Or. Admin. R. 333-061-0050 - Construction Standards
(1)
General:
(a) These standards shall apply to
the construction of new public water systems and to major additions or
modifications to existing public water systems and are intended to assure that
the system facilities, when constructed, will be free of public health hazards
and will be capable of producing water which consistently complies with the
MCLs;
(b) Facilities at public
water systems must comply with the construction standards in place at the time
the facility was constructed or installed for use at a public water system. A
public water system shall not be required to undertake alterations to existing
facilities, unless the standard is listed as a significant deficiency as
prescribed in OAR 333-061-0076(4) or if MCLs are being exceeded.
(c) Non-public water systems that are
converted to public water systems shall be modified as necessary to conform to
the requirements of this rule.
(d)
Facilities at public water systems shall be designed and constructed in a
manner such that contamination will be effectively excluded, and the structures
and piping will be capable of safely withstanding external and internal forces
acting upon them;
(e) Only
materials designed for potable water service and meeting NSF Standard 61:
Drinking Water System Components - Health Effects or equivalent shall be used
in those elements of the water system which are in contact with potable
water;
(f) New tanks, pumps,
equipment, pipe valves and fittings shall be used in the construction of new
public water systems, major additions or modifications to existing water
systems. The Authority may permit the use of used items when it can be
demonstrated that they have been renovated and are suitable for use in public
water systems;
(g) Prior to
construction of new facilities, the water supplier shall submit plans to the
Authority for approval as specified in OAR 333-061-0060(1)(a).
(h) Construction may deviate from the
requirements of this section provided that documentation is submitted, to the
satisfaction of the Authority, that the deviation is equal to or superior to
the requirements of this section as specified in OAR 333-061-0055 (variances
from construction standards).
(i) A
public water system or other Responsible Management Authority using
groundwater, or groundwater under the direct influence of surface water,
derived from springs, confined or unconfined wells that wish to have a state
certified wellhead protection program shall comply with the requirements as
specified in OAR 333-061-0057, 0060, and 0065, as well as OAR 340-040-0140
through 0200. Additional technical information is available in the Oregon
Wellhead Protection Guidance Manual.
(j) As used in this rule, the following
definitions apply:
(A) "Confined well" means
a well that is constructed to draw water from a confined aquifer. More
specifically, it is a well which produces water from a formation that is
overlain by a low permeability material such as clay or unfractured
consolidated rock such that the water-level in the well rises above the top of
the aquifer. This well shall be constructed according to OAR chapter 690,
division 200 "Water Supply Well Construction Standards."
(B) "Impermeable material" means a material
that limits the passage of water.
(C) "Impounding reservoir" means an uncovered
body of water formed behind a dam across a river or stream, and in which water
is stored.
(D) "Pilot study" means
the construction and operation of a scaled down treatment system during a given
period of time to determine the feasibility of a full-scale treatment
facility.
(E) "Sensitivity" means
the intrinsic characteristics of a drinking water source such as depth to the
aquifer for groundwater or highly erodible soils in a watershed that increase
the potential for contamination to take place if a contaminant source is
present.
(F) "Unconfined well"
means a well that is constructed to draw water from an unconfined aquifer. More
specifically, it is a well which produces water from a formation that is not
overlain by a low permeability material such that the water-level in the well
does not rise above the top of the aquifer. This well shall be constructed
according to OAR chapter 690, division 200 "Water Supply Well Construction
Standards."
(k) All new
groundwater sources, whether additional or modified wells or springs, are
subject to consideration for potential direct influence of surface water as
prescribed in OAR 333-061-0032(7).
(2) Groundwater:
(a) Wells:
(A) For the purpose of this rule, wells are
defined as holes or other excavations that are drilled, dug or otherwise
constructed for the purpose of capturing groundwater or groundwater in
hydraulic connection where part of the water supplied by the collection system
is derived, either naturally or induced, from a surface water source as a
source of public drinking water.
(B) The area within 100 feet of the well
shall be owned by the water supplier, or a perpetual restrictive easement shall
be obtained by the water supplier for all land (with the exception of public
rights-of-way) within 100 feet of the well. The easement shall be recorded with
the county in which the well is located and with the recorded deed to the
property. A certified true copy shall be filed with the Authority.
(C) For wells located on land owned by a
public entity, (Federal, State, County, Municipality) where the entity is not
the water supplier, a permit may be issued by the public entity to the water
supplier in lieu of an easement. Said permit shall state that no existing or
potential public health hazard shall be permitted within a minimum of 100 feet
of a well site;
(D) Public or
private roadways may be allowed within 100 feet of a confined well, provided
the well is protected against contamination from surface runoff or hazardous
liquids which may be spilled on the roadway and is protected from unauthorized
access;
(E) The following sanitary
hazards are not allowed within 100 feet of a well which serves a public water
system unless waived by the Authority: any existing or proposed pit privy,
subsurface sewage disposal drain field; cesspool; solid waste disposal site;
pressure sewer line; buried fuel storage tank; animal yard, feedlot or animal
waste storage; untreated storm water or gray water disposal; chemical
(including solvents, pesticides and fertilizers) storage, usage or application;
fuel transfer or storage; mineral resource extraction, vehicle or machinery
maintenance or long term storage; junk/auto/scrap yard; cemetery; unapproved
well; well that has not been properly abandoned or of unknown or suspect
construction; source of pathogenic organisms or any other similar public health
hazards. No gravity sewer line or septic tank shall be permitted within 50 feet
of a well which serves a public water system. Clearances greater than indicated
above shall be provided when it is determined by the Authority that the aquifer
sensitivity and degree of hazard require a greater degree of protection.
Above-ground fuel storage tanks provided for emergency water pumping equipment
may be exempted from this requirement by the Authority provided that a
secondary containment system is in place that will accommodate 110 percent of
the fuel tank storage.
(F) Wells
shall not be located at sites which are prone to flooding. In cases where the
site is subject to flooding, the area around the well shall be mounded, and the
top of the well casing shall be extended at least two feet above the
anticipated 100-year (1 percent) flood level;
(G) Except as otherwise provided herein,
wells shall be constructed in accordance with the general standards for the
construction and maintenance of water wells in Oregon as prescribed in OAR
chapter 690, divisions 200 through 220;
(H) Wells as defined in paragraph (2)(a)(A)
of this rule that are less than 12 feet in depth must be constructed so as to
be cased and sealed from the surface to a minimum of three feet above the
bottom of the well. The casing may consist of concrete or metal culvert pipe or
other pre-approved materials. The seal shall be watertight, be a minimum of
four inches in thickness and may consist of cement, bentonite or concrete (see
concrete requirements prescribed in OAR 690-210-315). The construction and
placement of these wells must comply with all requirements of this
rule.
