Document ID: EPA-HQ-OW-2008-0517-0366
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-12-28T05:00Z

SEQ CHAPTER \h \r 1 MEMORANDUM

TO:	Tom Born, Ore Mining and Dressing Point Source Category Review Lead

Carey Johnston, Work Assignment Manager	(WAM)

	

FROM:	Chris Krejci, ERG

		Eleanor Codding, ERG									

DATE:	04 December 2008

SUBJECT:	Past Comments Received by EPA on Ore Mining ELGs and Summary of
2008 MSGP

This memorandum summarizes ERG’s progress to-date on the preliminary
study of the Ore Mining and Dressing Point Source Category (Part 440).
ERG is supporting EPA’s annual review of existing effluent limitations
guidelines and standards (ELGs) and identification of possible new ELGs.
As part of the annual review, EPA is conducting a preliminary study of
the Ore Mining and Dressing Point Source Category to determine whether a
detailed study is warranted. 

This memorandum presents findings on three main tasks that ERG began for
the Preliminary Study of the Ore Mining and Dressing Point Source
Category:

Part I – Identified past comments received by EPA on the ELGs for the
Ore Mining and Dressing Point Source Category;

Part II – Reviewed the 2008 Federal Multi-Sector General Permit (MSGP)
and summarized information relevant to the Ore Mining and Dressing Point
Source Category; and

Part III – Identified differences relevant to the Ore Mining and
Dressing Point Source Category between the Federal MSGPs published in
2000 and 2008. 

The following sections describe these tasks in detail. Attachments A and
B at the end of this memo include a 304(m) Issue/Industry Nomination
Form for the Ore Mining and Dressing Point Source Category and a
detailed outline of relevant sections from the 2008 MSGP, respectively.
PART I. PAST COMMENTS ON THE ORE MINING AND DRESSING ELGs

EPA has previously received the following comments from stakeholders and
EPA regional staff regarding the ELGs for the Ore Mining and Dressing
Point Source Category documented in the 2004 Technical Support Document
(TSD) for the 2004 ELG Program Plan (U.S. EPA, 2004):

The current ELGs may be outdated and the BAT technology basis may no
longer be appropriate;

The recommendations of EPA’s National Mining Team, which include water
budgets and closure plans, should be considered when revising the hard
rock mining ELGs;

The decision to exclude seepage from overburden piles and waste dumps
from the 40 CFR Part 440 definition of mine drainage should be reversed;
and

Discharges from the Ore Mining and Dressing Industry are a source of
significant water quality impacts in the regions where they are
prevalent.

The remainder of this section elaborates on these comments and
identifies the sources where possible.

The current ELGs may be outdated and the BAT technology basis may no
longer be appropriate.

John Hillenbrand and John Tinger from EPA Region 9 submitted a 304(m)
Issue/Industry Nomination Form for the Ore Mining and Dressing Category
(See Attachment A), suggesting the following two examples of BAT for
consideration:

Reclamation of waste rock or overburden and tailing piles by regrading
to natural contours and re-vegetating; and

Containment of stormwater through grading, berms, and/or ponds.

According to the commenters, the suggested measures for BAT would be
relatively simple and mainly require the moving of soil – which mines
already do on a regular basis. The commenters also submitted a list of
mines that already employ the suggested measures for BAT (U.S. EPA,
2003a).

The recommendations of EPA’s National Mining Team, which include water
budgets and closure plans, should be considered when revising the hard
rock mining ELGs.

This comment was cited in the 2004 TSD, but ERG does not have additional
information on the comment.

The decision to exclude seepage from overburden piles and waste dumps
from the 40 CFR Part 440 definition of mine drainage should be reversed.

Two commenters requested the renewed inclusion of certain mine
discharges in the wastes regulated by Part 440: Clean Water Network and
Region 9 staff.

