Circular No. 32/2011/TT-BTNMT on the technical procedures for monitoring the quality of rainwater

CIRCULAR

Regulations on technical procedures for monitoring
water quality of rainwater 

Pursuant to Decree No. 25/2008/NĐ-CP dated March 4, 2008 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment, amended and supplemented by Decree No. 19/2010/NĐ-CP dated March 8, 2010 and Decree No. 89/2010/NĐ-CP dated August 16, 2010;

Pursuant to the Government Decree No. 102/2008/NĐ-CP, September 15, 2008, on the collection, management, exploitation, and utilization of data on natural resources and the environment;

Pursuant to Decision No. 16/2007/QĐ-TTg dated January 29, 2007 of the Prime Minister approving the overall planning of the national environmental monitoring network until 2020;

Considering the proposal of the Director General of the Vietnam Environment Administration, the Head of the Science and Technology Department, and the Head of the Legal Department,

c) Enterprises may be granted permission for no more than one block out of the total three dual-frequency blocks (FDD) B

PART I
GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates the technical procedures for monitoring environmental water quality of rainwater, including: determining the objectives of monitoring, designing the monitoring program, and implementing the monitoring program.

Article 2. Applicability

1. This Circular applies to the following subjects:

a) State management agencies for the environment at central and local levels; monitoring stations and centers belonging to the national environmental monitoring network and the local environmental monitoring network;

b) Organizations with functions and tasks related to environmental monitoring activities and environmental monitoring service activities for submitting reports and data to state management agencies for the environment at central and local levels;

2. This Circular does not apply to the monitoring of rainwater quality using automatic and continuous devices.

Article 3. Principles for applying standards and methods

1. The application of referenced standards and methods must comply with the monitoring and analysis standards and methods prescribed in Chapter II of this Circular;

2. In case the monitoring and analysis standards and methods prescribed in Chapter II of this Circular are amended, supplemented, or replaced, the new standards and methods shall be applied.

Chapter II
TECHNICAL PROCEDURES FOR MONITORING WATER QUALITY OF RAINWATER

Article 4. Monitoring Objectives

Basic objectives in monitoring the quality of rainwater are:

1. Assessing the quality of rainwater to serve the control of emissions and pollution conditions in regions, localities, areas, and cross-border pollution;

2. Evaluating and monitoring wet deposition of acid over space and time;

3. Assessing the current status and trends in the quality of rainwater;

4. Other requirements for environmental management and protection work.

Article 5. Designing the Monitoring Program

After design, the monitoring program must be approved or accepted in writing by the competent authority or the agency managing the monitoring program. The specific design of the rainwater quality monitoring program is as follows:

1. Type of Monitoring

Based on the monitoring objectives, when designing the monitoring program, it is necessary to determine whether the type of monitoring is background environmental monitoring or impact environmental monitoring.

2. Sampling Location and Position

The sampling points selected must ensure that the collected rainwater samples are representative of the monitored area and meet the program's objectives. Determination of sampling locations and positions is based on the following provisions:

a) Provisions in Section 7 of National Standard TCVN 5997:1995 (equivalent to ISO 5667-8:1993 standard) regarding guidance on collecting rainwater samples;

b) Sampling points may be located at meteorological gardens of meteorological stations, provided that such stations meet the above requirements.

3. Parameters to Monitor

Based on the program's objectives and surrounding pollution sources, monitor the following parameters:

a) On-site measurement and analysis parameters: wind direction, wind speed, temperature, humidity, rainfall amount, solar radiation;

b) Other parameters:

- Mandatory monitoring parameters: pH, electrical conductivity (EC), calcium ions (Ca⁺²), magnesium (Mg⁺²), sodium (Na⁺), potassium (K⁺), ammonia (NH₄⁺), chloride ions (Cl-^-), nitrate ions (NO₃^-), sulfate (SO₄^-2);

- Non-mandatory monitoring parameters: nitrite ions (NO₂^-), fluoride ions (F-^-), bromide ions (Br-^‑), bicarbonate (HCO₃^-), organic acids, phosphate ions (PO₄^3-), heavy metals, aluminum (Al), and organic compounds.