(I) Before a well is placed
into operation as the source of supply at a public water system, laboratory
reports as required by OAR 333-061-0036 shall be submitted by the water
supplier;
(J) Water obtained from
wells which exceed the MCLs shall be treated as outlined in section (4) of this
rule;
(K) The pump installation,
piping arrangements, other appurtenances, and well house details at wells which
serve as the source of supply for a public water system, shall meet the
following requirements:
(i) The line shaft
bearings of turbine pumps shall be water-lubricated, except that bearings
lubricated with non-toxic approved food-grade lubricants may be permitted in
wells where water-lubricated bearings are not feasible due to depth to the
water;
(ii) Where turbine pumps are
installed, the top of the casing shall be sealed into the pump motor. Where
submersible pumps are installed, the top of the casing shall be provided with a
watertight sanitary seal;
(iii) A
casing vent shall be provided and shall be fitted with a screened return
bend;
(iv) Provisions shall be made
for determining the depth to water surface in the well under pumping and static
conditions;
(v) A sampling tap
shall be provided on the pump discharge line;
(vi) Piping arrangements shall include
provisions for pumping the total flow from the well to waste;
(vii) A method of determining the total
output of each well shall be provided. This requirement may be waived by the
Authority at confined wells which serve as the source of supply for
TNCs;
(viii) A reinforced concrete
slab shall be poured around the well casing at ground surface. The slab shall
be sloped to drain away from the casing;
(ix) The ground surface around the well slab
shall be graded so that drainage is away from the well;
(x) The top of the well casing shall extend
at least 12 inches above the concrete slab;
(xi) Provisions shall be made for protecting
pump controls and other above-ground appurtenances at the well head. Where a
wellhouse is installed for this purpose, it shall meet applicable building
codes and shall be insulated, heated and provided with lights, except that
where the wellhouse consists of a small removable box-like structure the
requirement for lights may be waived by the Authority;
(xii) The wellhouse shall be constructed so
that the well pump can be removed.
(xiii) Wells equipped with pitless adaptors
or units are not required to meet the requirements of subparagraphs
(2)(a)(K)(iii) and (viii) of this rule.
(L) The area in the vicinity of a well,
particularly the area uphill or upstream, shall be surveyed by the water
supplier to determine the location and nature of any existing or potential
public health hazards;
(M) The
requirements with respect to land ownership, clearances from public health
hazards, and protection against flooding for wells in an unconfined aquifer
shall be the same or more restrictive than those prescribed for wells in
confined aquifers, as determined by the Authority.
(N) Before a well is placed into operation as
the source of supply for a public water system, the following documents shall
be submitted by the water supplier:
(i)
Reports on pumping tests for yield and drawdown for unconfined wells;
(ii) Reports of laboratory analyses on
contaminants in the water as required by OAR 333-061-0036;
(iii) Performance data on the pumps and other
equipment;
(iv) Proposals for
disinfection as required by section (5) of this rule, if applicable.
(v) Reports on determination of potential
direct influence by surface water into groundwater source as prescribed in
section (3) of this rule.
(b) Springs:
(A) In addition to those requirements under
subsection (2)(a) of this rule, construction of spring supplies shall meet the
following requirements:
(i) An intercepting
ditch shall be provided above the spring to effectively divert surface
water;
(ii) A fence shall be
installed around the spring area unless other provisions are made to
effectively prevent access by animals and unauthorized persons;
(iii) The springbox shall be constructed of
concrete or other impervious durable material and shall be installed so that
surface water is excluded;
(iv) The
springbox shall be provided with a screened overflow which discharges to
daylight, an outlet pipe provided with a shutoff valve, a bottom drain, an
access manhole with a tightly fitting cover, and a curb around the
manhole.
(v) Spring collection
facilities that meet the definition of a well in paragraph (2)(a)(A) of this
rule must comply with construction requirements specified in paragraph
(2)(a)(H) of this rule.
(B) Reports on flow tests shall be provided
to establish the yield of springs.
(3) Surface water and groundwater under
direct surface water influence source facilities:
(a) In selecting a site for an infiltration
gallery, or for a direct intake from a stream, lake, or impounding reservoir,
consideration shall be given to land use in the watershed. A sanitary survey of
the watershed shall be made by the water supplier to evaluate natural and
man-made factors which may affect water quality and investigations shall also
be made of seasonal variations in water quality and quantity. A report giving
the results of this survey shall be submitted for review and approval by the
Authority.
(b) A determination
shall be made as to the status of water rights, and this information shall be
submitted to the Authority for review.
(c) Impounding reservoirs shall be designed
and constructed so that they include the following features:
(A) The capacity shall be sufficient to meet
projected demands during drought conditions;
(B) Outlet piping shall be arranged so that
water can be withdrawn from various depths;
(C) Facilities shall be provided for
releasing undesirable water.
(d) Direct intake structures shall be
designed and constructed so that they include the following features:
(A) Screens shall be provided to prevent
fish, leaves and debris from entering the system;
(B) Provisions shall be made for cleaning the
screens, or self-cleaning screens shall be installed;
(C) Motors and electrical controls shall be
located above flood level;
(D)
Provisions shall be made to restrict swimming and boating in the vicinity of
the intake;
(E) Valves or sluice
gates shall be installed at the intake to provide for the exclusion of
undesirable water when required.
(4) Water treatment facilities (other than
disinfection):
(a) General:
(A) Water treatment facilities shall be
capable of producing water which consistently does not exceed MCLs. The type of
treatment shall depend on the raw water quality. The Authority shall make
determinations of treatment capabilities based upon recommendations in the US
EPA Guidance Manual for Compliance with the Filtration and Disinfection
Requirements for Public Water Systems Using Surface Water Sources.
(B) Investigations shall be undertaken by the
water supplier prior to the selection or installation of treatment facilities
to determine the physical, chemical and microbiological characteristics of the
raw water as appropriate. These investigations shall include a determination of
the seasonal variations in water quality, as well as a survey to identify
potential sources of contamination which may affect the quality of the raw
water.
(C) Water obtained from
wells constructed in conformance with the requirements of these rules and which
is found not to exceed the MCLs, may be used without treatment at public water
systems;
(D) Laboratory equipment
shall be provided so that the water supplier can perform analyses necessary to
monitor and control the treatment processes.
(E) Sampling taps shall be provided before
and following the treatment process and before the first user when any form of
water treatment is used at a public water system.
(b) Best Available Technology:
(A) Pilot studies or other supporting data
shall be used to demonstrate the effectiveness of any treatment method other
than that defined as a BAT. Pilot study protocol shall be approved beforehand
by the Authority. When point-of-use (POU) or point-of-entry (POE) devices are
used for compliance, programs to ensure proper long-term operation,
maintenance, and monitoring shall be provided by the water system to ensure
adequate performance.
(B) The
Authority identifies the following as the BAT, treatment techniques, or other
means available for achieving compliance with the MCLs for volatile organic
chemicals:
(i) Central treatment using packed
tower aeration for all these chemicals.
(ii) Central treatment using GAC for all
these chemicals except vinyl chloride.
(C) The Authority identifies the following as
the BAT, treatment techniques or other means generally available for achieving
compliance with the MCL for fluoride.
(i)
Activated alumina absorption, centrally applied.
(ii) Reverse osmosis, centrally
applied.