In their 304(m) Issue/Industry Nomination Form, Region 9 staff stated
that (See Attachment A):

Approximately 100 active hard rock mine sites exist in mostly the
Western States and Alaska – many sites are covered only by a
stormwater permit;

Preliminary data from the MSGP indicate high concentrations of metals in
both active and inactive mine site runoff;

Discharge volumes are significant due to the large area of many hard
rock mining sites;

Most states are not addressing mine site runoff; and

The requirements of the MSGP are not sufficient to control wastewater
(U.S. EPA, 2003a).

Members of the Clean Water Network submitted the following comment on
the Effluent Guidelines Program Plan for 2002/2003 (also submitted
earlier in 1998):

In 1998 Clean Water Network members with the Western Action Mining
Project and

Earthjustice Legal Defense Fund submitted comments to EPA with regards
to EPA’s decision to substantially reduce the applicability of Part
440 ELGs to discharges from waste rock piles, overburden piles and other
sources of water pollution. EPA has not responded to that request. Today
we request again that EPA again include seepage from waste dumps in its
Part 440 ELG definition of “mine drainage”. EPA has the data and
resources to regulate seepage from waste dumps.

Discharges from the Ore Mining and Dressing Industry are a source of
significant water quality impacts in the regions where they are
prevalent.

This comment was cited in the 2004 TSD, but ERG does not have additional
information on this comment. According to EPA’s memorandum entitled
Description and Results of EPA Methodology to Synthesize Screening Level
Results for the Effluent Guidelines Program Plan for 2004/2005,” this
comment was made on the proposed Effluent Guidelines Program Plan for
2002/2003. ERG searched the comment response document associated with
this plan, but was not able to locate the comment. 

PART II. REVIEW OF THE 2008 MSGP

The 2008 MSGP regulates discharges of stormwater from industrial
activities in 29 different industrial sectors. Facilities are permitted
by the 2008 MSGP in five states (Massachusetts, New Hampshire, New
Mexico, Alaska, and Idaho), on certain Native American reservations, and
at federal facilities located in EPA Regions 1, 2, 3, 5, 6, 9, and 10.
Although the five states that are covered by the 2008 MSGP did not have
state general permit programs at the time of the MSGP’s publication,
Alaska will be transitioning federally administered permits (including
stormwater permits) into their state program as they receive NPDES
program primacy over the next few years (Alaska Department of
Environmental Conservation, 2008). The MSGP is issued by EPA regions,
and not all EPA regions issued the new permit. All states in those
regions that did not issue the 2008 MSGP (Regions 4, 7, and 8) have
NPDES primacy and an approved state general permit program.  

The 2008 MSGP requires benchmark monitoring, Stormwater Pollution
Prevention Plans (SWPPPs), regular site inspections, and narrative
effluent limits. For a detailed outline of the sections of the 2008 MSGP
applicable to ore mining facilities, see Attachment B at the end of this
memo.

Applicability

In general, the MSGP covers stormwater discharges from both active and
inactive facilities in the Ore Mining and Dressing Point Source
Category. The MSGP specifically covers discharges from waste rock and
overburden piles; stormwater discharges from a variety of other
industrial areas (e.g., roads, parking lots, buildings) supporting ore
mining and dressing operations are also covered. 

The MSGP does not cover any of the discharges regulated by the Ore
Mining and Dressing ELGs at 40 CFR Part 440. The MSGP also specifically
excludes drainage from adits, as well as discharges from contaminated
springs or seeps in waste rock dumps that do not specifically result
from precipitation events. 

Effluent Limits 

The 2008 MSGP sets requirements for technology-based and water
quality-based effluent limits. Water quality-based limits are not
specified in the permit document, but the MSGP refers to local water
quality-based standards imposed by TMDL studies or local (state/tribal)
regulatory agencies.   

Narrative technology-based limits are set in the MSGP for clearing,
grading, and excavation activities. The narrative limits specified in
the MSGP consist of management practices and inspection protocols. The
MSGP lists the following management practices:

General control measures;

Good housekeeping practices (e.g., litter containment, spill
prevention); and

Detention/retention structures.

