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CU
YAH
OG
A CO
UN
TY BO
ARD O
F HEA
LTH5550 Venture D
riveParm
a, Ohio 44130
Tel:216.201.2020
Fax:216.676.1317
ww
w.C
CBH
.net
Hom
eow
ner’s
Guid
e toH
OU
SEHO
LD SEW
AG
ETREATM
ENT SYSTEM
S
Sew
ag
e S
yste
m M
ain
ten
an
ce R
eco
rdD
ate o
f Clea
nin
g,
Service or In
spectio
nM
ain
tenance C
ontra
ctor / Telep
hone N
um
ber
The printing of this document w
as funded by the Lake Erie Protection Fund.
CU
YA
HO
GA
CO
UN
TY B
OA
RD
OF H
EALTH
5550 Ve
ntu
re D
rive • P
arm
a, O
hio
44130P
ho
ne
: 216-201-2001 • Fax: 216-676-1317
ww
w.C
CB
H.n
et
Water Q
uality
Pro
gra
mW
ater Q
uality
Pro
gra
mYo
ur Sew
age Sy
stem IS YO
UR RESPO
NSIBILITY
Your Sew
age Sy
stem IS YO
UR RESPO
NSIBILITY
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Did
yo
u k
no
w that as a hom
eowner you’re responsible for m
aintaining your sewage
system? D
id you know that m
aintaining your sewage system
protects your investment in your hom
e? Did you
know that you should periodically inspect your system
and pump out your septic tank? If properly designed,
constructed and maintained, your sew
age system can provide long-term
, effective treatment of household
wastew
ater. If your sewage system
isn’t maintained, you m
ight need to replace it, costing you thousands ofdollars. A
malfunctioning system
can contaminate both groundw
ater that might be a source of drinking w
ateras w
ell as surface water. A
nd if you sell your home, your sew
age system m
ust be in good working order.
This guide will help you care for your sew
age system. It w
ill help you understand how your system
works and
what steps you can take as a hom
eowner to ensure your system
will w
ork properly. To help you learn more,
consult the resources that are listed throughout this booklet. A helpful checklist is also included at the end of
the booklet to help you keep track of your sewage system
maintenance.
·D
o n
ot build anything over or w
ithin ten feet of any partof your sew
age system.
·D
o n
ot allow
anyone to drive heavy vehicles like cars ortrucks over any portion of the system
. Pipes and tanksm
ay be damaged or crushed. The soil in the filtration or
leaching field may be com
pacted, which w
ould minim
izeits ability to filter and absorb sew
age.
·D
o n
ot plant any shallow
rooted trees or shrubs, likew
illows or soft m
aples, near any portion of the system.
Their roots will grow
and travel laterally underground. As they
seek water, they can grow
into pipes causing blockages.
TOP TH
REE TH
ING
S YO
U C
AN
DO
TO P
RO
TECT Y
OU
R SEW
AG
E SYSTEM
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
The Cuyahoga C
ounty Board of Health conducts an extensive w
ater quality program. The focus of this
program is an overall w
atershed based approach when dealing w
ith water quality issues. A
ctivities within this
program include:
·Identifying and elim
inating public health nuisances and hazards in our surface waters
·Surveying the various w
atersheds throughout the county·
Supporting the Household Sew
age, Storm W
ater, Semi-public Sew
age, Bathing Beach and Parks&
Recreation Programs
·Educating the public on N
on-Point Source Pollution issues·
Participating in local watershed protection groups and m
eetings
Stream
Monito
ring
The Board of Health has conducted a stream
monitoring program
since the late 1980’s. This program allow
sfor the chem
ical and biological monitoring of w
ater quality in our watersheds. The inform
ation collected fromthis program
has documented the need for the Board of H
ealth’s Operation and M
aintenance Program for
Household Sew
age Treatment System
s. To date, thousands of water quality sam
ples have been collected.Likew
ise, over 50 permanent w
ater quality monitoring sites have been established w
ithin the variousw
atersheds in Cuyahoga C
ounty. This data is used to obtain general baseline conditions and to identifyproblem
areas potentially being impacted by sources of w
ater pollution.