(D) The
Authority identifies the following as the BAT, treatment techniques, or other
means available for achieving compliance with the MCL for E.
coli as specified in OAR 333-061-0030(4).
(i) Protection of wells from fecal
contamination by appropriate placement and construction.
(ii) Maintenance of a disinfectant residual
throughout the distribution system.
(iii) Proper maintenance of the distribution
system including appropriate pipe replacement and repair procedures, main
flushing programs, proper operation and maintenance of storage tanks and
reservoirs, cross connection control and maintaining a minimum pressure of 20
psi at all service connections.
(iv) Filtration treatment or disinfection of
surface water or GWUDI or disinfection of groundwater using strong oxidants
such as chlorine, chlorine dioxide, or ozone.
(v) For systems using only groundwater,
compliance with the requirements of an Authority approved wellhead protection
program.
(E) The
Authority identifies the following as the BAT, treatment techniques, or other
means available for achieving compliance with the MCLs for organic chemicals.
(i) Central treatment using packed tower
aeration for Dibromochloropropane, Ethylene Dibromide,
Hexachlorocyclopentadiene and Di(2-ethylhexyl)adipate.
(ii) Central treatment using GAC for all
these chemicals except Trihalomethanes and Glyphosate.
(iii) Central treatment using oxidation
(chlorination or ozonation) for Glyphosate.
(F) The Authority identifies the following as
the BAT, treatment techniques, or other means available for achieving
compliance with the MCLs for inorganic chemicals. Preoxidation may be required
to convert Arsenic III to Arsenic V.
(i)
Central treatment using coagulation/filtration for systems with 500 or more
service connections for Antimony, Arsenic V (for systems with populations
501-10,000), Asbestos, Beryllium, Cadmium, Chromium, Mercury (influent
concentration >= 10ug/L), and Selenium (Selenium IV only).
(ii) Central treatment using direct and
diatomite filtration for Asbestos.
(iii) Central treatment using GAC for
Mercury.
(iv) Central treatment
using activated alumina for Arsenic V (for systems with populations l0,000 or
less), Beryllium, Selenium and Thallium.
(v) Central treatment using ion exchange for
Arsenic V (for systems with populations 10,000 or less), Barium, Beryllium,
Cadmium, Chromium, Cyanide, Nickel, Nitrate, Nitrite and Thallium.
(vi) Central treatment using lime softening
for systems with 500 or more service connections for Arsenic V (for systems
with populations of 501-10,000), Barium, Beryllium, Cadmium, Chromium (Chromium
III only), Mercury (influent concentration >= 10ug/L), Nickel and
Selenium.
(vii) Central treatment
using reverse osmosis for Antimony, Arsenic V (for systems with populations of
501-10,000), Barium, Beryllium, Cadmium, Chromium, Cyanide, Mercury (influent
concentration >= 10ug/L), Nickel, Nitrate, Nitrite, and Selenium.
(viii) Central treatment using corrosion
control for Asbestos and Lead and Copper.
(ix) Central treatment using electrodialysis
for Arsenic V (for systems with populations of 501-10,000), Barium, Nitrate,
and Selenium.
(x) Central treatment
using alkaline chlorination (pH>=8.5) for Cyanide.
(xi) Central treatment using
coagulation-assisted microfiltration for Arsenic V (for systems with
populations 501-10,000).
(xii)
Central treatment using oxidation/filtration for Arsenic V (to obtain high
removals, iron to Arsenic ratio must be at least 20:1).
(xiii) Point-of-use treatment using activated
alumina for Arsenic V (for systems with populations 10,000 or less).
(xiv) Point-of-use treatment using reverse
osmosis for Arsenic V (for systems with populations 10,000 or less).
(G) The Authority identifies the
following as the best technology, treatment techniques, or other means
available for achieving compliance with the MCLs for disinfection byproducts:
(i) For bromate concentrations: control of
ozone treatment process to reduce production of bromate.
(ii) For chlorite concentrations: control of
treatment processes to reduce disinfectant demand and control of disinfection
treatment processes to reduce disinfectant levels.
(iii) For TTHM and HAA5, for water systems
that disinfect their source water and monitor in accordance with OAR
333-061-0036(4)(c) or (d): enhanced coagulation or enhanced softening plus GAC
in filter beds with an empty-bed contact time of 10 minutes based on average
daily flow and a carbon reactivation frequency of every 180 days, except that
the reactivation frequency for GAC for compliance with OAR 333-061-0030(2)(b)
shall be 120 days; or nanofiltration with a molecular weight cutoff less than
or equal to 1000 Daltons; or GAC in filter beds with an empty-bed contact time
of 20 minutes based on average daily flow and a carbon reactivation frequency
of every 240 days.
(iv) For TTHMs
and HAA5, for purchasing water systems with populations greater than or equal
to 10,000 and that monitor in accordance with OAR 333-061-0036(4)(c) or (d)
improved distribution system and storage tank management to reduce residence
time, plus the use of chloramines for disinfectant residual maintenance. This
applies only to the disinfected water that purchasing water systems receive
from a wholesale system.
(v) For
TTHMs and HAA5, for purchasing water systems with populations less than 10,000
and that monitor in accordance with OAR 333-061-0036(4)(c) or (d): improved
distribution system and storage tank management to reduce residence time. This
applies only to the disinfected water that purchasing water systems receive
from a wholesale system.
(H) The Authority identifies the following as
the best technology, treatment techniques, or other means available for
achieving compliance with the MRDLs: Control of treatment processes to reduce
disinfectant demand and control of disinfection treatment processes to reduce
disinfectant levels.
(I) The
Authority identifies the following as the BAT, treatment techniques, or other
means available for achieving compliance with the MCLs for radionuclides.
(i) Central treatment using ion exchange for
combined radium-226/228, beta particle/photon activity and uranium.
(ii) Central treatment using reverse osmosis
for combined radium-226/228, gross alpha particle activity, beta
particle/photon activity, and uranium (for systems with populations
501-10,000).
(iii) Central
treatment using lime softening for combined radium-226/228, and uranium (for
systems with populations 501-10,000).
(iv) Central treatment using enhanced
coagulation/filtration for uranium.
(v) Central treatment using activated alumina
for uranium (for systems with populations of 10,000 or less).
(vi) Central treatment using greensand
filtration for combined radium-226/228.
(vii) Central treatment using electrodialysis
for combined radium-226/228.
(viii)
Central treatment using pre-formed hydrous manganese oxide filtration for
combined radium-226/228.
(ix)
Central treatment using co-precipitation with barium for combined
radium-226/228.
(x) Point-of-use
treatment using ion exchange for combined radium-226/228, beta particle/photon
activity, and uranium.
(xi)
Point-of use treatment using reverse osmosis for combined radium-226/228, gross
alpha particle activity, beta particle/ photon activity, and uranium (for
systems with populations of 10,000 or less).
(c) Filtration of Surface Water Sources and
Groundwater Sources Under the Direct Influence of Surface Water.
(A) All water systems using surface water or
groundwater sources under the direct influence of surface water that fail to
meet the criteria for avoiding filtration prescribed in OAR 33-061-0032(2) and
(3) must meet all requirements of this subsection for installing filtration
treatment.
