Setting tolerance limits for discharge of
wastewater or effluent on land for
agriculture purposes
Dr. R.M.S.K Rathnayake
Deputy Director General ( Environment Protection)
Central Environmental Authority

WEPA International Workshop
atTokyo, Japan
1

Content
1. Introduction
2. Soil Pollution and related Incidents
3. Legal background & enforcement
4. Reviewing & Setting tolerance limits
5. Issues in implementation
6. Way forward1. Introduction
Sri Lanka is rich in natural resources such as flora, fauna,water & high Diversity of Soil.
Major soil types include ;
•
•
•
•
•

Reddish Brown Latosolic Soils
Latosols and Regosols on Old Red and Yellow Sands
Red yellow Pod soils
Immature Brown Loams
Bog & half bog Soils

Soil Map of Sri Lanka

Source‐ Land Use division ‐Irrigation Department, Sri Lanka

Different Types of Aquifers in Sri Lanka( Panabokke and Perera 2005)

5

Main types of groundwater aquifers in Sri Lanka
1. Shallow Karstic Aquifer of Jaffna Peninsula
2. Deep Confined Aquifers
3. Coastal Sand Aquifers
4. Alluvial Aquifers
5. Shallow Regolith Aquifer of the Hard Rock Region
6. South Western Lateritic (Cabook) Aquifer

No of Tube wells constructed by Water Resource Board andNational Water Supply & Drainage Board

9

Issues on Ground Water• Depletion of the ground water table– Climate change issues– Decrease of recharging• Pollution issues– Industrial– Domestic– Agriculture– Solid and hazardous wastes

2. Soil Pollution & related incidents
The main anthropogenic sources of soil pollution

Wastewater & solid waste consist of ;Industrial waste & wastewater
domestic waste, livestock and municipal wastes
Agrochemicals
petroleum‐derived products

New concerns are being raised about emerging pollutants






Pharmaceuticals
endocrine disruptors
hormones and toxins
biological pollutants ‐micropollutants in soils (bacteria and viruses)
Microplastics

soil pollution can severely degrade the major ecosystem services provided by soil

1) Chunnakam/Jaffna groundwater contamination by oil (2015)
The well water was polluted in Chunnakam, Jaffna from 03 power plants have createdproblems for well water uses in the area. The studies carried out in 82 wells indicated that
44 wells were exceeding the limit of SLS 614: 2013, specifications for potable water for oil& grease ( 0.2 mg/l) while 13 wells were greater than the oil & grease detection level(2mg/l)Finally it was proven that due to long term disposal of oil contaminated waste, the wells in
the area were polluted

Analytical Results
pH

TEMP
oC

COD
mg/l

Oil &
Greasemg/l

Sulphate
mg/l

NO‐3 as N
mg/l

PO4‐3 as P
mg/l

Total
Hardness
mg/l

APHA,
2130 B

APHA,
2550 B

APHA,
5220 –B

APHA,
5520 B

AHPA
4500‐E

AHPA
418 D

AHPA
4500 P E

AHPA
2340‐CEC
TURB
mS/cm NTU

Test
methodReference No
142/15/LS
143/15/LS
144/15/LS
145/15/LS
146/15/LS
147/15/LS
148/15/LS
149/15/LS
150/15/LS
151/15/LS
152/15/LS
153/15/LS
154/15/LS
155/15/LS
156/15/LS
157/15/LS
158/15/LS
159/15/LS
160/15/LS
161/15/LS
Sri Lanka Standard
614:2013
Requirement(max)

APHA,
APHA,
+
4500 ‐H B 2510 B

7.4
7.5
7.2
7.6
7.3
7.5
7.6
7.4
7.6
6.8
7.4
7.2
7.7
7.4
7.4
7.8
8.0
7.2
7.4
8.0

1.00
0.59
1.68
2.11
1.76
1.03
0.93
0.96
0.67
1.65
1.29
1.48
0.58
0.76
1.21
0.98
0.56
1.29
1.04
0.64

