HomeMy WebLinkAboutEngineer Report 12.10.08GAMBA
& assocf ATEs
CONSULTING ENGINEERS
& LAND SURVEYORS
PHoNE: 970./945-2550
F^x: 970/945-l4lo
I Ig NINTH STREET,
sutrE 214
P,O, Box t 458
GLENwooD SPRINGS,
coLoRADo 41602-1458
Wednesdoy, December 1Oth, 2008
Jim Rodo
Environmentol Heolth Monoger
Gorfield County
I 95 West l4th Street
Rifle, Colorodo 81ó50
Originol by moil, copy by emoil io: irodo@gorfield-county'com
Re: Heron's Nest RV Pork - Remediotion steps proposol - REVISED per
communicotions with GARCO.
Deor Jim:
This is o follow-up to our previous communicotions, to updote you with
whot hqs hoppened lo dote, ond to propose some meosures to ossist in the
evoluotion of the foiled obsorption field for System #2, wiÌh on eye to
rehobilitotion os o first option, ond replocement/supplement os o foll-bock
position.
ln o previous communicotion to Mork Kodnuck, P.E. of the CDPHE, ond
copied to you, we wrote the following (in ifo/ics). We hove mode progress
on these items, os shown in bold text.
We hove o/so been working wifh Simon Cosos, owner of Heron's Nest RV Pork
on the woter seen of fhe surfoce of fhe field serving System #2. We hsve
locoted oll four inspecfion ports, ond hove observed sfonding woter in oll
four. We hove mode the following recommendofions regording the sysfem:
1 . Mow fhe gross, ond roke off the gross & mulch over the top of the
obsorpfion field serving System #2. (Nofe, fhis is fhe Sysfem #2 os it
wos numbered in the consfruction process. .which is different
from the design plons, on which if wos known os Sysfem # 7). When
fhe gross is mowed, ond the surfoce f ully visible, if will be possib/e to
evoluote if , ond how much, seff/emenf hos occu rred on fhe surfoce of
the field. Surfoce seff/emenf moY or moy not indicote sub-surfoce
seff/ement, but of the very /eosf, fhe fop surfoce of the fie/d shou/d be
re-groded fo the originoldesign intent, to shed rsinfoll ond
snowmeh. The gross hos been mowed over both fields, ond much
of the notive vegetotion hos been roked off. Low points ore evident
in severol ploces. Surfoce re-groding plons hove been developed
ond ore submitted with this letter. These plons will be implemented
on System #l immediotely, ond offer ony repoirs qre mode to
System #2.
2, Reploce ihe inspecfion riser pipes ot oll four locotions (on bofh fie/ds)
with o riser pipe which exfends opproximotely 2-feet obove fhe
finished ground surfoce. Cop with o removoble PVC cop, ond point
dork green, to help preserve fhe PVC from degrodotion by sunlight.
This willossist in f uture inspections, os fhe heovy growth of gross
Heron's Nesi RV Pork - Remediotion sleps
Wednesdoy, December I0, 2008
Poge 1 of ó
over bofh fie/ds hid the inspecfion port covers, moking inspection difficult. The
inspection ports hove been reploced with verticol riser pipes on bolh fields. We
ore recommending the instollotion of double-bend ports thot will keep roin woter
from entering the fields, while ollowing some ventilotion of the fields. A design for
these ports is ottoched.
3. Survey the bottom of the field, through the open inspecfion porfs, ot all four
corners, fo see if there hos been seff/ing of the field, ot the level of the obsorpfion
Ioyer. lf there hos been seftling, then the only solution is removol of the surfoce fill,
the chombers ond pressure piping in the oreo of fhe sett/ement, followed by
plocement of o notive soi/ or possibþ concrete sond, ond re-instollotion of the
obsorpfion system (chombers, piping, efc.) The survey hos been performed, ond
confirms thot there hos been settling in the south-west corner of the field. A
proposol to repoir this settlement is port of this remediotion plon.
4. Excovote o smo// hole, opproximotely 4-feet deep, to the west of the field, to check
the groundwoter level in the immediote vicinity of the field. Survey the wofer |evel,
ond compøre with fhe wofer leve/ observed during the design phose of this project.
(This hole hos been excovoted, but the site hos not yet been inspected, or
surveyed). The hole ond the woler level hove been surveyed, ond the informotion
indicotes thot the groundwoter level in lhe vicinity of the field hos risen since the
field wos originolly instolled. ln oddition, the south-west corner of the field hos
settled opproximotely 0.28-feel, relolive to the other three corners of the field,
which ore oll within 0.05-feet of eoch other.