In addition to these measures, the permittee is required to inspect the
site once every seven days or once every month if the site is
stabilized, frozen, or going through a dry season in arid/semi-arid
areas. Site inspections are required for the following areas:

All areas disturbed by clearing, grading, and excavation and areas used
for storage of materials exposed to precipitation;

Erosion and sedimentation (E&S) controls;

Discharge locations; and

Vehicle Entry/Exit Locations.

Benchmark Monitoring Requirements

Active facilities covered by the MSGP must monitor discharges from waste
rock and overburden piles for the parameters in Tables 1 and 2, as well
as the ore-specific parameters in Table 3. The parameters in Tables 1
and 2 are compared to the listed benchmark concentration to determine
whether corrective actions (i.e. additional control measures) are
needed.

Table 1. Parameters with Independent Benchmarks

Parameter	Benchmark Monitoring Cutoff Concentration

Total Suspended Solids (TSS)	100 mg/L

Turbidity	50 NTU

pH	6.0 – 9.0 Standard Units

Hardness	No Benchmark

Total Antimony 	0.64 mg/L 

Total Arsenic 	0.15 mg/ L 

Total Beryllium 	0.13 mg/L 

Total Iron 	1.0 mg/L 

Total Mercury 	0.0014 mg/L 

Total Selenium 	0.005 mg/L 

Table 2. Parameters with Benchmarks Based on Water Hardness

Parameter	Water Hardness Range (mg/L)

	<25	25-50 	50-75 	75-100 	100-125 	125-150 	150-175 	175-200 	200-225 
225-250 	250+ 

Cadmium	0.0005	0.0008	0.0013	0.0018	0.0023	0.0029	0.0034	0.0039	0.0045
0.005	0.0053

Copper	0.0038	0.0056	0.009	0.0123	0.0156	0.0189	0.0221	0.0253	0.0285
0.0316	0.0332

Lead	0.014	0.023	0.045	0.069	0.095	0.122	0.151	0.182	0.213	0.246	0.262

Nickel	0.15	0.2	0.32	0.42	0.52	0.61	0.71	0.8	0.89	0.98	1.02

Silver	0.0007	0.0007	0.0017	0.003	0.0046	0.0065	0.0087	0.0112	0.0138
0.0168	0.0183

Zinc	0.04	0.05	0.08	0.11	0.13	0.16	0.18	0.2	0.23	0.25	0.26

Table 3. Parameters Specific to the Type of Ore Being Mined

Type of Ore Mined	TSS	pH	Arsenic	Cadmium (H)	COD	Copper (H)	Iron	Lead
(H)	Mercury	Nickel (H)	Radium*	Uranium	Zinc (H)

Tungsten	X 	X 	X 	X 

X 

X 

	X 

Nickel	X 	X 	X 	X 

X 

X 

	X 

Aluminum	X 	X 	 

X 

Mercury	X 	X 	 

	X 

	Iron	X 	X 	 

**

Platinum 	 	 	 	X 

X 

X 

	X 

Titanium 	X 	X 	 

X 

	X 

	X 

Vanadium 	X 	X 	X 	X 

X 

X 

	X 

Molybdenum 	X 	X 	X 	X 

X 

X 	X 

X 

Uranium, Radium, and Vanadium	X 	X 	X 

X 

X 	X 	X 

Copper 	X

X

All metals are total metals unless otherwise specified.

*Total and dissolved radium

**Dissolved Iron

(H) – Permittee is required to measure hardness along with the metal
of concern.

Benchmark monitoring is required in the first year of activity under the
MSGP. If the average of the first four quarterly monitoring results is
below the specified benchmark for all parameters, the permittee is no
longer required to monitor for the term of the permit. If any of the
benchmark values are exceeded, the permittee must either modify the BMPs
employed at the site or show just cause for an exception. Exceptions are
granted in the following two cases:

The permittee shows that further pollutant reduction is not economically
feasible considering best industry practices; or

Pollutant levels contributing to exceedances of specified benchmark
values are attributable to background levels.

