Department of the Army
U.S. Army Corps of Engineers
United States Environmental Protection
Agency
' DEC I 2 1996 ' . .
MEMORANDUM TO THE FIELD
SUBJECT: Applicability of Exemptions under Section 404(f) to "Deep-Ripping" Activities in
Wetlands
PURPOSE: The purpose of this memorandum is to clarify the applicability of exemptions provided
under Section 404(f) of the Clean Water Act (CWA) to discharges associated with "deep-ripping"
and related activities in wetlands.1
BACKGROUND:
1. Section 404(£)(1) of the CWA exempts from the permit requirement certain discharges associated
with normal Sinning, forestry, and ranching practices in waters of the United States, mrJuding
wetlands. Discharges into waters subject to the Act associated with fanning, forestry, and ranching
practices identified under Section 404(fXl) do not require a permit except as provided under Section
404
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Department of the Army
U.S. Army Corps of Engineers
United States Environmental Protection
Agency
DEC I S 1996
MEMORANDUM TO THE FIELD
SUBJECT: Applicability of Exemptions under Section 404(f) to "Deep-Ripping" Activities in
Wetlands
PURPOSE: The purpose of this memorandum is to clarify the applicability of exemptions provided
under Section 404{f) of the Clean Water Act (CWA) to discharges associated with "deep-ripping"
and related activities in wetlands.1
BACKGROUND:
1. Section 404(f>(l) of the CWA exempts from the permit requirement certain discharges associated
qifrih normal farming fiwyfry ^1^$ rarvhmg nragrif** in \uxler* ftfth* TTmted State^ inrhiHing
wetlands. Discharges into waters subject to the Act associated with farming, forestry, and ranching
practices identified under Section 404(f)(l) do not require t permh except ^ provided under Section
404(0(2).
2. Section 404(f)(l) does not provide a total, ortc^natic exemption ^afl activities related to
agricultural, silvicultural, or ranching practices. Rather, Sectk»404(fXl) exempt? only those
activities specifically identified in paragraphs (A) through (F), and "other activities of essentially the
same character as named* [44 FR 34264]. For example, Section 404
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4. EPA and Corps regulations [40 CFR 230 and 33 CFR 320] and preamble define in some detail
the specific "normal" activities listed in Section 404(f)(l)(A). Three points may be useful in the
current context: ,
a. As explained in the preamble to the 1979 proposed regulations, the words "such as" have
been consistently interpreted as restricting the section "to the activities named in the statute
and other activities of essentially the same character as named," and "preclude the extension
of the exemption... to activities that are unlike those named." [44 FR 34264].
b. Plowing is specifically defined in the regulations not to include the redistribution of
surface material in a manner which converts wetlands areas to uplands [See 33 CFR
c. Discharges associated with activities that establish an agricultural operation in wetlands
where previously ranching had been conducted, represents a "change in use" within the
meaning of Section 404(f)(2). Similarly, discharges that establish forestry practices in
wetlands historically subject to agriculture also represent a change hi use of the site [See 33
CFR323.4(c)].
5. The statute includes a provision at Section 404(f)(2) that "recaptures" or reestablishes the permit
requirement for those otherwise exempt discharges which:
a. convert an area of the waters of the U.S. to a new use, and
. . , t
b. impair the flow or circulation of waters of the U.S. or reduce the reach of waters of the
U.S. .
Conversion of an area of waters of the U.S. to uplands triggers both provisions (a) and (b) above.
' Thus, at a rninimum, any otherwise exempt discharge that results in the conversion of waters of the
U.S. to upland is recaptured under Section 404(fX2) and requires a permit. It should be noted that
in order to trigger the recapture provisions of Section 404(f)(2), the discharges themselves need not
be the sole cause of the destruction of the wetland or other change in use or sole cause of the
reduction or impairment of reach, flow, or circulation of waters of the U.S. Rather, the discharges
need only be "incidental to" or "part of an activity which is intended to or will forseeably, bring
about that result. Thus, in applying Section 404(f)(2), one must consider discharges in context,
rather than isolation.
ISSUE: .;•'•'
1. Questions have been raised involving "deep-ripping" and related activities in wetlands and
whether discharges associated with these actions fall within the exemptions at Section 404(f)(l)(A).
In addition, the issue has been raised whether, if such activities fall within the exemption, they would
be recaptured under Section 404(f)(2).
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2. "Deep-ripping" is defined as the mechanical manipulation of the soil to break up or pierce highly
compacted, impermeable or slowly permeable subsurface soil layers,, or other similar kinds of
restrictive soil layers. These practices are typically used to break up these subsoil layers (e.g.,
impermeable soil layer, hardpan) as part of the initial preparation of the soil to establish an
agricultural or silvicultural operation. Deep-ripping and related activities are also used in established
farming operations to break up highly compacted soil. Although deep-ripping and related activities
may be required more than once, the activity is typically not an annual practice. Deep-ripping and
related activities are undertaken to improve site drainage and facilitate deep root growth, and often
occur to depths greater than 16 inches and, in some cases, exceeding 4 feet below the surface. As
such, h requires the use of heavy equipment, including bulldozers, equipped with ripper-blades,
shanks, or chisels often several feet in length. Deep-ripping and related activities involve extending
the blades to appropriate depths and dragging them through the soil to break up the restrictive layer.