5. We were told thot irrigation hos contin ued in the field of vorious fimes, ogoinsf our
odvice during the initioldesign ond construction process. We odvised the owner to
disconfinue any field irrigofion neor either of the obsorpfion fields, os if moy be
roising fhe woter level, ond contributing fo fhe problem. lrrigolion hos been
discontinued this yeor, ond will not be re-storted before next yeor, by which time
we expect to hove diversion ditches in ploce. lrrigotion up-grodient from the
obsorption fields will be discontinued.
6. Excovote o 2Joot-deep perim eter trench completely oround eoch fie/d, with o
bottom chonnel down-grodient, to direct surfoce woter owoy f rom the fields. The
perimeter frenches shou/d be 1)-feet oufside the field (in the cose of fhe eosfern
field serving Sysfem #1), ond 1?-feet oufside of the toe of slope of the mound
serving System #2. The owner hos indicoted thot he will be doing this, but the
work will not commence until ofter repoirs ond/or remediotion of the obsorption
field for System #2 is complete, including, if opplicoble, the construction of o
supplementol field. The ditch construction plon hos been modified, to ovoid on
overly-deep ditch. Current plons ore ottoched, ond show o minimum depth o{ ó-
inches, increosing os necessory to provide o minimum slope of I -percent to
doylight. A sketch showing the proposed site groding is oltoched.
7 . There is evidence of horses (horse monure, ond broken inspecfio n port lids) on fop
of both fie/ds. There is o/so evidence of possib/e vehiculor troffic over the field
serving System #1. We hove recommended fhof the owner set perimeter fencing
oround both fie/ds, preferobly outside of the perimeter trenches, to keep horses
ond vehicles off the fie/ds. The owner hos indicoted thol fences will be instolled in
occordonce with these recommendotions, but will be woiting until ofter the repoirs
Heron's Nest RV Pork - Remediotion sfeps
Wednesdoy, December 10, 2008
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ond/or remediolion of the obsorpfion field for Syslem #2 is complete, including
the supplementol field, if thot is instolled. The fence oround lhe obsorption field
for System #1 will be instolled ofter the completion of the inlerception trench ond
the site re-groding is complele.
We willbe in conf oct with Orenco Systems to evoluote how besf to deo/ with the opporent
greose in System #2. lf necessory, ond permissíble fo Orenco, we moy recommend
pumping the concrete tonk serving Sysfem #2, ond steom-c/eo ning oll three chombers of
the tsnk ond fhe recirculofion pump chomber. We willolso osk thot Orenco Sysfems send
out o represenfotive to inspect oll of the filters in both sysfems to confirm thot they ore
functioning correctly. Roger Schoffer of SCG Enterprises, in Conifer, Colorodo mode o
site visit on Mondoy November 17'h. His inspection of the odvonced lreotment systems
indicoled thot the doily flows to the obsorption field for System #l is working well. The
effluent pump records (number of pump cycles, tolol run time) indicote opproximotely
42l-gollons per doy, or 95O-gollons per doy, depending on whether the effluent
dischorge pump operotes once or twice in o given doy. ln the originol design, System
#l wos designed lo occommodote Spoces I through ó inclusive, the Office, Restrooms
qnd Loundry, Spoces 9 through 14, plus the coretokers spoce. ln foct, System #1 is
octuolly serving oll of the originolly designed spoces os obove, plus two more units
locoted neor the well site, ond hos recenfly been given six more spoces (numbers 32
through 37 inclusive), to help toke the lood off of System #2. ln the course of severol
inspections of the obsorption field for System #1, no slonding woter hos been observed
in ony of the inspection ports locoled ot the four corners of the field.
ln Roger's inspection of the records for System #2,there were extensive periods during
which lhe recorded doto for the effluent pumps indicoted thot very lorge volumes of woter
were being pumped to the obsorplion field, considerobly in excess of its design
porometers ond permitted limits. For most, if not oll of the doys reported, the totol
effluenl being pumped to the System #2 obsorpfion field exceeded, by o foctor of ot leost
two, the totol volume of potoble woter delivered by the well to the entire pork. A number
of possible explonotions exist:
I . The cycle counl, ond run-time meter for the effluent dischorge pump on System
#2 is somehow reporiing erroneous informotion.