1
4
8
1
7
1
5
1
1
3
5
3
1
11
4
4
9
7
7
8

29.6
29.5
28.6
29.9
28.8
28.2
29.9
29.1
29.6
27.7
28.5
28.1
28.6
30.1
27.2
27.0
26.6
29.1
28.3
27.2

8
4
3
2
3
6
2
2
2
7
4
3
4
4
5
11
5
9
4
11

1
<1
<1
<1
<1
<1
<1
<1
1
<1
<1
1
2
2
3
3
2
2
2
<1

20.53
5.81
30.65
71.33
49.46
15.16
25.67
16.08
21.63
37.35
32.99
29.74
9.62
10.01
30.08
45.31
23.90
86.90
32.49
47.62

2.35
11.61
2.57
31.85
12.32
29.10
19.89
17.32
56.88
10.76
17.98
12.18
10.50
13.20
4.21
16.79
36.99
56.88
5.89
7.22

<0.01
0.03
<0.01
0.03
<0.01
0.15
<0.01
0.03
<0.01
<0.01
0.03
0.03
0.03
<0.01
0.18
<0.01
0.03
<0.01
<0.01
0.03

342
307
381
443
357
392
318
350
284
419
369
462
276
342
326
303
252
419
353
206

6.5‐8.5

‐

2

‐

10

0.2

250

50

2

250

02) South Asia Pvt Ltd Pugoda, Gampaha
Sludge pits were damaged due to heavy rains followed by floods &affected surface water in Kelani river (2016)
Venegross Pvt Ltd
Well water contamination in Rathupaswala (Gampaha area) due toindustrial effluent discharge ( rubber glove manufacturing industry) on
land (2014)1603) Chemical accidents in industries & chemical storages
Leakage in under ground diesel tank and pollution of ground water andNilwala river in Southern Province. (2016)
Merbok Lanka Pvt Ltd( MDF board manufacturing) Horana EPZ (2022)
Water Care Pvt Ltd(chemical storage) Homagama (2023)
Sanitizer producing industry in Kandana (2023)

3. Legal background & enforcement
Institutions & Legal Framework related to Soil & Ground water
Management
DEPARTMENT OF AGRICULTURE
Recommendation for the fertilizer applications, using of pesticides,
weedicides
Execute the Soil Conservation Act No 25 of 1951 & its amendments.
WATER RESOURCE BOARD
Act No 29 of 1964, control, conservation & utilization of water
resources
CENTRAL ENVIRONMENTAL AUTHORITY
Protect, Mange & Enhance the quality of environment under National
Environmental Act No 47 of 1980
WATER SUPPLY AND DRAINAGE BOARD
Drinking water supply & Drainage management.

FERTILIZER SECRETARIET IN SRI LANKA
Promotion of Production and use of organic fertilizer

National Environmental Act No. 47 of 1980
Management Policy on Soil Conservation
Article 22
The Authority in consultation with the Council shall, with theassistance of the Ministry charged with the subject of Soil
Conservation, recommend soil conservation programmes including
therein the identification and protection of critical watershedareas, encouragement of scientific farming technique, physical andbiological means of soil conservation, and short term, and longterm research and technology for effective soil conservation.
Management policy on soil conservation.

•
•
•
•

•

•

Act Amendments, No 56 of 1988 and No 53 0f 2000
Part IV A – Environment Protection
Part IV B – Environment Quality
Restriction regulation and control of pollution;
No person shall deposit or emit waste into the inland waters of Sri Lanka,
except in accordance with such standards or criteria prescribed under theAct.
The wastewater discharge standards are gazetted in 1990 and revised in2008 & 2022.
Protection of soil Quality
23M. ‐ No person shall discharge or deposit waste into the soil, except
in accordance with such standards or criteria•

23N ‐ Restriction, regulation and control of pollution of the soil.

•

Pollution of soil is an offence1.2 Legal Status of Ground Water Protection in Sri Lanka•

Multiple mandates governing the use and management of ground water
are dispersed among various agricultural, land and water managing
institutions.

•

50 legislative enactments and 42 institutions deal with water related
matters.