The Board of Health also em
ploys college interns over the summ
er months to perform
various studies onspecific sub-w
atersheds. These studies enable college students with an interest in environm
ental health theopportunity to receive real w
ork experience by performing
biological and chemical m
onitoring of surface waters. If
you would like m
ore information about this program
or areinterested in becom
ing an intern, please contact the Boardof H
ealth.
Stream
Surveys
Intensive surveys are performed on specific w
atersheds.Survey m
ethods include:·
Bacteriological and chemical analysis
·M
acroinvertebrate sampling
·Q
ualitative Habitat Evaluation Index (Q
HEI) analysis
·H
eadwater H
abitat Evaluation Index (HH
EI) analysis
How
does m
y sew
age sy
stem w
ork
?H
ow
does m
y sew
age sy
stem w
ork
?O
pera
tion a
nd M
ain
tenance P
rogra
mO
pera
tion a
nd M
ain
tenance P
rogra
m
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Pipe from
the home
All of your household w
astewater flow
s through your plumbing and exits your hom
e through a pipeto the septic tank. The contents of this sew
er pipe should include the wastew
ater from all of the drains
inside the home - sinks, toilets, show
ers, utility tubs, etc. Stormw
ater or groundwater that does not
need to be treated by the sewage system
should not enter this pipe. Drainage from
downspouts, sum
ppum
ps, etc. will send too m
uch water to the system
and possibly shorten its lifespan.
Septic ta
nkThe septic tank perform
s the first step of the wastew
ater treatment process. The septic tank is a solid
watertight tank designed specifically to accept all w
astewater from
the home. Som
e installations may
have one tank or two tanks in series. A
ll tanks should feature inlet and outlet baffles, along with an
access manhole for cleaning.
The inlet baffle ensures that entering wastew
ater mixes w
ith the liquid contents of the tank to beginbacterial breakdow
n of organic materials and separation of solids. The inlet baffle also prevents the
floating scum layer from
floating back and clogging the inlet pipe.
The outlet baffle ensures that only liquid is able to leave the tank and enter the secondary treatment portion
of your system. If the scum
layer reaches the outlet pipe, the pipe would quickly becom
e plugged.
The co
nten
ts of th
e septic ta
nk
stratifies in
to th
ree layers:
·Floating Scum
Layer - soaps, greases, toilet paper, etc.·
Liquid layer - water, other liquids, and suspended solids
·Sludge - heavy organic and inorganic m
aterials settle to the bottom of the tank.
Bacteria that naturally occur in the sewage w
hich enters the tank are necessary to break down
organic materials in w
astewater. This is often referred to as prim
ary treatment. Pathogens in the w
asteare not destroyed in the septic tank. The septic tank and its bacteria prepare the w
astewater for
treatment by the rem
ainder of your system.
THECOMPONENTS
TIPTo prevent buildup, sludge and floating scum
need to berem
oved through periodic pumping of the septic tank.
County regulations require that septic tanks be pum
pedout at least once every three years. If you have alarge fam
ily you probably need to have it pumped
more often.
The access lid for your septic tank is required to be kept tograde. This allow
s the tank to be easily located, pumped,
and inspected. If your tank is not to grade, an extensionriser can be installed at the tim
e of your next cleaning.
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Along w
ith requested point of sale inspections and complaint investigations, the C
uyahoga County Board of H
ealthconducts operational m
aintenance inspections of home sew
age treatment system
s throughout the health district.Since the effluent from
home sew
age systems has been identified as a m
ajor contributor to non-point sourcepollution in our w
aterways, an on-going inspection and m
aintenance program is a necessity.
Since the inception of the Operation and M
aintenance Program, m
any educational seminars have been conducted
for homeow
ners who utilize household sew
age systems. The Board of H
ealth continues to stress homeow
nereducation as the key to a successful O
peration and Maintenance Program
. Countyw
ide stream m
onitoring andsam
pling of surface water continue to assist in prioritizing areas determ
ined to be adversely impacted by pollution
sources. Many of the sew
age systems in use today are of an antiquated design and w
ere installed over 30 yearsago. Evaluation results have show
n that less than a third of these older systems are operating in a satisfactory
manner. M
ost are not capable of properly treating and disposing of the household wastew
ater generated on adaily basis. This results in several hundred gallons of partially treated effluent, or in som
e cases, raw sew
ageleaving each failing system
every day. To help identify and eliminate these sources of pollution, sew
age systemevaluations continue to be scheduled and conducted in com
munities throughout C
uyahoga County.