In either case, the permittee will provide documentation to EPA that
must also be included in the site-specific SWPPP.

SWPPP Requirements

Under the 2008 MSGP, the permittee is required to maintain an updated,
site-specific SWPPP containing the following:

A general description of the nature of the operations occurring at the
site;

A site map with relevant drainage boundaries possible pollutant sources
analogous to a conceptual model; and

An analysis of the type of pollutants that have reasonable potential to
be found in stormwater discharged from the site. 

In addition to these requirements, the SWPPP functions generally as a
total disclosure document for all findings and analyses related to
stormwater impacts from the site. 

PART III. CHANGES IN THE 2008 MSGP

Table 4 summarizes changes between the 2000 and 2008 MSGP. The most
significant additions to the 2008 MSGP are

More frequent benchmark monitoring requirements;

More stringent benchmark concentrations for arsenic, mercury, and
selenium; 

More frequent site inspections; and

Clarifying text to determine when corrective actions are needed.

Table 4. Changes to the 2008 MSGP Affecting the Ore Mining and Dressing
Industry

Permit Section	Description of Change

Effluent Limits 

	Clearing, grading, and excavation activities disturbing greater than
one acre were not covered under the 2000 MSGP and had to be covered
under the General Construction Permit (these activities have been
incorporated into the 2008 permit).

	2008 MSGP incorporated management practices including good housekeeping
measures as well as detention/retention structures.

Site Inspections	Changed inspection frequency for active sites from
monthly to once every seven days or once every fourteen days and within
24 hours of a storm event 0.5 inches or greater. 

Monitoring Requirements

	Changed benchmark monitoring from two years to one. If facility exceeds
benchmark in first year, facility has to continue benchmark monitoring
for a second year – old permit allowed facility to wait one year
before resuming benchmark monitoring.

	Clarifies that facilities that exceed the benchmark values will either
need to modify BMPs or claim an exception due to background
contamination or lack of economic feasibility.

	Changed turbidity benchmark from 5 NTUs above background to 50 NTUs
total.

	Changed arsenic benchmark from 0.16854 to 0.15 mg/L.

	Changed selenium benchmark from 0.2385 to 0.005 mg/L.

	Changed mercury benchmark from 0.0024 to 0.0014 mg/L.

	Removed manganese monitoring requirement and benchmark.

	Clarified and revised the hardness-based parameter limits.

	DMRs must be submitted postmarked no later than January 28 in the 2000
MSGP. Omitted that because DMRs are submitted continuously.

	Added monitoring requirement for facilities discharging to impaired
water bodies.

	Removed general requirement for coal pile monitoring.

	Includes a waiver for benchmark monitoring at inactive and un-staffed
sites.

Reporting and Recordkeeping	Requires submittal of an annual report
including results from the comprehensive site inspections and any
corrective action documentation.

Termination of Permit Coverage	Added a section discussing termination of
permit coverage for reclaimed sites.

REFERENCES

Alaska Department of Environmental Conservation, 2008. NPDES Program
Webpage. Available online at:
http://dec.state.ak.us/water/npdes/index.htm.

Date accessed: 03 December, 2008.

U.S. EPA, 1997. National Hardrock Mining Framework. Washington, DC
(September).

Available online at: http://cfpub.epa.gov/npdes/indpermitting/mining.cfm

Date accessed: 21 November, 2008.

U.S. EPA, 2003a. Gathering EPA Experts’ Inputs for the Effluent
Guidelines Program Plan for 2004/2005. Washington, DC (December).

U.S. EPA, 2002. Responses to Comments Received on Proposed Effluent
Guidelines Program Plan for 2002/2003. Washington, DC (June).