4. Time and Frequency of Monitoring

Rainwater samples are collected according to the following times and frequencies:

a) Rainwater samples are collected during each rain event. In this case, it is necessary to determine the start and end times of the rain event, and the sampler must be present 24 hours a day to collect samples;

b) If it is not possible to collect samples during each rain event, samples can be collected daily (continuously for 24 hours). In this case, the sampling period for one day starts at 8 am and the sample must remain intact (kept cold or preserved with appropriate chemicals);

c) If it is not possible to analyze daily samples, weekly sampling can be conducted by combining daily samples within one week, or continuous collection for one week can be accepted if the samples are kept intact (kept cold or preserved with appropriate chemicals).

5. Monitoring Plan

The monitoring plan is based on the monitoring program and includes the following contents:

a) List of personnel responsible for monitoring and assignment of tasks to each participating staff member;

b) List of organizations and individuals participating and cooperating in environmental monitoring (if any);

c) List of field monitoring equipment, tools, chemicals, and laboratory analysis equipment;

d) Safety equipment and measures to ensure safe labor during environmental monitoring activities;

d) Types of samples to be collected, sample volume, and storage time;

e) Laboratory analysis methods;

g) Budget for implementing environmental monitoring;

h) Plan to ensure quality and quality control in environmental monitoring.

Article 6. Implementation of the monitoring program

The organization and implementation of the monitoring program includes the following tasks:

1. Preparation work

Prior to conducting monitoring, preparatory work must be carried out as follows:

a) Prepare documents, maps, diagrams, and general information about the area where samples will be taken;

b) Monitor weather conditions and weather patterns;

c) Prepare necessary equipment and tools; inspect, clean, and calibrate sampling, measuring, and analytical equipment and tools before going to the field;

d) Prepare chemicals, materials, and tools for sample collection and preservation;

đ) Prepare sample labels, forms, monitoring logs, and analysis records as prescribed;

e) Prepare means of support for sample collection and transportation activities;

g) Prepare safety equipment to ensure workplace safety;

h) Prepare funding and personnel for monitoring;

i) Prepare accommodation facilities for staff working for extended periods;

k) Prepare other relevant documents and forms.

2. Sample Collection, Measurement, and Analysis at the Site

a) Rainwater sampling must comply with the national standard TCVN 5997:1995 (equivalent to the quality standard ISO 5667-8:1993) on rainwater sampling guidelines;

b) In addition to parameters measured and analyzed on-site, pH and EC parameters must be analyzed as soon as possible, either on-site or immediately upon transporting the samples to the laboratory;

c) Quality assurance and control activities at the site shall be conducted in accordance with the guidelines and regulations issued by the Ministry of Natural Resources and Environment regarding quality assurance and control in environmental monitoring.

3. Sample Storage and Transportation

3.1. Rainwater samples, once collected, shall be stored and preserved according to the national standard TCVN 6663-3:2008 (equivalent to the quality standard ISO 5667-3:2003).

3.2. For rainwater samples, attention should be paid to the following:

a) Sample storage

- After measuring pH and EC, filter the sample through a clean membrane filter with a pore size of 0.45 mm, then transfer the sample into a clean container for immediate analysis or store it in a refrigerator at 4°C for no more than 28 days;^°- To prevent biological decomposition processes, one of the following preservatives may be added: chloroform (0.2 ml/100 ml sample) or thymol (40 mg/100 ml);

- Containers for storing samples must be clean and provided by a laboratory that meets the standards.

b) Sample transportation

- Samples must be placed in cold storage boxes and transported to the laboratory along with records of related meteorological parameters;

- Contamination or spillage of samples must be avoided; sample containers must be tightly sealed or wrapped in bags to prevent contamination or loss during transportation;

- If samples are collected daily, they must be transported to the laboratory within 1-2 weeks. If samples are collected weekly, they must be transported to the laboratory within one month.

4. Laboratory Analysis

a) Based on the quality data objectives and laboratory conditions, the analysis of parameters must follow one of the methods specified in Table 1 below:

Table 1. Methods for Analyzing Parameters in the Laboratory

• TCVN 6492:2010;

c) When analyzing rainwater samples, note the following:

- Dilute the sample if the amount of sample is small and the sample contains high concentrations of pollutants exceeding the detection limit. Diluted samples cannot be used to measure pH and EC;

- If the sample is diluted with deionized water, the concentration of ions to be analyzed must also be measured in the deionized water used.

d) Quality assurance and control activities in the laboratory shall be conducted in accordance with the guidelines and regulations issued by the Ministry of Natural Resources and Environment regarding quality assurance and control in environmental monitoring.