Work
ing with Com
munities
The Operation and M
aintenance Program encom
passes an overall water quality and w
atershed based approachin hopes of m
inimizing w
ater quality problems em
anating from failing household sew
age systems. A
s sewage
systems are evaluated in a com
munity, the data gathered is provided to local officials. This inform
ation can then beutilized to help determ
ine the most effective m
eans of eliminating pollution sources in a specific area. In m
anycircum
stances, the design and installation of a sanitary sewer is a feasible solution for elim
inating failing sewage
systems. W
here sanitary sewers are determ
ined not to be feasible, the repair or replacement of failing hom
esew
age treatment system
s will be on going.
Many m
unicipalities have completed prelim
inary studies and have determined that the installation of sanitary sew
ersin sections of their com
munities is not feasible. Topographical lim
itations, large lot sizes or frontages, and sparsepopulation in an area m
ay result in a sewer project not being practical. In these com
munities, the Board of H
ealthcontinues to collaborate w
ith homeow
ners to repair or replace failing home sew
age treatment system
s. To date,several thousand failing or im
properly working sew
age treatment system
s have either been repaired or replacedthroughout C
uyahoga County. These activities have resulted in dram
atic improvem
ent in the water quality in those
areas. In many cases, the cost to hom
eowners for the construction of a sanitary sew
er is often comparable to the cost
of replacing the existing sewage treatm
ent system. Likew
ise over 4000 systems have been elim
inated from use as a
result of the installation of sanitary sewers since the inception of the O
peration and Maintenance Program
.
The Cuyahoga C
ounty Board of Health has also developed a regional storm
water program
to assist our 55designated Phase II Storm
Water C
omm
unities within our jurisdiction, and to also assist com
munities throughout the
State of Ohio. This program
was created and expanded from
our existing Household Sew
age Operation and
Maintenance Program
and Water Q
uality Monitoring Program
s. This program allow
s the Board of Health to
provide specific functions for these comm
unities to assist them in reaching their Storm
Water M
anagement Program
Goals. These activities includes educational outreach and participation, illicit discharge detection, M
S4 inventories,dry w
eather flow surveys, w
ater quality monitoring of M
S4 outfalls and investigative activities to locate illicitsources of pollution to a com
munities M
S4 system.
What a
re OFF-LO
T and
ON
-LOT
Househ
old
Sewage Trea
tmen
t System
s?W
hat a
re OFF-LO
T and
ON
-LOT
Househ
old
Sewage Trea
tmen
t System
s?
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
There is a misconception that all H
ousehold Sewage Treatm
ent Systems are leachfields. Leachfields
function as “on-lot” systems w
here the wastew
ater flows from
the septic tank into the soil. The wastew
aterpercolates into the soil, w
hich provides final treatment by rem
oving harmful bacteria, viruses, and
nutrients. Suitable soil is necessary for successful wastew
ater treatment.
In Cuyahoga C
ounty, and much of O
hio, the soils are too severe to allow for proper percolation into
the ground. The soils will not accept these volum
es of water and can not provide the necessary treatm
ent.For this reason, the m
ajority of systems used in the past in this area are “off-lot” sew
age treatment
systems. These system
s are designed to discharge the treated effluent from the sew
age system back into
the environment via a creek, storm
sewer or ditch.
Filter Bed
sA
lthough their design may have changed over the years, filter bed system
s have been installed in Cuyahoga
County for decades. Filter beds installed prior to the early 1970’s typically utilized gravel as a filtration
media. These older beds consisted of clay tile pipes laid on top of a 15 to 24 inch thick bed of large
gravel. A clay tile line w
as also placed below the gravel bed to act as a collection pipe. W
astewater from
the septic tank would drain into the top pipes, filter through the gravel and be collected in the bottom
line.This effluent w
as then discharged to the environment. M
any of these systems are still in use today.