U.S. EPA, 2003b. Description and Results of EPA Methodology to
Synthesize Screening Level Results for the Effluent Guidelines Program
Plan for 2004/2005. Washington, DC (December).

 

U.S. EPA, 2004. Technical Support Document for the 2004 Effluent
Guidelines Program Plan. EPA-821-R-04-014. Washington, DC (December).

U.S. EPA, 2008. Multi-Sector General Permit For Stormwater Discharges
Associated With Industrial Activity (MSGP). Washington, DC (September).

Available online at: http://cfpub.epa.gov/npdes/stormwater/msgp.cfm

Date accessed: 21 November, 2008. Attachment A

304(M) ISSUE/INDUSTRY NOMINATION FORM FOR ORE MINING AND
DRESSINGAttachment B

DETAILED OUTLINE OF SECTIONS FROM THE 2008 MSGP APPLICABLE TO ORE MINING
AND DRESSING FACILITIESApplicability

Mines abandoned on federal lands

Stormwater that has come in contact with one of the following:

Overburden

Raw material

Intermediate/Finished Product

Byproduct

Waste Product

Covers all stormwater from the following:

Inactive facilities

Exploration and construction facilities

Facilities undergoing reclamation

Covers stormwater from the following areas of active and temporarily
inactive facilities:

Waste rock piles

Overburden piles6

Topsoil piles

Offsite haul/access roads

Onsite haul/access roads constructed of waste rock/overburden/spent ore7

Onsite haul/access roads not constructed of waste rock/overburden/spent
ore except if mine drainage is used for dust control

Runoff from tailings dams or dikes when not constructed of waste rock or
tailings and no process fluids present6

Concentration building if no contact with material piles

Administrative buildings or housing if mixed with stormwater from
industrial area

Storage areas for chemicals, explosives, and fuel

Docking facility 

Vehicle/equipment maintenance areas

Parking areas and buildings

Power plant

Truck wash area7

Unclaimed, disturbed areas outside of mined area

Reclamation areas released from reclamation prior to December 17, 1990

Partially/inadequately reclaimed areas not released from reclamation

Does not cover the following:

Discharges regulated under 40 CFR Part 440

Adit drainage

Contaminated springs or seeps discharging from waste rock dumps not
directly resulting from precipitation events

Monitoring and Reporting Requirements for all Ore Mining Facilities –
Active facilities must monitor discharges from waste rock and overburden
piles for the parameters in Tables 1 and 2 of the memo, as well as the
ore-specific parameters in Table 3 of the memo. Benchmark monitoring
should be done quarterly in the first year of activity and in subsequent
years for all parameters which continue to exceed the respective
benchmark value. There are no monitoring requirements for inactive and
un-staffed sites.

Technology-Based Effluent Limits for Clearing, Grading, and Excavation
Activities

Management practices

Selecting and installing control measures – for all affected areas,
permittee must implement measures that meet applicable Part 2 Effluent
limits

Good housekeeping – prevent litter, debris, and chemicals from
becoming stormwater pollution sources  

Runoff detention/retention – 

For locations draining more than one acre, sediment basins and/or
temporary sediment traps should be used. 

At a minimum silt fences, vegetative buffer strips, or equivalent
sediment controls are required for all down-slope boundaries

Permittee must remove sediment from sediment basins/traps when capacity
has been reduced by 50 percent 

Inspection

Frequency – Once every seven days or once every month if site is
stabilized, frozen, or going through dry season in arid/semi-arid area

The following locations must be inspected:

All areas disturbed by clearing, grading, and excavation and areas used
for storage of materials exposed to precipitation;

Erosion and sedimentation (E&S) controls – must be observed to ensure
proper operation;

Discharge locations – must be observed to ascertain whether E&S
controls are preventing significant impacts to waters of the U.S; and

Vehicle Entry/Exit Locations – must be inspected for evidence of
significant off-site sediment tracking.

