2. PROJECT DESCRIPTION
2.1 PROJECT BACKGROUND
2.2 NEED OF THE PROJECT
2.3 PROJECT DESCRIPTION
2.4 PROJECT LOCATION
2.5 CONSIDERATION OF SEWAGE
TREATMENT OPTIONS
2.6 COMPARISON OF SEWAGE
TREATMENT OPTIONS
2.7 PRELIMINARY LAYOUT
AND PROCESS FLOW DIAGRAM
2.8 PROJECT PROGRAMME
2.9 INTERACTIONS WITH OTHER
PROJECTS
2.10 CONSTRUCTION METHODS
FOR THE UPGRADING WORKS
2.
ProJect
Description
2.1
Project Background
2.1.1.1
The existing Pillar
Point Sewage Treatment Works (PPSTW) is a preliminary treatment works of 5.79 m3/s
capacity. The operation of the existing
PPSTW is to remove screenings followed by grit removal prior to discharging its
effluent into the sea via twin submarine outfalls. Under the Review of
the Tuen Mun and Tsing Yi Sewerage Master Plan (RTMTYSMP) commissioned in February
1999, recommendation was made to upgrade the existing PPSTW to chemically enhanced primary
treatment with disinfection. Figures
2.1 and 2.2 show the location and layout of
existing PPSTW.
2.1.1.2
The effluent discharged from the Project, with respect to the designed capacity of
the upgraded PPSTW at ultimate development scenario, must be able to meet the
Water Quality Objectives of the North Western Water Control Zone as set out
under the Water Pollution Control Ordinance (Cap. 348) and to improve the
aquatic environment therein as far as practically possible.
The
impacts on environment must be kept within the limits set out under the EIA
study of this Assignment throughout the construction and operation of the
Project.
2.1.1.3
The EIA Study is to provide
information on the nature and extent of environmental impacts arising from the
construction and operation of the Project following the preliminary
design and related activities that take place
concurrently.
2.2
Need of the Project
2.2.1.1
The aim of the upgrading works
is to expand the sewage treatment capacity and to upgrade the treatment level
of the PPSTW in order to cater for the projected ultimate population and
planned developments in the Tuen Mun area. The Project will improve the
effluent quality and reduce the pollution loadings to the receiving waters,
namely the North Western Water Control Zone.
2.3
Project Description
2.3.1
Project Objective
2.3.1.1
A
Preliminary Project Feasibility Study (PPFS) for the Project was completed in June 2001 after the RTMTYSMP confirmed the viability of the
upgrading works to the PPSTW, which comprised the
following:
Ÿ
expanding the treatment capacity of the existing
PPSTW to cope with the increased peak wet weather sewage flow under the
ultimate development scenario (UDS);
Ÿ
upgrading the sewage treatment level of the
existing PPSTW to incorporate chemically enhanced primary treatment (subject to
EIA Study under the Assignment) with disinfection;
Ÿ
providing proper septic waste reception
facilities at the PPSTW; and
Ÿ
providing and upgrading ancillary facilities
within the PPSTW for the operation and maintenance of the upgraded PPSTW.
2.3.1.2
The construction of the upgrading works and the operation and maintenance of the
upgraded PPSTW will be implemented under a
design-build-operate (DBO) contract arrangement. A preliminary
design taking into account all the Project requirements
is carried out. In the preparation of the preliminary design, the sewage flows and loads are to be estimated in order to
determine the treatment capacity and effluent standards of the upgraded
PPSTW. Moreover, an
appropriate treatment process is to be selected for the
upgraded PPSTW.
2.3.2
Design Flow and Loads
2.3.2.1
In estimating the sewage flow
for the preparation of the preliminary design, the 2003-based Territorial Population and Employment Data Matrices
(TPEDM) provided by the Planning Department were utilized for the population
projection for the PPSTW catchment. The design flows were then projected on the basis of the unit flow
factors recommended in the Guidelines for Estimating
Sewage Flows for Sewage Infrastructure Planning (Version 1.0), EPD, March
2005. The projected Average Dry Weather
Flow (ADWF) and Peak Wet Weather Flow (PWWF) for the PPSTW catchment are summarized in Table 2.1.