Unfortunately, these old gravel beds did not function w
ell and did not have the ability to properly filter thesew
age prior to discharging it to a ditch, stream or storm
sewer. For this reason, approved filter sand has
been utilized as the actual filtration media in m
ore modern filter bed system
s. Perforated pipe is laid ingravel both above and below
the filter sand. The sand has a filtration capability that is far superior to thatof gravel.
Filter bed systems installed in the last few
decades typically use a splitter box, also know as a distribution
box. This box contains a flow diversion device that directs the flow
of wastew
ater to one side of the filterbed or the other. This allow
s one part of the bed to rest, while the other is in use. This m
ay help extendthe life span of your filter bed system
. The flow diverter should be sw
itched to alternate flow at least
annually. For this reason, the flow diversion box m
ust be kept to grade. If you do not know w
here it islocated, contact your septic pum
per, installer, or the Board of Health.
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Hig
h-efficien
cy to
ilets and
show
erhea
ds
Toilet use accounts for 25 to 30 percent of household water use. D
o you know how
many gallons of w
ateryour toilet uses to em
pty the bowl? M
ost older homes have toilets w
ith 3.5 to 5-gallon reservoirs, while new
erhigh-efficiency toilets use 1.6 gallons of w
ater or less per flush. If you have problems w
ith your sewage system
being flooded with household w
ater, consider reducing the volume of w
ater in the toilet tank if you don’t havea high-efficiency m
odel. The use of high-efficiency showerheads can also dram
atically minim
ize the volume of
water the system
receives on a daily basis.
Pro
ducts n
ot to
be p
ut in
to yo
ur sew
age system
Even though sewage system
s thrive on wastew
ater, certain chemicals can harm
the delicate balance in aseptic tank and should not be run through the system
. They include:
·Paints, thinners, and solvents
·D
rain cleaners·
Motor oil, kerosene and gasoline
·Floor w
ax and chlorine bleach
Other m
aterials may not chem
ically harm the system
, but may cause a blockage or clog pipes. These item
sw
ill not break down and can not be digested by m
icroorganisms. The follow
ing materials should never be
flushed down the toilet or run dow
n the drain:
·G
rease, cooking oil and animal fat
·C
otton balls and cotton swabs
·Sanitary napkins and tam
pons·
Condom
s·
Plastics·
Coffee grounds
Garb
age d
isposa
lsElim
inating the use of a garbage disposal can reduce the amount of grease and solids entering the septic
tank and possibly clogging components of your sew
age system. A
garbage disposal grinds up kitchenscraps, suspends them
in water, and sends the
mixture to the septic tank. O
nce in the septictank, som
e of the materials are broken dow
n bybacterial action, but m
ost of the grindings flowthrough the tank and into the secondary treatm
entcom
ponent of your sewage system
. This can causefilter beds and filters in aeration units to clog.
USE W
ATER
EFFICIEN
TLY!
• Install high-efficiency toilets and showerheads
• Fill the bathtub with only as m
uch water as you need
• Turn off faucets while shaving or brushing your teeth
• Run the dishwasher and clothes w
asher only when they’re full
• Use toilets to flush sanitary w
aste only (not kitty litter, diapers, or other trash)
• Make sure all faucets are com
pletely turned off when not in use
• Maintain your plum
bing to eliminate leaks
• Install aerators in the faucets in your kitchen and bathroom
HO
W D
O I m
ain
tain
my sew
age sy
stem?
Savin
g M
oney
A key reason to m
aintain your sewage system
is to save money!
Failing septic systems are expensive to repair or replace, and poor
maintenance is often the culprit. Your system
will need routine pum
ping.Pum
ping frequently will depend on how
many people live in the
house and the size of the system. A
non-functioning sewage system
can lower your property value and could pose a legal liability.