5. Data Processing and Reporting

5.1. Data Processing

After completing the analysis of a batch of samples, calculate the ion balance and conductivity to assess the quality of the data. If the calculated ion balance and conductivity ratio deviates from the permissible values, recheck and reanalyze the sample:

a) Anion and cation balance, ratio R

-> Total anions (A), expressed in units of meq/L, calculated using the formula:₁

A = Σ nC

Ai_{(mmol/L) = [Cl-] + [NO}] + 2[SO₃^-- n, [C₄^2-] (1)

Where:

]: is the charge and concentration of ion i (in mmol/L)._{(mmol/L) = [Cl-] + [NO} -> Total cations (C), expressed in units of meq/L, calculated using the formula:

C=Σ nC

(mmol/L)=10_Ci (6-pH)^{+ [Na} ] + [NH⁺] + [K₄⁺] + 2[Mg⁺] + 2[Ca²⁺]: is the charge and concentration of ion i.²⁺] (2)

Where:

]: is the charge and concentration of ion i (in mmol/L)._Ci-> Ratio R

= 100 x (C-A)/(C+A) (3)₁ is calculated according to the following formula:

R₁ The result is accepted when the value of R

falls within the permissible range as shown in Table 2 below:₁ Table 2. Values of R

(C+A),₁ request

->  Conductivity can be calculated using the following formula:₂

(mS/m)= {349.7 x 10

EC_tt + 80.0 x 2[SO^{+ [Na} ] + 71.5[NO₄^2-] + 76.3[Cl₃^-] + 73.5[NH^-] + 50.1[Na₄⁺] + 73.5[K⁺] + 59.8 x 2[Ca⁺] + 53.3 x 2[Mg²⁺- [ ]: is the concentration of ions, in mmol/L;²⁺]}/1000 (4)

Where:

- Coefficients preceding ion concentrations: are the specific conductivities of those ions, in S.cm

/mol at 25²->  Ratio R^°C.

is calculated as follows:₂ = 100 x (EC

R₂ -EC_tt dđ_)/(EC+ EC_tt - EC_)/(EC) (5)

Where:

: is the conductivity;_tt: is the conductivity measured by a meter at 25

: is the conductivity;_)/(ECfalls within the permissible range as shown in Table 3 below:^°C.

falls within the permissible range as shown in Table 2 below:₂ Table 3. Values of R

(mS/m)₂ request

>0, the presence of bicarbonate ions (HCO₁) must be considered in the values of R , R₃^-. The concentration of HCO₁is calculated using the formula:₂[HCO₃^- ] = [H

] x K₃^-a1₂Add distilled water to make up to 1 liter of solution.₃/ [H_{: is the first dissociation constant of carbonic acid.}The concentration of CO⁺] (6)

Where:

- K_{: is the first dissociation constant of carbonic acid.}in air is 360 ppm, K

, thus we have:₂ ] x 10_{: is the first dissociation constant of carbonic acid.} = 10^-6.35(pH-6.35)

] x K₃^-a1₂Add distilled water to make up to 1 liter of solution.₃= 1.24 x 10^(pH-5.35) - Comment on the data: comments on the data must be based on the results of monitoring, analysis, verification, and relevant technical standards and specifications.^{5.2. Reporting Results} (7)

- Commenting on data: comments on data must be based on the results of observed measurements, processed analyses, verified checks, and relevant technical standards and specifications.

5.2. Reporting Results

After completing the monitoring program, the monitoring results report must be prepared and submitted to the competent state agency as prescribed.

Chapter III
IMPLEMENTATION

Article 7. Implementation Organization

1. The General Department of Environment shall be responsible for guiding, inspecting, and supervising the implementation of this Circular.

2. The Minister, the Heads of ministerial-level agencies, the Heads of government-affiliated agencies, the Chairpersons of People's Committees at all levels, and organizations and individuals related to this matter shall be responsible for implementing this Circular.

Article 8. Effective Date

1. This Circular takes effect from September 15, 2011.

2. During the implementation of this Circular, if there are difficulties or obstacles, the relevant agencies, organizations, and individuals are requested to reflect them to the Ministry of Natural Resources and Environment (through the General Department of Environment) for timely consideration and resolution./.