Table 2.1 Projected ADWF and PWWF for
PPSTW Upgrading
|
Year
|
Flows from
Septic Waste
(m3/d)
|
ADWF (1)
(m3/d)
|
PWWF (2)
(m3/d)
|
|
2012
|
1200
|
199,000
|
457,000
|
|
2016
|
1200
|
211,000
|
483,000
|
|
UDS
|
1200
|
230,000
|
525,000
|
Note:
(1) ADWF
includes the average flows from DWFIs, average leachate flow and maximum design
flow of septic waste.
(2) PWWF
includes the maximum flows from DWFIs, design maximum leachate flow and maximum
design flow of septic waste.
(3) Total
average and maximum flow from DWFIs are 0.22 m3/s and 0.44 m3/s respectively.
(4) The
average and design maximum leachate flows are 900 m3/day and 2,700 m3/day respectively.
(5) ADWF and PWWF are
roundup figures.
2.3.2.2
In estimating the sewage loads
for the preparation of the preliminary design, the global unit load factors recommended in DSD Sewerage Manual
Part 1 (SM1) were adopted in the loads projections. The estimated pollution
loads have been compared with the results from laboratory tests conducted in
Years 2000 and 2006. With application of correction factors to the estimated
pollution loads derived using the SM1, the corrected average pollution loads
from 2012 to UDS is shown in Table 2.2.
Table 2.2 Corrected Average Pollution Loads for PPSTW
Upgrading
|
Year
|
Pollutant Concentration
|
|
SS
|
BOD
|
COD
|
TKN
|
NH3-N
|
E.Coli.
|
|
mg/L
|
mg/L
|
mg/L
|
Mg/L
|
mg/L
|
counts/100ml
|
|
2012
|
271
|
286
|
951
|
47
|
22
|
2.81 x 107
|
|
2016
|
268
|
281
|
935
|
47
|
22
|
2.81 x 107
|
|
UDS
|
268
|
282
|
937
|
47
|
22
|
2.81 x 107
|
2.3.2.3
The following design flows and
pollutant concentrations based on ultimate scenario are recommended for the PPSTW upgrade.
·
ADWF = 230,000 m3/day
·
PWWF = 525,000 m3/day (6.08 m3/s)
·
Influent Loads Note:
-
TSS = 270 mg/l
-
BOD = 280 mg/l
-
COD = 940 mg/l
-
TKN = 47 mg/l
-
NH3-N = 22 mg/l
-
E. coli = 3 x 107 counts/100 ml
Note: The influent loads being stated are average
values for design purpose.
2.4
Project Location
2.4.1.1
The PPSTW is located at north
of the Tuen Mun River Trade Terminal bounded by Lung Mun Road at the north. The
location of the Project site with a total area of about 5.0
hectares is shown in Figure 2.1, which covers the
existing PPSTW (about 1.7 hectares) and an open area (about 3.3 hectares)
adjacent to it. The open area has been
designated for the future upgrading of the treatment works. The design of the
PPSTW upgrade shall therefore be confined within the extent of the existing PPSTW and the open area, and impact during construction and operation on the existing road
etc. must be fully assessed.
2.5
Consideration of Sewage Treatment Options
2.5.1.1
Based on the RTMTYSMP and the
subsequent PPFS, the minimum removal efficiency of TSS, BOD5 and E.coli for PPSTW upgrading should be 70%, 55% and 99.9%
respectively, which is achievable by chemically enhanced primary treatment
process (CEPT) with disinfection.
2.5.1.2
Water quality assessment (see Section 4) indicates that there will be
improvement for BOD5, TSS and E.Coli in sensitive water
bodies due to the proposed upgrading works because of the reduced overall
loadings of BOD5, TSS and E.Coli from the effluent discharge
after the upgrading of current preliminary treatment process, based on the
results of mathematical water quality modelling. The assessment also indicates that there
will be increase in the TIN levels in the receiving waters as compared to the
existing baseline level which already breached the WQO. However, the assessment indicates such increase
in the TIN level would unlikely increase the chance of algal bloom in the
receiving waters. Consideration of other
feasible sewage treatment options for the Project, i.e. secondary treatment
with nitrogen removal plus disinfection
has also been made and the impact on the water quality has been assessed. The assessment indicates that the reduction
of TIN levels is insignificant. Based
on water quality impact assessment results, CEPT with disinfection is found to be the most effective treatment option for
PPSTW in minimizing the water quality
impacts. The effluent quality standards
are shown in Table 2.3.