Pro
tecting h
ealth
and th
e enviro
nm
ent
Other reasons for safe treatm
ent of sewage include preventing the spread of infection or disease and
protecting water resources. Typical pollutants in household w
astewater include nitrogen, phosphorus, and
disease-causing bacteria and viruses. If a sewage system
is working properly, it w
ill effectively remove m
ost ofthese pollutants.
With one-fourth of U
.S. homes currently using household sew
age systems, m
ore then 4 billion gallons ofw
astewater per day is dispersed below
the ground surface or into the surface waters. O
ver a million sew
agesystem
s are currently in use in the state of Ohio. Inadequately treated sew
age from these system
s can be acause of groundw
ater and surface water contam
ination. It poses a significant threat to drinking water and
human health because it can contam
inate drinking water w
ells and cause diseases and infections in peopleand anim
als. Improperly treated sew
age that contaminates nearby surface w
aters also increases the chance ofsw
imm
ers contracting a variety of infectious diseases. These range from eye and ear infections to acute
gastrointestinal illnesses and hepatitis.
Insp
ect and p
um
p freq
uen
tlyYou should have your sew
age system pum
ped once every three years. If you have an aeration system, you
should consider obtaining a service contract from the distributor of that particular system
. This maintenance
contract allows for routine inspections of all m
echanical components of your system
. For newer filter bed
systems, the beds should be alternated on an annual basis at the distribution box. This allow
s for thealternating of the beds and w
ill provide optimal life expectancy for your filter bed system
. If you do notknow
where this box is located, contact the Board of H
ealth for assistance.
Use w
ater efficien
tlyA
verage indoor water use in the typical single-fam
ily home is alm
ost 70 gallons per person per day. Leakysinks and toilets can w
aste as much as 200 gallons each day. The m
ore water a household conserves, the less
water enters the sew
age system. Efficient w
ater use can improve the operation of the sew
age system and
reduce the risk of failure.
HO
W D
O I m
ain
tain
my sew
age sy
stem?
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Aera
tion Sy
stems
If you utilize a home aeration system
, special care is required. The motor, w
hich provides aeration to thesystem
, must operate continuously. If it does not, the oxygen required by the m
icroorganisms that thrive
in the aeration system w
ill not be sufficient and they will begin to die. These “sew
age bugs” help to breakdow
n the organic matter in the w
astewater and biologically convert it to stable substances in the form
ofgases and liquids. The aeration and m
ixing of the wastew
ater ensures that it comes in contact w
ith them
icroorganisms so thorough treatm
ent can occur.
Several aeration system designs also incorporate the use of filters to provide additional treatm
ent. Thesefilters need to be checked and cleaned on a routine basis to w
ork effectively. If these filters become
clogged, then the wastew
ater has no place to travel within that system
. This can cause a possible backup.It can also cause solids to clog the m
otor, shortening its life span. Untreated w
aste may eventually leave
the system and enter the environm
ent.
Aeration system
s have mechanical com
ponents, which w
ill also need to be serviced and eventuallyreplaced. Since m
uch of the additional care and maintenance required w
ith these systems is beyond the
expertise of the average homeow
ner, various companies have been certified by the original m
anufacturersto offer extended service contracts.
. . . ha
ve
an
ala
rm b
ox
tha
t is
situ
ate
d in
a
con
spicu
ou
s loca
tion
iny
ou
r ho
me
.
•A
n alarm w
ill typicallysound if a m
otor is notoperating or if you arehaving a backup w
ithinthe tank.
•O
nce this alarm sounds,
you should contact theservice provider w
hosenam
e appears on thealarm
box.
MO
DERN
AERATIO
N SYSTEM
S•
You should also conservew
ater usage until atechnician arrives torepair your system
.
•You can still flush yourtoilets and use w
atersparingly during this tim
e.
•Refrain from
washing
laundry or conductingother activities thatgenerate a large volum
eof w
astewater.
A b
ack
up
into
yo
ur h
om
e or p
on
din
g o
fw
astew
ater o
n y
ou
r law
n co
uld
result.
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
When sew
age systems are properly designed,
constructed, and maintained, they effectively
reduce or eliminate m
ost human health or environm
ental
threats posed by pollutants in household wastew
ater.