•

No single or formally accepted policy or law.

•

Draft policy in year 2000 have opposed by the public due to
implementing economic principles.

•

Extraction is freely open and only regulate industrial and commercial
withdrawals.

•

Fee is charged only if the water supplied in piped schemes•

No any regulation/guideline for ground water recharging

21

4. Reviewing & setting tolerance limits
Background Information
•
•
•
•

•
•
•
•

Ground water usage of Sri Lanka is widely spreading (especially in Dry zone)
Quality is directly connects with the quality of soil.
Hardness of the ground water is a major issue in SL. Mostly in the dry zone,
the hardness ranges between 250‐500 ppm.
Higher fluoride concentration of the water in the dry zone (Dissanayake andWeerasooriya, 1985).
A study carried out in Attanagalu basin in Gampaha district revealed that thewell water is acidic ( low PH) in many localities due to soil characteristics

Ground water table is depleting year to year due to various reasons andneed to recharge and improve
As the facilities to discharge wastewater is limited the industries dispose
their treated effluent on land for irrigation purposes.
This is a way to replenish the ground water table as the ground water isscares in some regions.
Continuous discharge of effluent on land have caused various problems
in ground water which result a bad quality in ground water regime &well water.

Actions taken in connection with standard review process•

WEPA Action programme for the year 2017/2018 was focused on ground waterpollution by industrial effluent discharges in Gampaha area.

•

Objectives‐•

To evaluate the wastewater pollution control strategies and sludge disposal methods inselected high polluting industries.
Investigate water quality in selected areas to identify if any impact to ground water quality
due to Industrial discharges.
Develop new Policies, Guidelines or improve existing guidelines related to Industrial siting
and waste disposal to prevent ground water pollution.
Develop ground water maps.

•
•
•

•
•
•
•
•
•
•
•

Results
quality of water in nearest wells of industries exceed the drinking water quality
limits.
In some locations background values exceeding tolerance limits ( SLS standards)
demands careful monitoring of discharge to avoid worsening the present status.
Need improvements to current treatment processes in industries.
Outcomes
Restrict on land disposal of treated effluent for chemical related industry types.
Incorporate the findings in introducing the regulation for siting.
Improve existing treatment processes & disposal of waste.

Sample Data & Water Quality Parameter Trends
WEPA Data Table Ex: Oxford Dyeing Pvt Ltd
Table No: 05 pH levels of the wells surrounding Oxford Dyeing Pvt Ltd with Seasonalvariation

Well No.

Sampling Location
pH Tested Method :Electrometric
APHA, 4500 -H + B Tolerance limits:6.0 – 8.5

W26
W-27
W-28
W-29
W-30
W-31
W-32

Distance fromthe industry

07/11/2017
5.6

19/01/2018
5.7

06/04/2018
5.7

18/9/2018

Meters
0

4.6

4.1

4.1

5.4

141

H M Gamini Wijesiri
91/5 A 1, Pahala Karagahaamuna, Kadawatha

5.8

5.9

6

3.9

175

L Dehigama
105/2L Ragama road, Kadawatha

4.2

4.3

4.5

4.5

194

Roshan Madusanka (Public well)
105/20/2, Ragama road, Kadawatha

5.6

5.9

6.6

6.3

56

Mangala Chamali
84 G, Ragama road, Kadawatha

4.1

4.1

4.6

4

233

Chandrawimala Pinto
81/3 Pahala Karagahaamuna Kadawatha

4.8

4.3

4.3

4.2

525

Oxford Dying, Ragama Road, Kadawatha
Padma Malani
91/3 A , Pahala Karagahaamuna, Kadawatha

Industry Category

Location of Industries & Wells with Elevation

Selected wells around South Asia Textiles Lanka (Pvt) Ltd, Pugoda, Gampaha District

SLSI Standards for Drinking Water PH 6.5 – 8.5
The results indicates the background pH values of the area in the acidic range regardless of the discharge.