Requirements for cessation

Inspection and maintenance – All control measures (including BMPs)
must be inspected and maintained until final stabilization has been
achieved for all disturbed areas or until mining has commenced on
temporarily stabilized areas.

Final and Temporary stabilization of disturbed areas – Stabilization
measures should be initiated no more than 14 days after clearing,
grading, and/or excavation activities cease. Until temporary/final
stabilization is achieved, interim measures (i.e. erosion control
blanket with seed base and tackifiers) should be employed.

Additional Technology-Based Effluent Limits.

Employee training – conduct annual training at active and temporarily
inactive sites.

Stormwater controls – potential pollutants identified in Part 8.G.6.3
shall determine the appropriateness of the control measures selected. 

Diversion options

Interceptors (e.g., dikes, swales, curbs, berms)

Pipe slope drains

Subsurface drains

Conveyance systems (e.g., channels, gutters, culverts)

Capping – where needed, identify the source that requires capping and
the capping material to be used

Treatment – where needed, identify the type/location.

Certification of discharge testing – evaluate all outfalls for the
presence of mining-related, non-stormwater discharges (e.g., mine
drainage, process water). 

Additional SWPPP Requirements

Nature of Industrial Activities 

Document mining activities that could affect stormwater discharges

Include site location description relative to transportation routes and
communities

Site Map – should include locations of the following:

Mine and mill site boundaries

Access and haul roads

Drainage areas of outfalls with indications of types of discharges from
the drainage areas

Permitted discharges covered under individual NPDES permit

Outdoor equipment storage, fueling, and maintenance areas

Materials handling areas

Outdoor manufacturing, storage, and disposal areas

Overburden, materials, soils, and waste storage areas

Mine drainage and process water locations

Tailings piles and ponds (proposed and existing)

Heap leach pads

Off-site discharge points for mine drainage/process water

Surface waters

Boundaries of tributary areas subject to ELGs

Reclaimed areas 

Potential Pollutant Sources – for each area where industrial
stormwater discharges will occur, permittee will include the following:

Types of pollutants (e.g., heavy metals, sediment) likely present in
significant amounts considering the following:

Mineralogy of ore and waste rock

Toxicity and quantity of chemicals used, produced or discharged

Likelihood of contact with stormwater

Vegetation (if any)

History of leaks/spills

Summary of existing ore, waste rock, or overburden characterization data
and test results for acid generation potential (updated with new
information) 

Documentation of Control Measures – document measures consistent with
7.G.5.2.

Employee training – include documentation of employee training in
SWPPP.

Certification of Permit Coverage for Commingled Non-Stormwater
Discharges – Include certification in SWPPP that identifies any
non-stormwater discharges and the permit, limits, and compliance points
that regulate them.

Additional Inspection Requirements – sites that are not subject to
clearing, grading, and/or excavating should be inspected quarterly

Termination of Permit Coverage

For sites reclaimed after December 17, 1990 – no longer required to
maintain coverage under permit, unless the reclaimed site was not
subject to reclamation requirements, in which case it must be reclaimed.

For sites reclaimed before December 17, 1990 – no longer required to
maintain coverage under this permit if site(s) have been reclaimed.

Monitoring

Substantially Identical Outfalls – If facility has two or more
outfalls that discharge identical effluents, permittee may identify them
and include justification in the SWPPP, and report monitoring results
from one outfall for all other substantially identical outfalls.

Commingled discharges – If stormwater discharges are commingled with
discharges not regulated by MSGP, than permittee must sample regulated
discharges prior to mixing (to the extent practical).

Measurable Storm Event – Monitoring must be performed at least 72
hours after a storm event that results in a discharge.

Sample Type – At least one grab sample must be taken with 30 minutes
of storm event.

Adverse Weather Conditions – when adverse weather conditions prevent
sample collection according to schedule, permittee must take a
substitute sample during the next qualified storm event. Permittee must
still file a benchmark monitoring report indicating the basis for not
sampling during the usual period.