Table 2.3
Recommended Effluent Standards for Upgraded PPSTW
|
Parameters
|
Concentrations
|
Remarks
|
Concentrations
|
Remarks
|
Sampling
Method
|
Sampling Frequency
|
|
TSS
|
80 mg/L
|
average
|
120 mg/L
|
95%ile
|
24-hour Composite
|
2 times a week
|
|
BOD5
|
120 mg/L
|
average
|
180 mg/L
|
95%ile
|
24-hour Composite
|
2 times a week
|
|
E.coli
|
20,000 counts/100ml
|
geometric mean
|
300,000 counts/100ml
|
95%ile
|
Grab Sample
|
3 times a week
|
Remarks:
(a) The
recommended sampling method and sampling frequency will be incorporated into
the discharge license to be issued by EPD.
2.5.1.3
The water
quality impact assessment (provided in Section 4) showed that, with the
adoption of effluent standards (which are equivalent to 99.9% E.coli removal) recommended in Table 2.3, the discharge of PPSTW
effluent after disinfection would not cause any adverse water quality impact on
the nearby bathing beaches in the Tuen Mun District.
2.6
Comparison
of Sewage Treatment Options
2.6.1
General
2.6.1.1
The purpose of this Section is to present the comparison of engineering and environmental
benefits and dis-benefits of possible sewage treatment options. The selection of the
preferred option will take into consideration of avoiding the adverse
environmental impacts to maximum practicable extent. The objective of PPSTW
upgrading works is to improve the effluent quality, and to meet the demand of
future population and pollutant loads at UDS. With reference
to the RTMTYSMP and the subsequent PPFS, the
minimum treatment level for PPSTW upgrading is to be able to achieve 70%, 55%
and 99.9% removal of TSS, BOD5 and E.coli. Various treatment processes
have been considered and it is found that chemically enhanced primary treatment
(CEPT) method is possible for the PPSTW upgrading works. CEPT is a sewage treatment process using
chemicals to coagulate and flocculate with raw sewage in order to enhance the
performance of primary sedimentation with higher removal of TSS and BOD. The treatment method is capable to fulfil the Project requirements without causing adverse water quality and
ecological impacts.
2.6.1.2
Viewing
that there is a general understanding that secondary treatment processes, which
are capable to remove biodegradable organic matter (in solution or suspension)
and suspended solids, have an advantage of producing better quality of treated
effluent over primary treatment processes. In this
regard, secondary treatment processes are also
considered for the
PPSTW upgrading works.
2.6.1.3
Five options adopting CEPT process and four other options adopting compact secondary treatment
processes, which are widely used in sewage treatment works, are identified and evaluated for the
PPSTW upgrading works. For the five options adopting CEPT process, their sewage treatment
mechanisms are identical. The effluent
standards achieved by the five CEPT process options are similar. Similarly, the sewage treatment mechanisms of
all the options adopting compact secondary treatment process are identical and
the achievable effluent standards amongst the selected options have no
significant difference.
2.6.1.4
However, all the options with
adopting CEPT process or compact secondary treatment process are different in
geometry and the selection
of the sewage treatment options is therefore based on
their advantages and disadvantages in different engineering aspects, including “Sludge Production”, “Ease of Operation”, “Hydraulic Head Requirements” and “Land Requirement”. However, taking into account the
environmental benefit, the option with
low “sludge production” is a preferable option.
Details of the selection exercise and details of the preferable option for the PPSTW upgrading works are
presented in Section 2.6.2.
2.6.1.5
CEPT and secondary
treatment process have been considered for PPSTW upgrading works. Different options are available for each
treatment process. Provided that same
treatment process is adopted, the effluent standards achieved by these options
are similar. Therefore these options
have no difference in terms of water quality or marine ecology impact. However, secondary treatment process could
produce better water quality than CEPT process.
Assessment of the water and
marine ecology impact arising from using the two treatment processes are
presented in Section 4 and Section 6 of
this EIA report respectively.
List of
Possible Options
2.6.2.1
The
following chemically enhanced primary treatment (CEPT) options, including
available proprietary high rate clarification processes, have been identified for
evaluation:
· CEPT with Primary Clarifiers (Single-deck)
· CEPT with Primary Clarifiers (Multi-level)
·
CEPT with Lamella Clarifiers
· Actiflo Process (Proprietary High Rate Clarification
Process)
· DensaDeg (Proprietary High Rate Clarification Process)
General descriptions
of the proposed processes are presented in Appendix
2-1.
