1.1.3.4 The sample of the bottom and side walls of the foundation pit is mainly composed of soil surface layer after removing impurities (0~20cm), and does not exclude deep layers.

sampling.

6.1.1.3.5 For heavy metals and semi-volatile organic compounds, a mixed sample can be collected in a sampling grid and interval, and the sampling method refer to HJ 25.2 for implementation.

Table 1 Recommended minimum number of sampling points at the bottom and side walls of the pit

Foundation pit area

Number of sampling points at the bottom of the pit Number of sidewall sampling points x12500 Grid size does not exceed 40m×40m. The sampling point interval does not exceed 40m.

6(1) bottom of foundation pit--system layout method (2) sidewall of foundation pit--equal distance layout method

Figure 2 Schematic diagram of the bottom and side wall of the foundation pit

6.1.2 Evaluation of soil ectopic repair effect

6.1.2.1 Evaluation object the object of soil effect evaluation after ectopic repair is the soil pile after ectopic repair.

6.1.2.2 Sampling node

6.1.2.2.1 Soil after ectopic repair should be sampled after repair is completed and before reuse.

6.1.2.2.2 Soils that have been ectopically repaired in a heap mode should be sampled prior to removal of the heap.

6.1.2.2.3 Soil piles after ectopic repair can be sampled in batches according to the progress of repair.

6.1.2.3 Number and location of distribution points

6.1.2.3.1 After repairing the soil, in principle, each sampling unit (the amount of earthwork represented by each sample) should not exceed 500 m3;

Calculate the repair coefficient based on the characteristic parameters of the pollutant concentration distribution in the soil after repair, according to different coefficient of variation the query calculates the corresponding recommended number of samples (see Table 2), and the calculation method of the differential coefficient is shown in Appendix B.

6.1.2.3.2 For batch-repaired repair techniques, at least one sample per lot is taken while meeting the above requirements.

6.1.2.3.3 For the repair technology treated in the stack mode, if the sample is taken before the pile is removed, the above requirements are met, the sampling points should be set in conjunction with the size of the heap. See Table 3 for recommended quantities.

6.1.2.3.4 After the restoration, the soil is generally set by the system layout method; at the same time, the spatial difference of the repair effect should be considered.

Adding sampling points to the weak area of the complex effect. Heavy metals and semi-volatile organic compounds can be collected in a sampling unit.

The sampling method is performed with reference to HJ 25.2.

6.1.2.3.5 The height of the soil pile after repair shall be convenient for the evaluation of the repair effect.

Table 2 Number of minimum sampling points of soil after restoration

Differential coefficient Sampling unit size M3 0.05~0.20 100 0.20~0.40 300 0.40~0.60 500 0.60~0.80 800 0.80~1.00 1000

7 Table 3 Number of minimum sampling points of soil after restoration of heap mode Volume of the heap M3 Number of sampling units