WAC 246-290-820
Distribution system leakage standard. (1) Municipal water suppliers shall determine distribution
system leakage annually under
subsection (2) of this section or an alternative methodology under subsection (3) of this section.
(a) Municipal water suppliers shall include (i), (ii), or
(iii) of this subsection in water use efficiency performance
reports developed under WAC 246-290-840 and water use
efficiency programs developed under WAC 246-290-810:
(i) Distribution system leakage totals calculated under subsection (2) of this section shall
be recorded in annual percent and volume;
(ii) Distribution system leakage totals calculated under subsection (3) of this section shall
include annual figures and the approved alternative
methodology's numerical standard(s); and
(iii) For systems not fully metered, the status of meter
installation and any actions taken to minimize leakage.
(b) Municipal water suppliers will be considered in
compliance with this section if any of the following
conditions are satisfied:
(i) Distribution system leakage calculated in accordance
with subsection (2) of this section is ten percent or less for
the last three-year average;
(ii) Distribution system leakage calculated under subsection (3) of this section meets
the numerical standards for the approved
alternative methodology for the last three-year average;
(iii) For systems serving less than five hundred total
connections, distribution system leakage calculated in
accordance with subsection (2) of this section is twenty percent or less for the last three-year average
and the steps outlined in subsection (5) of this section are
completed; or
(iv) A water loss control action plan has been developed
and implemented under subsection (4) of
this section and the system is meeting the implementation
schedule.
(2) Calculate the percent of distribution system leakage
annually using the following equation:
DSL = [(TP - AC)/(TP)] x 100
Where:
DSL
=
Percent of Distribution System
Leakage (%)
TP
=
Total Water Produced and Purchased
AC
=
Authorized Consumption
(a) Total water produced and purchased, and authorized
consumption must be calculated using data from meters
installed under WAC 246-290-496. Elements of authorized
consumption that cannot be metered, such as fire flow, must be
estimated.
(b) All or portions of transmission lines may be excluded
when determining distribution system leakage.
(c) Any water that cannot be accounted for shall be
considered distribution system leakage.
(3) Municipal water suppliers may use an alternative
methodology to calculate distribution system leakage if both
(a) and (b) of this subsection are satisfied.
(a) The alternative methodology is contained in published
standards or specifications of the department, Environmental
Protection Agency, American Water Works Association, American
Public Works Association, or American Society of Civil
Engineers.
(b) The alternative methodology is approved for statewide
use by the department, to provide a better evaluation of
distribution system leakage than percent of total water
produced and purchased, is appropriate for the system
requesting to use it, and uses numerical standards so that
compliance and action levels can be determined.
(4) If the average distribution system leakage for the
last three years does not meet the standard calculated under subsection (1)(b)(i), (ii), or (iii)
of this section, the municipal water supplier shall develop
and implement a water loss control action plan. Municipal
water suppliers shall submit the water loss control action
plan to the department as part of a water use efficiency
program under WAC 246-290-810 and upon request by the
department. The control methods described in a water loss
control action plan shall be commensurate with the level of
leakage reported. The following items shall be included in
the water loss control action plan:
(a) The control methods necessary to achieve compliance
with the distribution system leakage standard;
(b) An implementation schedule;
(c) A budget that demonstrates how the control methods
will be funded;
(d) Any technical or economic concerns which may affect
the system's ability to implement a program or comply with the
standard including past efforts and investments to minimize
leakage;
(e) If the average distribution system leakage calculated
under subsection (2) of this section is greater than ten and
less than twenty percent of total water produced
and purchased, the water loss control action plan must assess
data accuracy and data collection;
(f) If the average distribution system leakage calculated
under subsection (2) of this section is between twenty and
twenty-nine percent of total water produced and purchased, the
water loss control action plan must include elements listed
under (e) of this subsection and implementation of field
activities such as actively repairing leaks or maintaining
meters within twelve months of determining standard
exceedance;
(g) If the average distribution system leakage calculated
under subsection (2) of this section is at thirty percent or
above the total water produced and purchased, the water loss
control action plan must include elements listed under (e) and
(f) of this subsection and include implementation of
additional control methods to reduce leakage within six months
of determining standard exceedance; and
(h) If the average distribution system leakage calculated
under subsection (3) of this section is over the approved
alternative methodology's numerical standard, the department
will take appropriate compliance actions and work
collaboratively with the municipal water supplier to ensure
the control methods and level of activity are commensurate
with the level of leakage.
(5) Systems serving less than five hundred total
connections may submit a request to the department for
approval of an average distribution system leakage up to
twenty percent. The following information must be submitted
to the department with the request:
(a) Production volume;
(b) Distribution system leakage volume;
(c) Evidence documenting that:
(i) A leak detection survey using best available
technologies has been completed on the system within the past
six years;
(ii) All leaks found have been repaired;
(iii) The system is unable to locate additional leaks;
and
(iv) Ongoing efforts to minimize leakage are included as
part of the system's water use efficiency program; and
(d) Any technical concerns or economic concerns, or other
system characteristics justifying the higher distribution
system leakage.