(B) There are four
standard filtration methods: conventional filtration, direct filtration, slow
sand, and diatomaceous earth. Other filtration technologies are only acceptable
if their efficiency at removing target organisms and contaminants can be
demonstrated to be equal to or more efficient than these. The assumed log
removals credited to filtration of Giardia lamblia and viruses
will be based on recommendations in the US EPA Guidance Manual for Compliance
with the Filtration and Disinfection Requirements for Public Water Systems
Using Surface Water Sources. In all cases, filtration processes must be
designed and operated to achieve at least 2.0 log removal of Giardia
lamblia. For membrane filtration, removal credits shall be verified by
a challenge study according to paragraphs (4)(c)(H) and (I) of this rule. Bag
and Cartridge Filtration must have removal credits demonstrated in a challenge
study according to paragraph (4)(c)(J) of this rule. The combination of
filtration and disinfection must meet the inactivation levels prescribed in OAR
333-061-0032(1). Any water system wishing to challenge the assumed log removal
credits must conduct demonstration studies based on the recommendations in the
USEPA SWTR Guidance Manual and have the study protocol approved by the
Authority.
(C) Pilot studies shall
be conducted by the water supplier to demonstrate the effectiveness of any
filtration method other than conventional filtration. Pilot study protocol
shall be approved in advance by the Authority. Results of the pilot study shall
be submitted to the Authority for review and approval.
(D) Regardless of the filtration method used,
the water system must achieve a minimum of 0.5-log reduction of Giardia
lamblia and a 1.0-log reduction of viruses from disinfection alone
after filtration treatment.
(E) All
filtration systems shall be designed and operated so as to meet the
requirements prescribed in OAR 333-061-0032(4) and (5). Design of the
filtration system must be in keeping with accepted standard engineering
references acknowledged by the Authority such as the Great Lakes Upper
Mississippi River "Recommended Standards for Water Works" technical reports by
the International Reference Center for Community Water Supply and Sanitation,
or publications from the World Health Organization. A list of additional
references is available from the Authority upon request.
(F) Requirements for water systems using
conventional or direct filtration.
(i)
Systems that employ multiple filters shall be designed such that turbidity
measurements are monitored for each filter independently of the other
filter(s). Each filter shall have a provision to discharge effluent water as
waste.
(ii) All water treatment
plants shall have an auto-dial call out alarm or an automatic shut-off for high
turbidity.
(G)
Additional requirements for membrane filtration. Each membrane filter system
must have a turbidimeter installed after each filter unit for continuous
indirect integrity monitoring. Once operating, direct and indirect integrity
testing must be conducted on each unit as described in OAR 333-061-0036(5)(d).
The operation and maintenance manual must include a diagnosis and repair plan
such that the ability to remove pathogens is not compromised.
(H) Challenge Study criteria for Membrane
Filtration. Water systems receive Cryptosporidium treatment
credit for membrane filtration, as defined in OAR 333-061-0020(59)(f), that
meets the criteria of this paragraph. The level of treatment credit a water
system receives is equal to the lower of the values determined in this
paragraph.
(i) The removal efficiency
demonstrated during challenge testing conducted under the conditions in
accordance with paragraph (4)(c)(I) of this rule.
(ii) The maximum removal efficiency that can
be verified through direct integrity testing of the membrane filtration process
under the conditions prescribed by OAR 333-061-0036(5)(d)(B).
(I) Challenge Testing. The
membrane filter used by the water system must undergo challenge testing to
evaluate removal efficiency, and results of the challenge testing must be
reported to the Authority. Challenge testing must be conducted according to the
criteria specified in this paragraph. Water systems may use data from challenge
testing conducted prior to June 1, 2009 if the prior testing was consistent
with the criteria specified in this paragraph.
(i) Challenge testing must be conducted on a
full-scale membrane module, identical in material and construction to the
membrane modules used in the water system's treatment facility, or a
smaller-scale membrane module, identical in material and similar in
construction to the full-scale module. A module is defined as the smallest
component of a membrane unit in which a specific membrane surface area is
housed in a device with a filtrate outlet structure.
(ii) Challenge testing must be conducted
using Cryptosporidium oocysts or a surrogate that is removed
no more efficiently than Cryptosporidium oocysts.
Cryptosporidium or the surrogate used during challenge testing
is referred to as the challenge particulate. The concentration of the challenge
particulate, in both the feed and filtrate water, must be determined using a
method capable of discretely quantifying the specific challenge particulate
used in the test; gross measurements such as turbidity may not be
used.
(iii) The maximum feed water
concentration that can be used during a challenge test is based on the
detection limit of the challenge particulate in the filtrate and must be
determined according to the following equation:
Maximum Feed Concentration = 3.16 x 106 x (Filtrate Detection Limit).
(iv) Challenge
testing must be conducted according to representative hydraulic conditions at
the maximum design flux and maximum design process recovery specified by the
manufacturer for the membrane module. Flux is defined as the throughput of a
pressure driven membrane process expressed as flow per unit of membrane area.
Recovery is defined as the volumetric percent of feed water that is converted
to filtrate over the course of an operating cycle uninterrupted by events such
as chemical cleaning or a solids removal process (that is,
backwashing).
(v) Removal
efficiency of a membrane module must be calculated from the challenge test
results and expressed as a log removal value according to the following
equation:
LRV = LOG10(Cf) - LOG10(Cp)
Where:
LRV = log removal value demonstrated during the challenge test;
Cf = the feed concentration measured during the challenge test; and
Cp = the filtrate concentration measured during the challenge test. Equivalent units must be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, the term Cp is set equal to the detection limit for the purpose of calculating the LRV. An LRV must be calculated for each membrane module evaluated during the challenge test.
(vi) The removal
efficiency of a membrane filtration process demonstrated during challenge
testing must be expressed as a log removal value (LRVC-Test). If fewer than 20
modules are tested, then LRVC-Test is equal to the lowest of the representative
LRVs among the modules tested. If 20 or more modules are tested, then LRVC-Test
is equal to the 10th percentile of the representative LRVs among the modules
tested. The percentile is defined by (i/(n+1)) where i is the rank of n
individual data points ordered lowest to highest. If necessary, the 10th
percentile may be calculated using linear interpolation.
(vii) The challenge test must establish a
quality control release value (QCRV) for a non-destructive performance test
that demonstrates the Cryptosporidium removal capability of
the membrane filtration module. This performance test must be applied to each
production membrane module used by the system that was not directly challenge
tested in order to verify Cryptosporidium removal capability.
Production modules that do not meet the established QCRV are not eligible for
the treatment credit demonstrated during the challenge test.
(viii) If a previously tested membrane is
modified in a manner that could change the removal efficiency of the membrane
or the applicability of the non-destructive performance test and associated
QCRV, additional challenge testing to demonstrate the removal efficiency of,
and determine a new QCRV for, the modified membrane must be conducted and
submitted to the Authority.
(J) Challenge Study requirements for Bag and
Cartridge Filtration.