2. The pumping rote of 5O-gollons per minute, which is the roted copocity of both
effluent pumps ot Heron's Nest, is higher thon the octuol pumping rote.
3. The existing concrete lonk hos somehow sprung o leok, ollowing significonf
groundwoter intrusion into lhe lonk, despite the tonk hoving been pumped dry
ond inspected ot the time of the initiol instollotion of the Orenco systems.
4. Some unknown source is odding thousonds of gollons of woter doily to System
#2.
5. The droin-bock through the effluent force moin from the System #2 obsorption
field is ollowing oll of the opproximotely 33O-gollons which is in the 3-inch force
moin, to re-enter the effluent pump lonk.
ó. The drqin-bock is olso ollowing effluent from the obsorplion field to come bock to
the pump tonk.
Heron's Nest RV Pork - Remediotion steps
Wednesdoy, December 10, 2008
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We mode o brief inspection of the woter system ot the pork, ond it oppeored thot the
woter meler serving the pork wos functioning correctly, recording o flow rote of
opproximotely 13 to l4-gpm. At this time, we do not believe thol there is ony error in the
reported woter use by the pork.
ln order to ovoid whot moy be on un-necessory replocement of the existing obsorpfion
field for System #2, we would like to propose on olternotive thot will ollow us fo inspect,
repoir, ond possibly cleon the surfoce of the field. ln order to inspect the field, ond repoir
the settling oreo on the south-west corner, ond possibly cleon the surfoce of the field, we
will need to hove the field pumped dry, ond both ends of the field exposed. This will
require o re-routing of the effluent from System #2 on o temporory bosis. At the
extreme, we onticipote thot this re-routing of the effluent from System #2 would be
necessory for not more thon seven doys. A proposed schedule is qttoched.
Recent woter mefer reodings, indicole thqt the totol doily flow into fhe pork do not exceed
the 1,90,|-gpd overoge doily design flow for System #1. For this reoson, we do not
believe thot the obsorption field for System #l would be overlooded with the odditionol
flow from System #2. ln order to provide on extro buffer of security, oll non-essentiol
uses of woter would be curtoiled. This would include shutting off the use of the loundry
for the entire period. Residenls would be worned in odvonce, of this shut-off. The
bqihrooms ond showers would hove to remoin ovoiloble for use by the residents, for
heolth ond sofety reosons.
We propose ihe following series of steps to help resolve the foiling field ot System #2.
l. Delivery of qt leost two truck-loods (24-cubid yords +/-) of cleon sond er94--ineh
to be used to fill in the settled ore ot the south-west corner of the
field.
2. Delivery or supply from on-site, of the fill moteriol to be ploced over the surfoce of
the fields, to help promote runoff of surfsce woter.
3. Notificoiion of the residents thot ihe loundry will be shut down for o 7-doy period
storting on o given dote. Notificotion should be given ot leost 4B-hours in
odvonce, preferobly longer.
4. Controct with o sewoge pumping compony, to hove the obsorplion field for
System #2 pumped completely dry on o given dote. Alternotely, the owner moy
eleci to ollow the field to dry noturolly, ofter the System #2 tonk hos been pumped
dty.
5. The owner hos excovotion equipment ond will stort explorotory excovotions on the
oreo of the System #2lield thot hos settled, ofterthefield hod droined or been
pumped, but ofter the Sysiem #2 concrete tonk hos been fully pumped dry.
6. Confirm the locol ovoilobility of the piping necessqry to repoir or reploce ony
piping found to be broken, or broken in the process of excovoting the field ends.
7. Confirm the locol ovoilobility of lnfiltrotor multi-port end plotes ond Quick4
chombers, in sufficient quontity to reploce oll elements ot the end of the System
#2 obsorption field. (20-multi-port end plofes, ond 20-Quick4 Chombers). This is
to ensure the obility to quickly reploce ony multi-port end cops or chombers
domoged during excovotion.
Heron's Nest RV Pqrk - Remediotion steps
Wednesdoy, December 10, 2008
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L Prepore the necessory piping modificotions to re-direct the effluent from fhe pump
chomber on Syslem #2 to the pump chomber on System #1. lnstoll piping with
boll volves to ollow the reversion to normol operotions immediotely.
9. Pump out the existing concrete septic ionk serving System #2, ond pressure wosh,
with o hot-woter wosher, the inlerior of the tonk, ond the risers, floots, ond filters.