2.6.2.2
Since the site
area required for secondary treatment process is
generally large and the land available for the PPSTW upgrading works is
limited, only compact secondary treatment processes are considered feasibility for the Project. In
addition, the conventional activated sludge process is a common secondary
process being used in Hong Kong and a feasible
option for the Project. A list of the identified secondary
processes for evaluation is given below:
· Biological Aerated Filter (BAF)
· Sequencing Batch Reactors (SBR)
·
Membrane
Biological Reactor (MBR)
· Activated
Sludge Process
General descriptions of the proposed
processes are presented in Appendix 2-1.
Option Assessment
2.6.2.3
All the CEPT
and secondary treatment options mentioned above are capable to fulfil the Project requirements and have
similar water quality and ecological impacts.
Selection of the sewage treatment processes are
therefore mainly considering their advantages
and disadvantages in different engineering aspects, including “Sludge Production”, “Ease of Operation”, “Hydraulic Head
Requirements” and “Land Requirement”.
Results of option assessment in respect of the four
engineering aspects are detailed in Table 2.4.
It is
revealed that, with reference to Table 2.4, adopting secondary treatment processes will warrant
environmental disbenefits in collecting, handling and disposal of increased
quantities of sludge produced due to higher removal efficiencies and also
warrant environmental disbenefits in the associated odour control due to
increased treatment units and surface areas. On the other hand, all five CEPT
options will produce less sludge and less potential for odour emission, when
compared with secondary treatment processes. Moreover, the CEPT processes
render relatively less land requirement.
Table 2.4 Shortlisting
of Promising Processes
|
|
Sludge
Production
|
Ease of
Operation
|
Hydraulic
Head Requirements
|
Ability to
Meet Effluent Standards
|
Land
Requirement(a)
|
|
Chemically Enhanced Primary Treatment Process
|
|
CEPT with Conventional Clarification (Single-deck)
|
Low
|
Easy
|
Low
|
Yes
|
~1 Hectare
|
|
CEPT with Conventional Clarification (Multilevel)
|
Low
|
Easy
|
Low
|
Yes
|
~ 0.5 Hectare
|
|
CEPT with Lamella Clarification
|
Low
|
Moderate
|
Low
|
Yes
|
~ 0.5 Hectare
|
|
Actiflo Process
|
Medium
|
Moderate
|
Medium
|
Yes
|
<0.5 Hectare
|
|
DensaDeg Process
|
Medium
|
Moderate
|
Medium
|
Yes
|
<0.5 Hectare
|
|
Secondary Treatment Process
|
|
Activated Sludge Process
|
High
|
Moderate
|
High
|
Yes
|
> 3 Hectares
|
|
SBR Process
|
High
|
Moderate
|
High
|
Yes
|
~ 3 Hectares
|
|
BAF Process
|
High
|
Moderate
|
V.High
|
Yes
|
> 2 Hectares
|
|
MBR Process
|
Moderately High
|
Moderate
|
V.High
|
Yes
|
> 2 Hectares
|
Remarks (a):
- For the primary sedimentation processes, the land
requirement includes the process tanks associated to CEPT/sedimentation process
only.
- For the secondary treatment processes, the land
requirement is developed from single-storey design and includes the liquid
stream of sewage treatment only.
2.6.2.4
Although secondary treatment
processes generally have an advantage of producing better quality of treated
effluent over primary treatment processes, in assessing the associated water
quality impacts on the aquatic environment (findings are presented in Section 4
of this EIA Report), it is indicated in the water quality impact assessment that there would be no substantial improvement in the extent of water
quality impacts resulting from the adoption of an even higher treatment level
(secondary treatment plus nitrogen removal and disinfection). As such, it is concluded that CEPT plus
disinfection would be the most effective treatment option for the PPSTW in
minimizing the water quality impacts (refer to Section 4.7.2.12 to Section
4.7.2.23). Moreover, the secondary treatment process renders relatively
large footprint of site area.
2.6.2.5
Based
on the assessment in 2.6.2.3 and 2.6.2.4, the five CEPT processes are
retained for further evaluation.