(i) The
Cryptosporidium treatment credit awarded to bag or cartridge
filters must be based on the removal efficiency demonstrated during challenge
testing that is conducted according to the criteria specified in this
paragraph. A factor of safety equal to 1-log for individual bag or cartridge
filters and 0.5-log for bag or cartridge filters in series must be applied to
challenge testing results to determine removal credit. Water systems may use
results from challenge testing conducted prior to June 1, 2009 if the prior
testing was consistent with the criteria specified in this paragraph.
(ii) Challenge testing must be performed on
full-scale bag or cartridge filters and the associated filter housing or
pressure vessel, that are identical in material and construction to the filters
and housings the water system will use for removal of
Cryptosporidium. Bag or cartridge filters must be challenge
tested in the same configuration that the system will use, either as individual
filters or as a series configuration of filters.
(iii) Challenge testing must be conducted
using Cryptosporidium or a surrogate that is removed no more
efficiently than Cryptosporidium. The microorganism or
surrogate used during challenge testing is referred to as the challenge
particulate. The concentration of the challenge particulate must be determined
using a method capable of discreetly quantifying the specific microorganism or
surrogate used in the test; gross measurements such as turbidity may not be
used.
(iv) The maximum feed water
concentration that can be used during a challenge test must be based on the
detection limit of the challenge particulate in the filtrate (that is, filtrate
detection limit) and must be calculated using the following equation:
Maximum Feed Concentration = 1 x 104 x (Filtrate Detection Limit).
(v) Challenge
testing must be conducted at the maximum design flow rate for the filter as
specified by the manufacturer.
(vi)
Each filter evaluated must be tested for a duration sufficient to reach 100
percent of the terminal pressure drop, which establishes the maximum pressure
drop under which the filter may be used to comply with the requirements of this
paragraph.
(vii) Removal efficiency
of a filter must be determined from the results of the challenge test and
expressed in terms of log removal values using the following equation:
LRV = LOG10(Cf)-LOG10(Cp).
Where:
LRV = log removal value demonstrated during challenge testing;
Cf = the feed concentration measured during the challenge test; and
Cp = the filtrate concentration measured during the challenge test. In applying this equation, the same units must be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, then the term Cp must be set equal to the detection limit.
(viii) Each filter tested must be
challenged with the challenge particulate during three periods over the
filtration cycle: within two hours of start-up of a new filter; when the
pressure drop is between 45 and 55 percent of the terminal pressure drop; and
at the end of the cycle after the pressure drop has reached 100 percent of the
terminal pressure drop. An LRV must be calculated for each of these challenge
periods for each filter tested. The LRV for the filter (LRVfilter) must be
assigned the value of the minimum LRV observed during the three challenge
periods for that filter.
(ix) If
fewer than 20 filters are tested, the overall removal efficiency for the filter
product line must be set equal to the lowest LRVfilter among the filters
tested. If 20 or more filters are tested, the overall removal efficiency for
the filter product line must be set equal to the 10th percentile of the set of
LRVfilter values for the various filters tested. The percentile is defined by
(i/(n+1)) where i is the rank of n individual data points ordered lowest to
highest. If necessary, the 10th percentile may be calculated using linear
interpolation.
(x) If a previously
tested filter is modified in a manner that could change the removal efficiency
of the filter product line, challenge testing to demonstrate the removal
efficiency of the modified filter must be conducted and submitted to the
Authority.
(K) Water
systems using cartridge filtration must have pressure gauges installed before
and after each cartridge filter.
(L) Water systems using diatomaceous earth
filtration must add the body feed with the influent flow.
(d) Criteria and procedures for public water
systems using point-of-entry (POE) or point-of-use (POU) devices.
(A) Public water systems may use POE or POU
devices to comply with MCLs, where specified in subsection (4)(b) of this rule,
only if they meet the requirements of this subsection.
(B) It is the responsibility of the public
water system to operate and maintain the POE or POU treatment system.
(C) The public water system must develop and
obtain Authority approval for a monitoring plan before POE or POU devices are
installed for compliance. Under the plan approved by the Authority, POE or POU
devices must provide health protection equivalent to central water treatment.
"Equivalent" means that the water would meet all MCLs as prescribed in OAR
333-061-0030 and would be of acceptable quality similar to water distributed by
a well-operated central treatment plant. Monitoring must include contaminant
removal efficacy, physical measurements and observations such as total flow
treated and mechanical condition of the treatment equipment.
(D) Effective technology must be properly
applied under a plan approved by the Authority and the microbiological safety
of the water must be maintained.
(i) The water
supplier must submit adequate certification of performance, field testing, and,
if not included in the certification process, a rigorous engineering design
review of the POE or POU devices to the Authority for approval prior to
installation.
(ii) The design and
application of the POE or POU devices must consider the tendency for increase
in heterotrophic bacteria concentrations in water treated with activated
carbon. It may be necessary to use frequent backwashing, post-contractor
disinfection, and Heterotrophic Plate Count monitoring to ensure that the
microbiological safety of the water is not compromised.
(iii) The POE or POU device must be evaluated
to assure that the device will not cause increased corrosion of lead and copper
bearing materials located between the device and the tap that could increase
contaminant levels of lead and copper at the tap.
(E) All consumers shall be protected. Every
building connected to the system must have a POE or POU device installed,
maintained, and adequately monitored. The Authority must be assured that every
building is subject to treatment and monitoring, and that the rights and
responsibilities of the public water system customer convey with title upon
sale of property.
(5) Facilities for disinfection and
disinfectant residual maintenance:
(a) Water
obtained from surface sources or groundwater sources under the direct influence
of surface water shall, as a minimum, be provided with disinfection for
pathogen inactivation before such water may be used as a source of supply for a
public water system. Water obtained from wells constructed in conformance with
the requirements of these rules and which is found not to exceed
microbiological MCLs, may be used without treatment at public water
systems;
(b) Water obtained from
wells and springs shall be considered groundwater unless determined otherwise
by the Authority. Wells and springs may be utilized without disinfection if the
construction requirements of section (2) of this rule are met and analyses
indicate that the water consistently meets microbiological standards. A well or
spring that is inadequately constructed must be upgraded to meet current
construction standards or disconnected from the water system before
disinfection treatment may be utilized when E. coli
contamination was confirmed according to OAR 333-061-0032(7) or OAR
333-061-0036(6)(j) and where the Authority determines that reconstruction will
add a significant measure of public health protection.
(c) In public water systems where
disinfection for pathogen inactivation is required as the sole form of
treatment or as one component of more extensive treatment to meet the
requirements prescribed in OAR 333-061-0032(1), the facilities shall be
designed so that:
(A) The disinfectant
applied shall be capable of effectively destroying pathogenic
organisms;
(B) The disinfectant is
applied in proportion to water flow; and
(C) Disinfectants, other than ultraviolet
light (UV) and ozone, shall be capable of leaving a residual in the water which
can be readily measured and which continues to serve as an active disinfectant.