How
ever, they require regular maintenance or they can
fail. Sewage system
s need to be monitored to ensure that
they work properly throughout their service lives.
WH
Y SHO
ULD
I main
tain
my sew
age sy
stem?
WH
Y SHO
ULD
I main
tain
my sew
age sy
stem?
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Leach
fields
The typical sewage system
installed throughout the country for decades has utilized a septic tank and aleaching tile field. By design, the sew
age flows out of the tank and into either a clay tile or perforated pipe
that is laid in trenches. The wastew
ater then drains from the pipes and enters the soil w
here it must be filtered
and absorbed. This effluent must be properly filtered so that it does not pose a threat to ground w
ater.
Leaching tile fields work w
ell in areas with w
ell drained, sandy soils. Unfortunately, m
uch of Cuyahoga
County consists of relatively poorly drained clay soils. These soils typically have little absorption capacity.
The soil permeability - the rate at w
hich water percolates into the soil - is very slow
. Poorly drained soilsare typically saturated w
ith water during w
et weather and stay w
et for long periods of time after a
heavy rain.
Leaching tile fields are designed to keep all of the effluent on lot. If your system utilizes a leachfield and is
instead discharging off lot, your system is not operating properly. Leachfields w
ill fail once the soil canno longer absorb the w
ater that is being sent there from the septic tank. O
nce this occurs, the wastew
ater will
either pond on top of the ground or find an alternative path and be discharged onto the ground at anotherlocation.
Evapotra
nsp
iratio
n Field
s (E-T)A
n evapotranspiration system, or shallow
leaching system, receives effluent from
the septic tank anddisposes of it by a com
bination of evaporation at the soil surface and transpiration to plants. There isalso dissipation into the soil, but it can be lim
ited depending on the severity of the soil structure.
The evapotranspiration system design incorporates a large leaching field preceded by an aeration system
or mounded sand filter bed. The trenches are shallow
to allow for the evaporation and transpiration of the
treated wastew
ater. The best soil available is typically near the surface, where the plant roots are located.
HO
MEO
WN
ER’S GU
IDE TO
HO
USEH
OLD
SEWA
GE TREATM
ENT SYSTEM
S
Mounds
A septic tank m
ound system can be utilized for treating and disposing of dom
estic wastew
ater in areasunsuitable for conventional septic tank soil absorption system
s. Mounds are pressure-dosed sand filters
placed above, and discharging directly to, the natural soil. Their main purpose is to provide additional
treatment to the w
astewater before it enters the natural environm
ent. Mound system
s are designed toovercom
e site restrictions such as:
·Soils that have a very slow
or extremely rapid perm
eability·
Shallow soil cover over creviced or porous bedrock
·A
high water table.
The three components of a m
ound system are a pretreatm
ent unit(s), dosing chamber, and the elevated
mound. The pretreatm
ent unit is usually a septic tank, which rem
oves solids from the w
astewater. A
naeration system
may also be utilized to im
prove the quality of wastew
ater reaching the mound. The dosing
chamber follow
s the septic tank and contains a pump, w
hich uses pressure to evenly distribute the wastew
aterover the infiltration surface of the m
ound. The mound is m
ade up of a soil cover that can support vegetation.Below
the soil is a fabric-covered coarse gravel aggregate in which a netw
ork of small diam
eter perforatedpipe is placed. The netw
ork of perforated pipe is designed to distribute the effluent evenly through the gravel.H
ere it trickles down to the sand m
edia and hence, into the plowed basal area (natural soil). Treatm
entoccurs through physical, biological, and chem
ical means as the w
astewater filters dow
n through the sandand the natural soil.
Drip
Irrigatio
nIn a drip irrigation system
the wastew
aterleaves the pretreatm
ent unit and is pumped to a
series of small diam
eter distribution piping.Several ounces of w
astewater leave the piping
through many em
itter openings spaced evenlythroughout the system
. This allows for frequent,
low pressure applications of the treated
wastew
ater to the top layer of the soil, which is
the most biologically active zone. This system
can be utilized to overcome a num
ber of sitelim
itations and can potentially allow som
edifficult lots to be developed.