Preferred Sewage
Treatment Options
2.6.2.6
Of the selected five CEPT
processes, they have their own advantages and disadvantages. Since all the five processes adopt similar
technology of using chemicals to coagulate and flocculate with raw sewage in
order to enhance the performance of primary sedimentation with higher removal
of TSS and BOD, their environmental impacts to water quality, marine ecology
and air quality are similar. With
reference to the assessment results presented in Section 4 (Water Quality Impact Assessment) and Section 6 (Marine Ecological Impact
Assessment), it is noted that all the selected five CEPT processes create no
adverse impacts to the water quality and the marine ecology. Moreover, referring to the assessment results
as presented in Section 3 (Air
Quality Impact Assessment), the impact to the air quality is able to be
mitigated by providing common deodorizing units with practically achievable
odour removal efficiency of 90%, as such, all
of the five CEPT processes are considered to be appropriate for the
upgrading of PPSTW.
2.6.2.7
Based on the preliminary
design, the single clarifier option is
adopted in view of its relative large footprint
with no proprietary processes like Actiflo and
DensaDeg.
2.6.3.1
Disinfection is the destruction of pathogenic
microorganisms. Chlorination and
Ultraviolet irradiation (UV) are the most widely used disinfection methods in Hong Kong and they are further considered and evaluated.
2.6.3.2
Chlorine, as a form of hypochlorite, is a common disinfectant
used for chlorination. It is an effective and readily available
disinfectant. However, chlorination generates by-products if not properly
controlled and they would cause some detrimental impacts to human and marine
fauna at high dosage. These by-products
include trihalomethanes (THMs), chloramines and haloacetic acids. The concentration of these by-products in the
chlorinated effluent can be reduced by lowering the total residual chlorine
(TRC) through dechlorination, thereby reducing the toxicity of effluent.
2.6.3.3
UV irradiation is a physical disinfection process and no
harmful effluent by-products would be produced.
UV irradiation, at a suitable wavelength, modifies the DNA in the cells
of pathogens so that they can no longer reproduce, and thus they will present
no threat to human health. Moreover, effluent disinfection by UV
irradiation also would have the beneficial effect of controlling pathogen
levels (measured as E.coli) thereby
protecting marine water quality at water sensitive receivers. As presented in Section 6, the reduction of E. coli, BOD5, SS and sedimentation
rate in the receiving water and a slight increase in DO
level localized at the PPSTW outfall after
the upgrading works would have a positive impact on marine ecology as
well as the health of the Chinese White Dolphin and its prey. Moreover, with the same treatment capacity,
UV irradiation requires less space than chlorination facilities in general.
2.6.3.4
Both chlorination and UV irradiation are proven disinfection
processes. At this stage there is no enough information to conclude which
one is a preferred option in terms of effectiveness as well as environmental
impacts. In view of the limitation of
the land area for the upgrading for this project, UV irradiation technology
will be adopted as the disinfection method in the
preliminary design of the upgraded PPSTW. The water quality impact assessment results as presented in Section 4
showed that the discharge of effluent from the upgraded PPSTW after CEPT and UV
disinfection would not cause adverse water quality impacts.
2.6.3.5
There is some local and
international experience with disinfection of CEPT effluents by UV irradiation. For example, locally, the Sui Ho Wan CEPT STW
(Phase 1) (design ADWF 96,000m3/d) uses UV disinfection. Internationally, the Canadian Halifax
(133,920m3/d) and the US
Hawaiian Sand Island (320,000m3/d)
CEPT plants use UV irradiation disinfection.
Overall, for the size of disinfection plant anticipated at PPSTW, it is
considered that disinfection of CEPT effluent by UV irradiation is proven.
General description of UV irradiation disinfection is presented in Appendix
2-2.
2.6.4
Septic Waste Reception
2.6.4.1
The septic waste is now being
discharged into the inlet chamber of PPSTW.
Generally, the quality of septic waste fluctuates according to the location.
It would be impractical to predict the quality variation of septic waste. The
fluctuation of quality and quantity of septic waste may have significant effect
on the treatment processes, especially when the quantity of septic waste
increases up to 1200m3/day in the future.
2.6.4.2
In the upgraded PPSTW, the
septic waste is proposed to be handled with the sludge stream instead of
discharged into the inlet chamber to facilitate odour control and wastewater
treatment process.