Venigross Industry
A study was conducted regarding the effect of on land disposal of chemical based
wastewater from a rubber glove manufacturing industry in Gampaha District,
Well water samples were analyzed in 2013, 2014 & 2015 to check the trends of pollutants
in well water samples, during operational stage in 2013 & after relocation of the industry
in 2014 & 2015.
The results obtained shows a significant decrease in pollutants levels which present in
wastewater.
Measured Parameters
Electrical conductivity(EC)pH
Temperature
Chloride as ClPhosphate as PO43Nitrate as NO3Sulphate as SO42Zinc as Zn2+
Copper as Cu2+
In the year 2015, most of the measured parameters were within the guideline values for drinking water issued
by Sri Lanka Standard Institute (SLSI).
pH value of well water within the latex factory was between pH 5.2 to 6.8 and well water around the latex
factory was between pH 3.6 to 5.9.

Nitrate as NO 3‐
250
200

NitrateConcentration
(ppm)

150
100
2013
50

2014

0
0

2

4

6

Well No2015

8

Standard

pH
8
7
6
5
pH

4

2013

3

2014

2

2015

1

Standard

0
0

2

4

6

8Well No

Sulphate as SO 4 2‐
400
350
300
Sulphate
Concentration
(ppm)

250
200
2013

150

2014

100

2015

50

Standard
0
0

1

2

3

4

5

6

7

8

Well No

Reviewing & setting tolerance limits contd..
Effluent Discharge Standard No. 1534/18 dated 2008.02.01
Paramete Inlandrsurfacewaters

TDS(mg/l )

Irrigation

RubberMarinecoastal
areas

Type
I

Type II

TextileTanningInlandPublic Sewers

Marinecoastal

‐

2100

150

‐

‐

‐

‐

‐

500

6.0 – 8.5

5.5 ‐9.0

5.5 ‐9.0

6.0 –
8.5

6.0 –
8.5

6.0 –
8.5

5.5 ‐9.0

5.5 ‐9.0

5.5 ‐10.0

BOD(mg/l)

30

250

100

60

50

60

60

100

350

COD
(mg/l)

250

400

250

400

400

250

250

300

850

Oil
&
grease

10

10

20

‐

‐

‐

10‐

20

30

Chlorides

‐

600

300

60

70

1000

‐

900

Sulphates

‐

1000

50

300

40

60

-

-

1000

EC

‐

225

‐

‐

‐

-

-

-

-

PH

Treated wastewater disposal for irrigation••

In 1990 ; only the standard limits are given to dispose on land
In 2008 ; treated wastewater disposed as per the Hydraulic Loading
Soil Texture
Class
Applicablefor Different
SoilsRecommended dosage of settled
Industrial Effluents(m3 /hectare, day)

1.

Sandy

225 ‐ 280

2

Sandy loam

170 ‐ 2253

Loam

110 ‐ 170

4Clay loam

55 ‐ 1105Clay

35 ‐ 55

2008 standard was revised with expert consultation & groupmeetings.
•With universities, relevant agencies involved in soil /agriculture
such as research institutes for tea, rubber, coconut & paddy• Reference of international standards and best practices

Effluent Discharge Standard No. 2264/17 dated 2022.01.27
Parameter

Marine waters

CoastalwatersInlandsurface

Agriculture

Leachates Public Sewers

Near
shore

short

Long

TDS

2100

‐

‐

1000

1000

2000

‐

3000

PH

6.5 – 8.5

5.5 ‐9.0

5.5 ‐9.0

6.5 – 8.5

6.5 – 8.5

6.5 – 8.5

6.5 – 8.5

5.5 ‐9.0

BOD (mg/l)

15

75

400

30

30

250

80

400

COD (mg/l)

50

400

800

250

250

400

1000

800

Oil
grease

5

12

15

10

10

10

‐

20

Chlorides

‐

‐

‐

Not
change
20%

400

300

‐

1200

Sulphates

‐

‐

‐

250

250

350

-

350

EC

‐

‐

‐

‐

-

2500

-

-

Nitrate

‐

‐

‐

‐

10

10

-

-

Discharge
rate

‐

‐

‐

‐

-

To be
decided by
infiltration
rate

-

-

&

Standards for discharge of wastewater on land for agriculture
purposes•

Ground water table– The effluent discharge on land only be allowed considering the height of theground water table which shall be at least 0.5m below the ground surface.