3. Conversely, plowing is defined in EPA and Corps regulations [40 CFR 230 and 33 CFR 320] as
"aUfonns of primary tillage...used...fcr the breaking up, cutting, turning over, or stirring of soil to
prepare it for the planting of crops" [40 CFR 232.3(d)(4)]. As a general matter, normal plowing .
activities involve the annual, or at least regular, preparation of soil prior to seeding or other planting
activities. According to USD A,plowing generally involves the use of a blade, chisel, of series of
blades, chisels, or discs, usually 8-10 inches in length, pulled behind a. farm vehicle to prepare the soil
for the planting of annual crops or to support an ongoing farming practice. Plowing is commonly
used to break up the surface of the soil to ^faftM" soil tilth tnd to facilitate infiltration thrwglKoMt
the upper root zone. ..
DISCUSSION:
1. Plowing in wetlands is exempt from regulation consistent with the following circumstances:
a. it is conducted as part of an ongoing, established agricultural, sflvkuftural, or ranching
operation; and ! .
b. the activity is consistent with the definition of plowing in EPA and Corps regulations [40
CFR 230 and 33 CFR 320}; and
c. the plowing is not incidental to an activity that results in the immediate or gradual
conversion of wetlands to non-waters.
2, Deep-ripping and related activities are distinguishable from plowing and similar practices (e.g.,
discing, harrowing) with regard to the purposes and circumstances under which it is conducted, the
nature of the equipment that is used, and its effect, including in particular the impacts to the
hydrology of the site. -.'•'..
a. Deep-ripping and related activities are commonly conducted to depths exceeding 16
inches, and as deep as 6-8 feet below the soil surface to break restrictive soil layers and
improve water drainage at sites that have not supported deeper rooting crops. Plowing
depths, according to USD A,rarely exceed one foot into the soil and not deeper than 16
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inches without the use of special equipment involving special circumstances. As such, deep-
ripping and related activities typically involve the use of specialized equipment, including
heavy mechanized equipment and bulldozers, equipped with elongated ripping blades, shanks,
or chisels often several feet in length. Moreover, while plowing is generally associated with
ongoing operations, deep-ripping and related activities are typically conducted to prepare a
she for establishing crops not previously planted at the she. Although deep-ripping may have
to be redone at regular intervals in some circumstances to tnaintflin proper soil drainage, the
activity is typically not an annual or routine practice.
b. Frequently, deep-ripping and related activities are conducted as a preliminary step for
converting a "natural" system or for preparing «-yig*i«*vi for a new use such as farming or.
silviculture. In those instances, deep ripping and related activities are often required to break
up naturally-occurring impermeable or slowly permeable subsurface soil layers to facilitate
proper root growth. For example, for certain depresstonal wetlands types such as vernal
pools, the silica-cemented hardpan (durapan) or other restrictive layer traps precipitation and
seasonal runoff creating ponding and saturation conditions at the soil surface. UK presence
of these impermeable or slowly permeable subsoil layers is essential to support the hydrology
of the system. Once these layers are disturbed by activities such as deep-ripping^ the
hydrology of the system is disturbed and the wetland is often destroyed.
c. In contrast, there are other dranmt ancet where tctwH^f *** «« mpaction of the sofl below the soil surface. It may be
necessary to break up, on a regular although not annual basis, these restrictive layers in order
to tUow f(x iKmmal roc»t devetofraient ai^ inffltratioflL Such activities may require special
equipment and can sometimes occur to depths greater than 16 inches. However, because of
particular physical conditions, including this presence of a water table at or near the surface
for part of the growing season, the activity typically does nc< have the eflfect of impairing the
hydrology of the system or otherwise altering the wetland characteristics of the site.
CONCLUSION:
1. When deep-ripping and related activities are undertaken as part of an established, ongoing
agricultural, siivtcuhural, or ranching operation, to break up cmnpacted soil layers ajjd where the
hydrology of the she win not be altered such that h would result in conversion of waters of the U.S.
to upland, such activities are exempt under Section 404{fXlXA)-
2. Deep-ripping and related activities in wetlands are afc part of a nonnal, ciigoiiig activity, and
therefore nflj exempt, when such practices are conducted in association whli efforts to establish for
the first time (or when a previously established operation was abandoned) an agricultural,
silvicuhural or ranching operation. In addition, deep-ripping and related activities are not exempt in
circumstances where such practices would trigger the "recapture" provision of Section 404(f)(2):
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a) Deep-rippingto establish a farming operation at a she where a ranching or forestry
operation was in place is a change in use of such a she. Deep-ripping and related activities
that abb have the effect of altering or removing the wetland hydrology of the site would
trigger Section 404(fX2) and such ripping would require a permit
b) Deep-ripping a site that has the effect of converting wetlands to non-waters would also
trigger Section 404(fX2) and such ripping would require a permit.
3. It is the agencies' experience that certain wetland types are particularly vulnerable to hydrdogical
alteration as a result of deep-ripping and related activities. Depressional wetland systems such as
prairie potholes, vernal pools and playas whose hydrology is critically dependent upon the presence
of an impermeable or slowly permeable subsofl layer are particularly sensitive to disturbance or
alteration of thb subsoil layer. Based upon this experience, the agencies have concluded that, as a
general matter, deep-ripping and similar practices, cc«sisteittwi& the description abc^ conducted
in prairie potholes, vernal pools, playas and similar depressional wetlands destroy the hydrological
integrity of these wetlands. In these drcummtancra, deep-ripping in prairie potholes, vernal pools, •
and playas is recaptured under Section 404(fX2) and requires a permit under the Clean Water Act.
Robert H. Wayland ffl
Director
Office of Wetlands, Oceans and Watersheds
U.S. Environmental Protection Agency
Daniel R. Burnt, P.E.
ChkC Operation!, Construction
and Readiness Division
Directorate of CM! Work*
U.S. Army Corps of Engineers
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