REP21401

• Permit No: C1981025
• IBM Index Class Name: Report
• Doc Name: PASSIVE MINE DRAINAGE TREATMENT
• Media Type: D
• Archive: No

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Mine near Carbonde le, Colorado.
Coe[ data for Chas ty stems ere presented in
terms of design, construction, end maintenance.
A method for financing ongoing maintenance Coate
is suRgett ed. The purpose o[ this presentation
is to provide • preliminary basis for cost
benefit comps rirons betreen Paa eive Mine
Drainage Treatment gyatemr and other acid mine
drainage treatment approache e.
PMDT gv stem Descriptions
Hershall No. S PMDT av stem - The Marshall I 5
coal mine is located 1 2 mile couch of [he torn
of Marshall end 4 miles south of Boulder,
Colorado. This mine ras operated by the
Ha rshalt Coal Comoanv intermit [enl lv from 19J9
to 1967. I[ it one of relatively (er inactive
coal mines in Colorado rfi ich discharge acid mine
racer. The rater drains oNc ac rose a portion of
[he Boulder City Open Spate land. The mint dis-
charges 17 [0 75 gallons pet minute of rater
containing elevated coot ant cations of iron, aun-
ganere, :inc, cadmiw, and gulf ate at • DN of
L.B. This nine effluent drains into Bouth
Boulder Creek, • high quality tributary of the
South Platte River.
The Marshall • S PMDT ryt[em vas tonstrutted [o
feet the feasibility of passive mine dreinege
treatment. Construction rel completed in July,
1984. The eyes em inc orpontea three .bu it
f ¢il ieiee: an artificial peat bog; • limestone
filled dreinege channel; and save ral vaterfal L.
The artif ie iel pee[ bog server a an organ it ion
exchange end filter e,ediw for [he removal of
heavy metals from mine dreinege. The bob ras
created by excavating r SS foot long and ZS foot
vide trench, 45 inches deep and filling it rich
approxima to ly 35 Cubic yards of tmmee rc ial ly
rvailable sphagnum end hypnum peat sou.
llniform exfil[racion of mine refer into the bog
rar achieved rich • rater leveling bex above ^
broad grerted re ir. A eoerte rock liner plated
at the inlet to the bog •llwa the mine rater to
pe rc ola[e evenly ^nd prevents Channeling or
surface ilort. The peat is held in place by
porous filler [e brit rod drained by a ere rent
rhaped quarried rock check dam. The bore sock
check dam ^llort rater in the peat to drain
freely from the bog.
The second stage of the treatment tyrtem is
line scone filled channel approximate ly 700 feet
long. The limestone gravels are J(4" and
smeller in diameter. The limer[one se lest ed is
nearly Dure calf ium to rbon•te by rei ght. It
provides ^ source o[ alkalinity for the neu[-
ralizetion of mineral acidity.
The third component of the rys[em is • aeries of
three small drop at ruttures placed io the
thennel to provide aeration. Theta drop stru~-
tures alto provide • scans of met scaring [lore in
the sy rt em. Theta to ructuret are placed in the
thennel in naturally steep Rection^ a[ positiam
60, 200 and 220 feet be for the loots rock check
dam. Voter flaring over the rei rr drops ap-
proximately 3 feet onto limestone gravel bel or.

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Thompson No. 2 PTOT gv stem - The Thompson / 2- \
coal mine is lac aced near Ca rbonde le, Colorado
tn` tTic aniij of [_he Bnoriun Coal Company
YhIIiLpion Z`iee~_ Coil Mineq. This mine we
opeia[ed until 1966 by the Amdmt: as our-
pan __ e-h-ive_ tieen no .active ape i~[ions ac
'this mine sance~ Chet Cime. The Thompson -I 2 ~
~coal~ mine disc ages 11- 45 gallons per minute
o[ highly toxic acid mine drainage rich aig-
nificancly higher heavy metal content rations
Chan [he discharge from Che Marshall I 5 coal
mine. For example the Thompson 11 Mine effluent ~
cants ins 290 mg/1 iron, I8 mg/1 manganese, 1
mg/1 copper, and 16 mg/1 riot /~
The Thompson / 2 PMDT sy ¢em vas con ec ru<ced'
during the early rioter moot he of 1985. This
sv1[em inrorporatea the came basic facilities as
[he Marshall I 5 PMDT. The Thompson •2 PMDT
system includes a bog (tomeuhet larger than the
Marshall bog) and • steep line stone filled
channel belor the ye at bog. There is oniv one
drop structure at the Thompson PMDT system end
i[ i^ located inured iately belor the bog. The
mine rater exfiltretion devices vhich brinq
rater into the bog and alloy va[er to discharge
from the bog are aomerhet different in each
ty et em. The Thompson system emplavs • mine
rater collection end distribution system con-
sisting of • V-notch re it fol loved by a dia-
tributimn box vhich delivers mine rater to
siphon end then to a second bo: across the mine
haul road.
The Mershell treatment ry acem ras installed at
an elevation o[ 5,600 fee[ and the Thompson tre-
atment system ap<ratea a[ an elevation of 7,600
feet above sea level. The Marshall ayrtem is
designed to treat 8,500-14,400 gallons of mine
drai nags per day. The Thompson ayatem ie
designed to treat 15,000- 22,000 gpd. Also, at
noted earlier, the effluent from the Thompson 12
tool mine it of extremely poor rater quality.
Doth sy stems are considered prototypes. The
Marshall /S treatment system had higher than
antic ipeced cases during court rvct ion because it
ras a "first attempt". Numerous field revisions
of the construction plans were ne teasrry. The
Thompson f 2 system vas relatively expensive to
build since it vas designed for higher ere acme nc
tapacit ies and constructed in extremely cold
rioter veathe r.
PMDT System Design Proee+s There re re four major
arses of inve st iga[ion dur in6 [he PLOT design
proceee for the ee rvitmr: (U • race rthed ev-
alua[ion; (2) an evaluation of mining ae-
tivi[ier, (J) facilities sic ing; (4) design of
treatment fat ilitie e.
A thorough eveluetion of the rat ershede imp acted
by the mine drainages ras performed early in the
P1O7 design proceee. Ba eel ins rater quality
data rn gathered over • Buff ie ien[ period of
time [o characterise annual and seasonal fluc-
tuations in the quality of each sine drainage
^nd ice rat eiving streams. Geohydrolog is al
invettigat ions rare tarried out in order to
tharecterite flay rag imea .(ins lading rearonal