•Slop of the land
– Natural slope of the ground shall not be steeper than 30% (or 16.7 degrees).

•

Discharge rate and volume– Discharge rate is decided based on design infiltration rate done by a competentauthority for the soil investigation;•

In order to consider the possibility of land application for agricultural
purpose, a report on infiltration rate should be obtained including
following details;‐ Method of delivery of effluents to the land

‐ Method of irrigation over the land
‐ Number of hours of application,‐ Effluent storage facilities & types of crops etc•

Standard test method for infiltration‐ Using double‐ring infiltro meters as

stipulated in ASTM D3385‐09 or by a standard test method followed at present )•In case if the soil layers are different, the number of in‐situ tests to be carriedout for the land to which the effluents discharge is planned shall be decided
as follows:‐– (i) For a land having an extent up to 0.1 hectare (1000 m2) ‐ 1 test
– (ii) For a land having an extent greater than 0.1 hectare (1000 m2) and up to 1.0
hectare (10,000m2) ‐ 2 tests– (iii) For a land having an extent greater than 1.0 hectare (10,000 m2) and up to 5.0 hectare(50,000m2) ‐ 3 tests– (iv) For a land having an extent greater than 5.0 hectare (50,000 m2) ‐ 5 tests•

The project developer could adhere to the given infiltration rate in deciding
the land requirement for disposal of effluent for the purpose of agriculture.

5. Issues and limitations in implementation• Facilities for Soil testing labs private/government.
• Areas with high water table• Areas closer to water sources should comply “standards
for Inland surface waters”• Difficulties in applying for small land plots ‐ No
infiltration rate testing• Prioritize the food sector and Chemical based wastewater
is not encouraged.
• If treatment is not adequate, continuous discharge may
cause clogging in soil strata.
• Financial constrains in SMEs for soil testing• Accumulation of heavy metals and chemicals• Soil stability

6. Way Forward• Proper implementation of regulations by promoting
treated waste water for irrigation ie. solution for water
scarcity.
• Promoting & increasing soil testing facilities.
• Initial soil testing before establishment of industries so
as to monitor their disposal rate and accumulation ofpollutants in soil (site approval stage)• Prepare & gazette Soil pollution control regulations inline with the standards for treated wastewater disposalon land.
• Improve coordination among relevant stakeholder
institutions regarding soil / ground water• Improve collaboration with partner countries for
guidance, system improvements and further research.

THANK YOU

5. Sample Data & Water Quality Parameter Trends
WEPA Data Table Ex: Oxford Dyeing Pvt Ltd
Table No: 05 pH levels of the wells surrounding Oxford Dyeing Pvt Ltd with Seasonal variation
Well No.

Sampling Location
pH Tested Method :Electrometric
APHA, 4500 -H + B Tolerance limits:6.0 – 8.5

W26
W-27
W-28
W-29
W-30
W-31
W-32

Distance fromthe industry

07/11/2017
5.6

19/01/2018
5.7

06/04/2018
5.7

18/9/2018

Meters
0

4.6

4.1

4.1

5.4

141

H M Gamini Wijesiri
91/5 A 1, Pahala Karagahaamuna, Kadawatha

5.8

5.9

6

3.9

175

L Dehigama
105/2L Ragama road, Kadawatha

4.2

4.3

4.5

4.5

194

Roshan Madusanka (Public well)
105/20/2, Ragama road, Kadawatha

5.6

5.9

6.6

6.3

56

Mangala Chamali
84 G, Ragama road, Kadawatha

4.1

4.1

4.6

4

233

Chandrawimala Pinto
81/3 Pahala Karagahaamuna Kadawatha

4.8

4.3

4.3

4.2

525

Oxford Dying, Ragama Road, Kadawatha
Padma Malani
91/3 A , Pahala Karagahaamuna, Kadawatha