Core sholl be token to ensure thot oll of the moteriols woshed from the tonk risers,
floot trees, ond filters is pumped out. Follow oll OSHA rules for ony person who
enters the tonk, including gos monitoring, protective clothes, protective helmet,
foce protection, supplied oir, tonk ventilotors, tripod stonds ond personnel hoisis,
etc.
lO.While the tonk is being pumped ond pressure cleoned, the obsorption field for
System #2 should olso be pumped out, which moy require pumping ot oll four of
the inspection ports, ond even opening up occess to other rows of chombers.
Alternotely, the field con be left to dry out for opproximotely 24-hours before
excovotion of the settled oreo commences.
1 'l .lnspect the interior of the tonk, ond oll components. Video the entire inside of oll
comportments of the tonk. Advise owner if ony infiltrotion, no motter how smoll, is
found. Advise if ony other repoirs or modificotions ore recommended in order to
improve operotionol functionolity. Follow oll OSHA rules for ony person who
enfers the tonk, including gos monitoring, protective clothes, protective helmet,
foce protection, supplied oir, tonk ventilotors, tripod stonds ond personnel hoists,
etc.
12.1Í ony leoks ore found, moke o determinotion os to whether the tonk con be
repoired or if it must be obondoned ond reploced. Repoirs, if necessory ond
possible, should be mode on both the interior ond exterior of the tonk wolls wilh
non-shrink grout, ond further seoled on the outside with Bituthone sheet
foundotion seolont, over the potched oreo..ì3.|f the existing tonk con be put bock into service, switch the effluent dischorge from
ihis tonk to the obsorption field serving System #1 . lÍ the tonk is determined to nol
be sound, then replocemenl tonk(s) should be ordered immediotely. Replocement
tonk(s) should hove the some or greoter copocity thon the existing.
l4.While this tonk is filling, o process which should toke opproximotely 41/z -doys (ol
the design rofe of ,l,90.l-gpd) evoluotion of the condition ond repoir/remediotion
of the obsorption field for System #2 should be conducted. Coreful trock of the
qmount of sewoge flowing into the existing concrete tonk should be loken, in ihe
form of doily depth reodings, to be used to confirm the octuol use of the system.
15.|f repoirs to the obsorption field serving System #2 connot be mode within the
obove stoted \/z-doys, coreful observotion of the condition of the obsorption field
ot Sysiem #,l, which will tempororily be serving both systems, should be kept, ond
oi the firsi sign of overlooding, the concrete tonk serving System #2 should be
pumped out ogoin.
System #2 Absorption Field Repoir/Remediotion
Assuming thot greose is evident on the obsorpiion surfoce of System #2, excovotion will continue
to expose ihe entire length of eoch end of the field. The multi-port end cops ond the pressure
tubing sholl be removed. Greose moy oppeor grey in color. The depth of the biomot in the field
Heron's Nesl RV Pqrk - Remediolion steps
Wednesdoy, December 10, 2008
Poge 5 of ó
should olso be exomined. The iop surfoce of the entire field should be lightly scroped with hond
tools to remove ony greose. No chemicols sholl be opplied. Removol using vocuum equipmeni
moy be ottempted, but greot core must be token io prevent excess removol of supporting soils.
Scouring of the fop surfoce with woier pressure might be ottempted, but only if excess removol of
moieriols is prevented. Throughout the process of cleoning lhe top surfoce, disposoble prolective
clolhing, gloves, foce shields ond respirotors sholl be worn by oll personnel to prevent contoct
with woste moteriols. All moteriols removed from the surfoce of the obsorption field sholl be
sofely disposed of in occordonce wilh oll opplicoble Federol, Stote ond locol regulotions.
lf you hove ony queslions, pleose coll me ot (970) 945-2550, extension 206, or by emoil ot:
tcpo ge@gomboen g ineering.com.
Sincerely,
Gombo & Associotes, lnc.
rter Poge,61
Attochments: NONE - previous submittol hod plons.
Cc Simon Cosos, by emoil to: sxc@ospenhospitol.org
Tom Collins, by emoil to: tomcollinsr@iuno.com
Jim Rodo, by emoil lo: irodo@gorfield-county.com
Andy Schwoller, by hond, wiih permit opplicoiion.
H:\07óBl \Systsm 2 Repoirs\Communicolions\System 2 rehobililqtion - Subm¡ïol io GARCO for repoir permil.doc
Heron's Nest RV Pork - Remediolion sleps
Wednesdoy, December 10, 2008
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