The disinfectant shall be applied at every entry point so a residual is present
throughout the distribution system; and
(D) Sufficient contact time shall be provided
to achieve "CT" values capable of the inactivation required by OAR
333-061-0032(1). For UV disinfection treatment, sufficient irradiance expressed
in milliwatts per square centimeter (mWs/cm2) and exposure time expressed in
seconds shall be provided to achieve UV dose levels expressed as (mWs/cm2) or
millijoules per square centimeter (mJ/cm2) capable of the inactivation required
by OAR 333-061-0032(1).
(d) When disinfection for pathogen
inactivation, other than UV disinfection, is required for reasons other than
the treatment of surface water sources or groundwater sources under the direct
influence of surface water, in addition to the requirements of paragraphs
(5)(c)(A) through (C) of this rule, the facilities shall be designed so that:
(A) The primary disinfection treatment is
sufficient to ensure at least 99.99 percent (4-log) inactivation or removal of
viruses as determined by the Authority, or;
(B) There is sufficient contact time provided
to achieve disinfection under all flow conditions between the point of
disinfectant application and the point of first water use:
(i) When chlorine is used as the primary
disinfectant, the system shall be constructed to achieve a free chlorine
residual of 0.2 mg/l after 30 minutes contact time under all flow conditions
before first water use;
(ii) When
ammonia is added to the water with the chlorine to form a chloramine as the
disinfectant, the system shall be constructed to achieve a combined chlorine
residual of at least 2.0 mg/l after three hours contact time under all flow
conditions before first water use;
(e) Provisions shall be made to alert the
water supplier before the chlorine supply is exhausted. Water systems serving
more than 3,300 people shall have an auto-dial call out alarm or an automatic
shut-off for low chlorine residual when chlorine is used as a
disinfectant.
(f) Sample taps shall
be provided before and after disinfectant application as specified in
subsection (4)(a)(E) of this rule;
(g) Testing equipment shall be provided to
determine the chlorine residual;
(h) Chlorinator piping shall be designed to
prevent the contamination of the potable water system by backflow of untreated
water or water having excessive concentrations of chlorine;
(i) The disinfectant must be applied in
proportion to water flow;
(j)
Chlorine gas feeders and chlorine gas storage areas shall:
(A) Be enclosed and separated from other
operating areas;
(B) Chlorine
cylinders shall be restrained in position to prevent upset by chaining 100 and
150 pound cylinders two-thirds of their height up from the floor and by double
chocking one ton cylinders;
(C) The
room housing the feeders and cylinders shall be above ground surface, shall
have doors which open outward and to the outside and shall be ventilated by
mechanical means at floor level and shall have an air intake located higher
than the exhaust ventilation;
(D)
Be located so that chlorine gas, if released, will not flow into the building
ventilation systems;
(E) Have
corrosion resistant lighting and ventilation switches located outside the
enclosure, adjacent to the door;
(F) Be provided with a platform or hydraulic
scale for measuring the weight of the chlorine cylinders;
(G) Be provided with a gas mask or
self-contained breathing apparatus approved by the National Institute of
Occupational Safety and Health (NIOSH) for protection against chlorine gas and
kept in good working condition. Storage of such equipment shall be in an area
adjoining the chlorine room and shall be readily available. (Also see the
Oregon Occupational Health and Safety regulations contained in OAR chapter
437.)
(k) When
disinfection for pathogen inactivation is provided through UV disinfection, the
facilities shall be designed to meet the requirements of this subsection:
(A) The UV unit must achieve the dosage
indicated in Table 32 for the required pathogen inactivation.
(B) Ultraviolet lamps are insulated from
direct contact with the influent water and are removable from the lamp
housing;
(C) The treatment unit
must have an upstream valve or device that prevents flows from exceeding the
manufacturer's maximum rated flow rate, a UV sensor that monitors light
intensity through the water during operation, and a visual and audible
alarm;
(D) There must be a visual
means to verify operation of all ultraviolet lamps;
(E) The lamps, lamp sleeves, housings and
other equipment must be able to withstand the working pressures applied through
the unit;
(F) The treatment
facility must be sheltered from the weather and accessible for routine
maintenance as well as routine cleaning and replacement of the lamp sleeves and
cleaning of the sensor windows/lenses;
(G) The lamps must be changed as per the
manufacturer's recommendation; and
(H) The treatment unit must have shut-off
valves at both the inlet side and the outlet side of the treatment unit. There
shall be no bypass piping around the treatment unit.
(I) Reactor validation testing. All water
systems, except those specified in paragraph (5)(l) of this rule, must use UV
reactors that have undergone validation testing to determine the operating
conditions under which the reactor delivers the UV dose required in OAR
333-061-0036(5)(c) (that is, validated operating conditions). These operating
conditions must include flow rate, UV intensity as measured by a UV sensor, UV
Transmittance based on reactor validation, and UV lamp status.
(i) When determining validated operating
conditions, water systems must account for the following factors: UV absorbance
by the water; lamp fouling and aging; measurement uncertainty of on-line
sensors; UV dose distributions arising from the velocity profiles through the
reactor; failure of UV lamps or other critical system components; and inlet and
outlet piping or channel configurations of the UV reactor.
(ii) Validation testing must include the
following: full scale testing of a reactor that conforms uniformly to the UV
reactors used by the water system and inactivation of a test microorganism
whose dose response characteristics have been quantified with a low pressure
mercury vapor lamp.
(iii) The
Authority may approve an alternative approach to validation testing.
(l) At non-Community
water systems using only groundwater sources and having minimal distribution
systems as determined by the Authority, water suppliers may use UV as the only
disinfectant when total coliforms but no E. coli have been
detected in the source water. UV units must meet the specifications of a Class
A UV system according to NSF Standard 55.
