Summary of Variance Examplesfor RWG

Variance "Type": Individual variances issued to three municipal sewage treatment plants

40 CFR § 131.10(g)(6) - Controls more stringent than those required by sections 301(b) and 306 of the Act would result in substantial and widespread economic and social impact

Maintain current discharge levels during the term of the variance while working towards implementation of measures which will reduce metal concentrations over time. Specific requirements related to inflow and infiltration work and investigating treatment options included in the NPDES permits.

2001	Original exchanges between facilities and EPA pertaining to the need for and economic analysis conducted to support issuance of a variance.
August 2002-January 2003	EPA issues public notice for the variances and the draft permits incorporating the variances.
August 1, 2004	EPA incorporates variances into NPDES permits for the three facilities with a variance effective date of August 1, 2004, and expiration date of August 1, 2009.

January 30, 2009/ February 19, 2009	Idaho DEQ receives requests for variance renewals from the three facilities originally granted variances.
April 1, 2009	Idaho DEQ publishes a notice of the public comment period and public hearing on its tentative determination to grant variances for these three facilities (i.e., variance renewals).
April 22, 2009	Idaho DEQ holds a public hearing on its tentative determination.
May 1, 2009	Public comment period closes.
June 12, 2009	EPA receives Idaho DEQ's WQS submission for the three variance renewals.
July 22, 2009	EPA approves the variance renewals.

Variance "Type": multiple discharger variance (MDV) (may include either municipal or industrial permits)

40 CFR § 131.10(g)(6) - Controls more stringent than those required by sections 301(b) and 306 of the Act would result in substantial and widespread economic and social impact

For reissuance of permits with reasonable potential and existing mercury limits:

• The mercury permit limit will be set at the facility-specific LCA (using MI’s mercury LCA calculation procedures) for the life of the permit.

• Require a mercury pollutant minimization plan for the duration of the permit so that reasonable progress is made toward attaining the water quality standard.

• Use of a LCA that is calculated using some procedure other than MI’s mercury LCA calculation procedures will be evaluated by MDEQ on a case-by-case basis and submitted to EPA for review and approval.

For reissuance of permits with reasonable potential but without previous mercury limits:

• Set the mercury permit limit at the facility-specific LCA (using MI’s mercury LCA calculation procedures) effective at Year 3 (allow 2 years of monitoring before the limit takes effect).

• Require a mercury pollutant minimization plan for the duration of the permit so that reasonable progress is made toward attaining the WQS.

For reissuance of permits with insufficient data for mercury limit determination:

• Require monthly monitoring with Method 1631 to start at permit issuance and continue for the permit duration.

• Include a Special Condition that triggers a mercury pollutant minimization plan if the monitoring data after one year indicates the presence of mercury at levels indicating reasonable potential to cause or contribute to exceedances of water quality standards.

• Evaluate the need for a permit modification to include a mercury limit, or include a mercury limit at the time of permit reissuance, if reasonable potential exists.

February 18, 2000	Michigan DEQ submitted its Mercury Permitting Strategy, which incorporated a MDV for mercury, to EPA. The Strategy (applicable from 2000-2004) incorporated an interim level currently achievable (LCA) of 30 ng/L.
May 24, 2002	EPA approves MDV.

May 18, 2004	Michigan DEQ submitted its revised Mercury Permitting Strategy, which incorporated a MDV for mercury, to EPA. The revised Strategy (applicable from 2005-2009) incorporated an interim LCA of 10 ng/L.
June 29, 2004	EPA approves the MDV.
2004-2007	EPA’s approval of the variance, particularly the uniform LCA of 10 ng/L, was challenged in federal court.
November 30, 2007	A settlement agreement in regards to the above-noted challenge was reached.
September 5, 2008	Michigan DEQ submits a revised procedure for calculating LCAs to EPA which replaced a component of the previously approved mercury MDV that established a statewide LCA of 10 ng/L.
September 30, 2008	EPA approves the methodology submitted to EPA on September 5, 2008, that Michigan will use to develop LCAs.