Climates with Irregular Stormwater Runoff – In arid/semi-arid climates
where runoff does not occur for extended periods, sampling events may be
distributed during seasons when discharge occurs.

Benchmark monitoring

Inactive and Un-staffed sites – sites that are inactive and un-staffed
are not required to perform benchmark monitoring.

Schedule - Must be conducted quarterly.

Benchmark exceedances – If average of first four quarters exceeds
benchmark, permittee must evaluate existing BMPs and do one of the
following:

Make modification and sample four more quarters showing that average has
dropped below benchmark; or

Determine that no further reduction is feasible in light of best
industry practices and provide justification and documentation to EPA
(include in SWPPP)

Natural Background Pollutant Levels – permittee may claim that
benchmark exceedances are due to natural background levels if monitoring
data are less than or equal to background levels. Permittee must provide
justification for claim and notify EPA.

 Region 4 includes AL, FL, GA, KY, MS, NC, SC, and TN. Region 7 includes
IA, KS, MO, and NE. Region 8 includes CO, MT, ND, SD, UT, and WY.

 The MSGP does not cover the following mine sites: (1) sites with their
stormwater discharges regulated by an individual permit; and (2) sites
without any discharge of stormwater. A facility has the option of
obtaining an individual permit for stormwater discharges instead of
requesting coverage under the MSGP; however, in practice this is seldom
done. Almost all mine sites discharge stormwater (e.g., from haul roads,
process areas, equipment storage areas, mine waste rock).

 Table G-4 of the MSGP lists what wastewaters from mining activities are
covered by Part 440 and what wastewaters are to be covered by the
industrial MSGP. In response to litigation from the National Mining
Association, EPA revised its interpretation of applicability for
wastewaters from hard rock mining operations. Under the revised
interpretation, runoff from waste rock and overburden piles is not
subject to effluent guidelines unless it naturally drains (or is
intentionally diverted) to a point source and combines with “mine
drainage” that is otherwise subject to the effluent guidelines (65 FR
64774, October 30, 2000).

 Or once every fourteen days and within 24 hours of a storm event of 0.5
inches or greater. 

 Where discharge locations are inaccessible, nearby downstream locations
must be inspected to the extent that inspection is practical.

 If composed entirely of stormwater and not combining with mine drainage
(see also footnote 2)

 If no excessive contact with waste product that would otherwise
constitute mine drainage (see also footnote 2)

 Part 2 includes both technology-based and water quality-based effluent
limits. The technology-based effluent limits are non-numeric and include
general management practices such as minimizing exposure of
manufacturing and processing areas to stormwater, good housekeeping,
maintenance of industrial equipment, spill prevention and response, E&S
controls, and general runoff management.  The water-quality based limits
simply require the permittee to meet any local water quality standards
and to comply with TMDLs for any impaired water bodies.

 Unless a sediment basin providing storage for a 2-year, 24 hour storm
event or 3,600 cubic feet per drained acre is provided.

 Or once every fourteen days and within 24 hours of a storm event of 0.5
inches or greater 

 Where discharge locations are inaccessible, nearby downstream locations
must be inspected to the extent that inspection is practical

 In areas where vegetative stabilization is not possible within fourteen
days after activities have ceased, measures should be initiated as soon
as possible. 

 Sites which discharge to impaired/outstanding waters for sediment or
nitrogen must be inspected monthly.

 Except in the condition of snowmelt or where site-specific criteria
prove that a sample taken less than 72 hours afterward will be
representative. 

 If it is not possible to take a sample within 30 minutes, the sample
must be taken as soon as possible, and justification for the delay must
be made in the SWPPP.

 If data still exceed benchmark after modification, permittee must again
determine whether to modify BMPs or to determine that further reductions
are not feasible.

 Background pollutants must be naturally occurring and cannot be
pollutants from former activities at other sites or run-on from
off-site. 

Memorandum

04 December 2008

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Memorandum

04 December 2008

  PAGE  1 

B-  PAGE  5