(6) Finished water storage:
(a) Distribution reservoirs and treatment
plant storage facilities for finished water shall be constructed to meet the
following requirements:
(A) They shall be
constructed of concrete, steel, wood or other durable material capable of
withstanding external and internal forces which may act upon the
structure;
(B) Ground-level
reservoirs shall be constructed on undisturbed soil, bedrock or other stable
foundation material capable of supporting the structure when full;
(C) Steel reservoirs, standpipes and elevated
tanks shall be constructed in conformance with the AWWA Standards D100 and
D103;
(D) Concrete reservoirs shall
be provided with sufficient reinforcing to prevent the formation of cracks, and
waterstops and dowels shall be placed at construction joints. Poured-in-place
wall castings shall be provided where pipes pass through the
concrete;
(E) Wooden reservoirs
shall be redwood or other equally durable wood and shall be installed on a
reinforced concrete base. Where redwood reservoirs are used, separate inlet and
outlet pipes are required and the water entering the reservoir must have a
disinfectant continuously applied so as to result in a detectable residual in
the water leaving the reservoir;
(F) Start-up procedures for new redwood tanks
shall consist of filling the tank with a solution of water containing a minimum
of two pounds of sodium carbonate per 1,000 gallons of water and retaining this
solution in the tank a minimum of seven days before flushing;
(G) Where ground-level reservoirs are located
partially below ground, the bottom shall be above the ground water table and
footing drains discharging to daylight shall be provided to carry away ground
water which may accumulate around the perimeter of the structure;
(H) The finished water storage capacity shall
be increased to accommodate fire flows when fire hydrants are
provided;
(I) Finished water
storage facilities shall have watertight roofs;
(J) An access manhole shall be provided to
permit entry to the interior for cleaning and maintenance. When the access
manhole is on the roof of the reservoir there shall be a curbing around the
opening and a lockable watertight cover that overlaps the curbing;
(K) Internal ladders of durable material,
shall be provided where the only access manhole is located on the
roof;
(L) Screened vents shall be
provided above the highest water level to permit circulation of air above the
water in finished water storage facilities;
(M) A drain shall be provided at the lowest
point in the bottom of the storage facility and an overflow of sufficient
diameter to handle the maximum flow into the tank shall be provided at or near
the top of the sidewall. The outlet ends of the drain and overflow shall be
fitted with angle-flap valves or equivalent protection and shall discharge to a
watercourse or storm drain capable of accommodating the flow with a vertical
separation between the bottom of the pipe and top of the receiving body or
structure;
(N) A silt stop shall be
provided at the outlet pipe;
(O)
Where a single inlet/outlet pipe is installed and the reservoir floats on the
system, provisions shall be made to insure an adequate exchange of water and to
prevent degradation of the water quality and to assure the disinfection levels
required in subparagraph (5)(c)(D) of this rule;
(P) A fence or other method of vandal
deterrence shall be provided around distribution reservoirs;
(Q) When interior surfaces of finished water
storage tanks are provided with a protective coating, the coating shall meet
the requirements of NSF Standard 61: Drinking Water System Components - Health
Effects or equivalent.
(R)
Reservoirs and clearwells that are to be used for disinfection contact time to
treat surface water shall use a tracer study to determine the actual contact
time. The Authority must approve procedures and protocols for the tracer study
prior to the initiation of the study. The Authority recommends the US EPA
Guidance Manual for Compliance with the Filtration and Disinfection
Requirements for Public Water Systems Using Surface Water Sources for a tracer
study procedure and protocol.
(S)
Reservoirs and clearwells that are to be used for disinfection contact time to
treat surface water shall have a means to adequately determine the flow rate on
the effluent line.
(b)
Pressure tanks for finished water shall meet the following requirements:
(A) Pressure tanks shall be installed above
normal ground surface;
(B) Bypass
piping around the pressure tank shall be provided to permit operation of the
system while the tank is being maintained or repaired;
(C) Pressure tanks greater than 1,000 gallons
shall be provided with an access manhole and a water sight-glass.
(D) All pressure tanks shall be provided with
a drain, a pressure gauge, an air blow-off valve, means for adding air and
pressure switches for controlling the operation of the pump(s);
(E) Pressure tanks shall be constructed of
steel or an alternative material provided the tank is NSF 61 certified and
shall be designed for pressure at least 50 percent greater than the maximum
system pressure anticipated.
(7) Pumping facilities:
(a) Wherever possible, booster pumps shall
take suction from tanks and reservoirs to avoid the potential for negative
pressures on the suction line which result when the pump suction is directly
connected to a distribution main;
(b) Pumps which take suction from
distribution mains for the purpose of serving areas of higher elevation shall
be provided with a low pressure cut-off switch on the suction side set at no
less than 20 psi;
(c) Suction lift
at pumping stations shall be avoided as far as possible, and pumps shall be
installed so that the suction line is under a positive head. If suction lift
cannot be avoided, provision shall be made for priming with water which does
not exceed MCLs;
(d) Pumping
stations shall be located above maximum anticipated 100-year (1 percent) flood
level, and the area around the pumping station shall be graded so that surface
drainage is away from the station;
(e) Pumping stations shall be of durable
construction so as to protect the equipment from the elements. The door to the
pumping station shall be lockable, and facilities for heating and lighting
shall be provided. The floor of the pumping station shall be sloped to provide
adequate drainage.
(8)
Distribution systems:
(a) Wherever possible,
distribution pipelines shall be located on public property. Where pipelines are
required to pass through private property, easements shall be obtained from the
property owner and shall be recorded with the county clerk;
(b) Pipe, pipe fittings, valves and other
appurtenances utilized at Community water systems shall be manufactured,
installed and tested in conformance with the latest standards of the American
Water Works Association, NSF International or other equivalent standards
acceptable to the Authority;
(c) In
Community water systems, distribution mains located in public roadways or
easements, and the portion of the service connections from the distribution
main to the customer's property line or service meter where provided are
subject to the requirements of these rules. The piping from the customer's
property line, or the meter where provided, to the point of water use (the
building supply line) is subject to the requirements of the State Plumbing
Code;
(d) In all Public Water
Systems where the system facilities and the premises being served are both on
the same parcel of property, requirements relating to pipe materials and pipe
installation shall comply with the State Plumbing Code;
(e) Distribution piping shall be designed and
installed so that the pressure measured at the property line in the case of
Community water systems, or at the furthest point of water use, in the case of
a TNC of the type described in subsection (d) of this section, shall not be
reduced below 20 psi;
(f)
Distribution piping shall be carefully bedded and fully supported in material
free from rocks and shall be provided with a cover of at least 30 inches.
Select backfill material shall be tamped in layers around and over the pipe to
support and protect it. Large rocks or boulders shall not be used as backfill
over the pipe;
(g) Provision shall
be made at all bends, tees, plugs, and hydrants to prevent movement of the pipe
or fitting;
(h) Wherever possible,
dead ends shall be minimized by looping. Where dead ends are installed, or low
points exist, blow-offs of adequate size shall be provided for
flushing;
(i) Air-relief valves
shall be installed at high points where air can accumulate. The breather tube
on air-relief valves shall be extended above ground surface and provided with a
screened, downward facing elbow;
(j) Yarn, oakum, lead or other material which
may impair water quality shall not be used where it will be in contact with
potable water;
(k) Nonconductive
water pipe (plastic or other material) that is not encased in conductive pipe
or casing must have an electrically conductive wire or other approved conductor
for locating the pipe when the pipeline is underground. The wire shall be No.
18 AWG (minimum) solid copper with blue colored insulation. Ends of wire shall
be accessible in water meter boxes, valve boxes or casings, or outside the
foundation of buildings where the pipeline enters the building. The distance
between tracer lead access locations shall not be more than 1,000 feet. Joints
or splices in wire shall be waterproof.
(l) Piping that is to be used for
disinfection contact time shall be verified by plug flow calculations under
maximum flow conditions. Plug flow, in this context, means the movement of
water in a pipe such that particles pass through the pipe and are discharged in
the same sequence in which they entered.