2.6.4.3
A
septic waste reception area with deodorization
facilities will established within the PPSTW site. Enclosed compact septage receiving stations will be built within the septic waste reception
area for suspended solids and grits removal
and for septic waste
collection. The deodorization facilities will minimize the odour impact to the nearby air
sensitive receivers. The collected septic waste will
then be discharged to the future sludge holding tanks in PPSTW for temporary
storage.
2.6.5.1
Currently, only screenings and
grit are being generated in the
PPSTW from the existing preliminary treatment process. Upon commissioning of the
upgraded PPSTW, sludge production is contemplated. Dewatering process will be
required for primary sludge to satisfy the disposal requirement of 30% dry solid content of sludge to EPD’s strategic landfills.
2.6.5.2
The estimated volume of primary
sludge to be handled in the dewatering process is 2260 m3/day. In
addition, a maximum volume of 1200m3/day
of septic waste is designed to be conveyed to the
sludge holding tanks for dewatering.
2.7
Preliminary Layout and
Process Flow Diagram
2.7.1.1
A preliminary layout plan for
the upgraded PPSTW with the recommended treatment options are shown in Figure
2.3. The maximum height of the new structures is approximate 17.5m
above the existing ground level. In addition, the process flow diagram is shown
in Figure
2.4.
2.8
Project
Programme
2.8.1.1
It is intended to implement the
upgrading works of the PPSTW and to
thereafter operate and maintain the whole of the STW under DBO contract arrangement. The DBO
contract is currently scheduled to commence in mid 2009 for completion of the construction in 2012. The major
construction activities for the Project would comprise site formation,
excavation and backfilling, erection of formwork and reinforcement, concreting,
fabrication of steelwork, and testing and commissioning.
2.9
Interactions
with Other Projects
2.9.1.1
No
other major project was identified to be carried out concurrently in the
vicinity of the Project site and within the 500m assessment
area for the air quality impact assessment and landscape impact
assessment. No cumulative construction
dust impacts are likely to arise from the Project. It is noted that there are planned
developments in the Tuen Mun Area 38, which include Permanent Aviation Fuel
Facility and EcoPark. However, all of
the developments are located outside 500m from the PPSTW site boundary and they
would only be considered in the visual impact assessment of the Project.
Environmental effects of the existing developments located within 500m from the
PPSTW site boundary, which include River Trade Terminal (RTT), have been
considered in the assessment of the Project.
Cumulative impacts from effluent discharge from other sewage treatment
facilities in the assessment area including Stonecutters Island STW, San Wai
STW, Siu Ho Wan STW, Sham Tseng STW, Yuen Long STW and Shek Wu Hui STW have
been considered in the water quality impact assessment.
2.10
Construction Methods for the
Upgrading Works
The construction
works involved in this project include Civil & Structural works, E&M
works and Building Services works. For
Civil & Structural works, bore-piling will be adopted for foundation,
tradition excavation and cast-in-situ concreting will be adopted for pile caps,
basements and superstructures constructions.
For E&M works, general fixing and installation of treatment plants
and facilities such as UV lamps, pumps and conveyors are required. For Building Services works, small sized
utilities installations such as pipe-laying, ducting and cabling will be
conducted. As such, apart from Civil
& Structural works, all the works involved in the PPSTW Upgrading are considered
to create no adverse impact to the environment.
For foundation,
piling is required since the site is a reclamation area with deep level of rock
head. Bore-piling is preferred since it
is a non-displacement piling method, which produces less noise and ground vibration
then the other displacement piling methods. General description of bore-piling
process is presented in Appendix 2-3.
Due to the
hydraulic requirement, some facilities are required to be constructed below the
ground level and therefore, excavation for underground structures like
basements and pile caps is required. Air
quality and water quality impacts during the construction phases have been
assessed and presented in Section 3 and Section 4 respectively. It is concluded that with implementation of
mitigation measures specified in the Air Pollution Control (Construction Dust)
Regulation and stated in Section 3.7.1, dust nuisance is not expected. It is also concluded that only minor water
quality impact would be associated with the land-based constructions. Impacts may result from the surface runoff
and sewage from on-site construction workers, which however could be controlled
to comply with the WPCO standards by implementing the recommended mitigation
measures and unacceptable residual impact on water quality is not expected.