(9) Crossings-Sanitary sewers and water
lines:
(a) All reference to sewers in this
section shall mean sanitary sewers;
(b) In situations involving a water line
parallel to a sewer main or sewer lateral, the separation between the two shall
be as indicated in Figure 1;
(c) In
situations where a water line and a sewer main or sewer lateral cross, the
separation between the two shall be as follows:
(A) Wherever possible, the bottom of the
water line shall be 1.5 feet or more above the top of the sewer line and one
full length of the water line shall be centered at the crossing;
(B) Where the water line crosses over the
sewer line but with a clearance of less than 1.5 feet, the sewer line shall be
exposed to the sewer line joints on both sides of the crossing to permit
examination of the sewer pipe. If the sewer pipe is in good condition and there
is no evidence of leakage from the sewer line, the 1.5-foot separation may be
reduced. However, in this situation, the water supplier must center one length
of the water line at the crossing and must prepare a written report of the
findings and indicating the reasons for reducing the separation. If the water
supplier determines that the conditions are not favorable or finds evidence of
leakage from the sewer line, the sewer line shall be replaced with a full
length of pipe centered at the crossing point, of PVC pressure pipe (ASTM
D-2241, SDR 32.5), high-density PE pipe (Drisco pipe 1000), ductile-iron Class
50 (AWWA C-51), or other acceptable pipe; or the sewer shall be encased in a
reinforced concrete jacket for a distance of 10 feet on both sides of the
crossing.
(C) Where the water line
crosses under the sewer line, the water supplier shall expose the sewer line
and examine it as indicated in paragraph (9)(c)(B) of this rule. If conditions
are favorable and there is no evidence of leakage from the sewer line, the
sewer line may be left in place, but special precautions must be taken to
assure that the backfill material over the water line in the vicinity of the
crossing is thoroughly tamped in order to prevent settlement which could result
in the leakage of sewage. In this situation, the water supplier must center one
length of the water line at the crossing and must prepare a written report
recording the manner in which the sewer line was supported at the crossing and
the material and methods used in backfilling and tamping to prevent settlement
of the sewer. If the water supplier determines that conditions are not
favorable or finds evidence of leakage from the sewer line, the provisions of
paragraph (9)(c)(B) of this rule apply.
(d) When a water main is installed under a
stream or other watercourse, a minimum cover of 30 inches shall be provided
over the pipe. Where the watercourse is more than 15 feet wide, the pipe shall
be of special construction with flexible watertight joints, valves shall be
provided on both sides of the crossing so that the section can be isolated for
testing or repair, and test cocks shall be provided at the valves.
(10) Disinfection of facilities:
(a) Following construction or installation of
new facilities and repairs to existing facilities, those portions of the
facilities which will be in contact with water delivered to users must be
cleaned and flushed with potable water and disinfected according to AWWA
Standards C651 through C654 before they are placed into service. Disinfection
must be by chlorine unless another disinfectant can be demonstrated to be
equally effective.
(b) For
construction of new distribution pipelines (with any associated service
connections and other appurtenances installed at the time of construction),
disinfection by chlorination must be conducted as specified in paragraphs (A)
through (C) of this subsection unless another method from AWWA Standard C651 is
used.
(A) A solution with a free chlorine
residual of at least 25 mg/l must be introduced to the pipe such that the
solution will contact all surfaces and trapped air will be eliminated. The
solution must remain in place for at least 24 hours.
(B) After 24 hours, if the free chlorine
residual is 10 mg/l or greater, the chlorine solution must be drained and the
pipe flushed with potable water. If the free chlorine residual is less than 10
mg/l after 24-hours, the pipe must be flushed and rechlorinated until a free
chlorine residual of 10 mg/l or more is present after a 24 hour
period.
(C) After the pipe is
disinfected, flushed and filled with potable water, bacteriological samples
must be collected to determine the procedures' effectiveness. At least two
samples must be collected from the new pipe at least 16 hours apart and
analyzed for coliform bacteria. If the pipe has held potable water for at least
16 hours before sample collection, two samples may be collected at least 15
minutes apart while the sample tap is left running. If the results of both
analyses indicate the water is free of coliform bacteria, the pipe may be put
into service. If either sample indicates the presence of coliform bacteria, the
pipe may be re-flushed, filled with potable water and re-sampled. If this
second set of samples is free of coliform bacteria, the pipe may be put into
service, otherwise the disinfection and flushing process must be repeated until
samples are free of coliform.
(c) For repaired pipelines that were
depressurized and wholly or partly dewatered during repair or that likely
experienced contamination during repair, disinfection according to the
procedure specified in paragraphs (10)(b)(A) through (C) of this rule must be
followed except that bacteriological samples must be collected downstream of
the repair site. If the direction of flow is unknown, samples must be collected
on each side of the repair site.
(d) A water line may be returned to service,
following repairs or routine maintenance, prior to receiving a report on the
bacteriological analysis if the following procedures have been completed:
(A) Customer meters were shut off prior to
placing the water line out of service;
(B) The area below the water line to be
repaired was excavated and dewatered;
(C) The exposed pipe was treated with a
hypochlorite solution;
(D) The
water line was flushed thoroughly, and a concentration of residual chlorine has
been re-established that is comparable to the level normally maintained by the
water system, if applicable; and
(E) Bacteriological analysis was conducted to
verify repair effectiveness according to this section and samples were
collected downstream of the repair site or on each side of the repair site if
the direction of flow is unknown.
(e) For reservoirs and tanks, disinfection by
chlorination shall be accomplished according to AWWA Standard C652 which
includes, but is not limited to, the following methods:
(A) Filling the reservoir or tank and
maintaining a free chlorine residual of not less than 10 mg/l for the
appropriate 6 or 24 hour retention period; or
(B) Filling the reservoir or tank with a 50
mg/l chlorine solution and leaving for six hours; or
(C) Directly applying by spraying or brushing
a 200 mg/l solution to all surfaces of the storage facility in contact with
water if the facility were full to the overflow elevation.
(f) When the procedures described in
paragraphs (10)(e)(A) and (B) of this rule are followed, the reservoir or tank
shall be drained after the prescribed contact period and refilled with potable
water, and a sample taken for microbiological analysis. If the results of the
analysis indicate that the water is free of coliform organisms, the facility
may be put into service. If not, the procedure shall be repeated until a sample
free of coliform organisms is obtained;
(g) When the procedure described in paragraph
(10)(e)(C) of this rule is followed, the reservoir or tank shall be filled with
potable water and a sample taken for microbiological analysis. It will not be
necessary to flush the reservoir or tank after the chlorine solution is applied
by spraying or brushing. Microbiological analysis shall indicate that the water
is free of coliform organisms before the facility can be put into
service;
(h) When a reservoir is
chlorinated following routine maintenance, inspection, or repair, it may be put
back into service prior to receiving the report on the microbiological analysis
provided the water leaving the reservoir has a free chlorine residual of at
least 0.4 mg/l or a combined chlorine residual of at least 2.0 mg/l.
(i) Underwater divers used for routine
maintenance, inspection, or repair of reservoirs shall use a full body dry suit
with hardhat scuba and an external air supply. The diver shall be disinfected
by spraying a 200 mg/l solution of chlorine on all surfaces that will come into
contact with drinking water.
Notes
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Statutory/Other Authority: ORS 448.131
Statutes/Other Implemented: ORS 448.131, 448.150, 448.273 & 448.279
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