ASTM D5921-96(2010)
(Practice)Standard Practice for Subsurface Site Characterization of Test Pits for On-Site Septic Systems (Withdrawn 2019)
Standard Practice for Subsurface Site Characterization of Test Pits for On-Site Septic Systems (Withdrawn 2019)
SIGNIFICANCE AND USE
This practice should be used as part of the evaluation of a site for its potential to support an on-site septic system in conjunction with Practice D5879 and Practice D5925.
This practice should be used after applicable steps in Practice D5879 have been performed to document and identify potentially suitable field areas.
This practice should be used by those who are involved with the evaluation of properties for the use of on-site septic systems. They may be required to be licensed, certified, meet minimum educational requirements by the area governing agencies, or all of these.
This practice requires exposing the soil to an appropriate depth (typically 1.5 to 1.8 m, or greater as site conditions or project objectives require) for examining the soil morphologic characteristics related to the performance of on-site septic systems.
SCOPE
1.1 This practice covers procedures for the characterization of subsurface soil conditions at a site as part of the process for evaluating suitability for an on-site septic system. This practice provides a method for determining the usable unsaturated soil depth for septic tank effluent to infiltrate for treatment and disposal.
1.2 This practice describes a procedure for classifying soil by field observable characteristics within the United States Department of Agriculture, Soil Conservation Service (SCS) classification system. The SCS classification system is defined in Refs (1–4), not in this practice. This practice is based on visual examination and manual tests that can be performed in the field. This practice is intended to provide information about soil characteristics in terms that are in common use by soil scientists, public health sanitarians, geologists, and engineers currently involved in the evaluation of soil conditions for septic systems.
1.3 This procedure can be augmented by Test Method D422, when verification or comparison of field techniques is required. Other standard test methods that may be used to augment this practice include: Test Methods D2325, D3152, D5093, D3385, and D2434.
1.4 This practice is not intended to replace Practice D2488 which can be used in conjunction with this practice if construction engineering interpretations of soil properties are required.
1.5 This practice should be used in conjunction with D5879 to determine a recommended field area for an on-site septic system. Where applicable regulations define loading rates-based soil characteristics, this practice, in conjunction with D5925, can be used to determine septic tank effluent application rates to the soil.
1.6 This practice should be used to complement standard practices developed at state and local levels to characterize soil for on-site septic systems.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.9 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Nat all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.
WITHDRAWN RATIONALE
This practice covers procedures for the characterization of subsurface soil conditions at a site as part of the ...
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D5921 − 96 (Reapproved 2010)
Standard Practice for
Subsurface Site Characterization of Test Pits for On-Site
Septic Systems
This standard is issued under the fixed designation D5921; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Many State and local jurisdictions have requirements for evaluating sites for approval of on-site
septic systems. This practice provides a method to describe and interpret subsurface characteristics to
evaluate sites for septic systems.All characteristics used in this practice influence the ability of a site
to provide treatment and disposal of septic tank effluent. However, this practice is not meant to be an
inflexible description of investigation requirements. State and local jurisdictions may require fewer or
greater numbers of subsurface features to evaluate a site.
This practice primarily follows the U.S. Department of Agriculture, Soil Conservation Service
(SCS) soil classification system, which encompasses a systematic framework for soil morphological
characterization. The SCS classification the most prevalent system in use for on-site septic systems.
This practice can be complemented by application of other soil description techniques as appropriate,
such as the Unified Soil Classification System (D2485).
1. Scope 1.3 ThisprocedurecanbeaugmentedbyTestMethodD422,
whenverificationorcomparisonoffieldtechniquesisrequired.
1.1 This practice covers procedures for the characterization
Other standard test methods that may be used to augment this
of subsurface soil conditions at a site as part of the process for
practice include:Test Methods D2325, D3152, D5093, D3385,
evaluatingsuitabilityforanon-sitesepticsystem.Thispractice
and D2434.
provides a method for determining the usable unsaturated soil
depth for septic tank effluent to infiltrate for treatment and
1.4 This practice is not intended to replace Practice D2488
disposal. whichcanbeusedinconjunctionwiththispracticeifconstruc-
tion engineering interpretations of soil properties are required.
1.2 This practice describes a procedure for classifying soil
by field observable characteristics within the United States
1.5 This practice should be used in conjunction with D5879
Department of Agriculture, Soil Conservation Service (SCS)
to determine a recommended field area for an on-site septic
classificationsystem. TheSCSclassificationsystemisdefined
system. Where applicable regulations define loading rates-
in Refs (1–2), not in this practice. This practice is based on
based soil characteristics, this practice, in conjunction with
visual examination and manual tests that can be performed in
D5925, can be used to determine septic tank effluent applica-
thefield.Thispracticeisintendedtoprovideinformationabout
tion rates to the soil.
soil characteristics in terms that are in common use by soil
1.6 This practice should be used to complement standard
scientists, public health sanitarians, geologists, and engineers
practices developed at state and local levels to characterize soil
currentlyinvolvedintheevaluationofsoilconditionsforseptic
for on-site septic systems.
systems.
1.7 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
standard.
Rock and is the direct responsibility of Subcommittee D18.01 on Surface and
Subsurface Characterization.
1.8 This standard does not purport to address all of the
Current edition approved May 1, 2010. Published September 2010. Originally
safety concerns, if any, associated with its use. It is the
ε1
approved in 1996. Last previous edition approved in 2003 as D5921 – 96 (2003) .
responsibility of the user of this standard to establish appro-
DOI: 10.1520/D5921-96R10.
In 1995, the name of the SCS was changed to Natural Resource Conservation
priate safety and health practices and determine the applica-
Service.ThisguideusesSCSratherthanNRCSbecausereferenceddocumentswere
bility of regulatory limitations prior to use.
published before the name change.
1.9 This practice offers a set of instructions for performing
The boldface numbers given in parentheses refer to a list of references at the
end of the text. one or more specific operations. This document cannot replace
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5921 − 96 (2010)
education or experience and should be used in conjunction excessive slope, unsuitable landscape position, proximity to
withprofessionaljudgment.Natallaspectsofthispracticemay water supplies, and applicable setbacks have been excluded.
be applicable in all circumstances. This ASTM standard is not
3.1.5 recommendedfieldarea—theportionofthepotentially
intended to represent or replace the standard of care by which
suitable field area at a site that has been determined to be most
the adequacy of a given professional service must be judged,
suitable as a septic tank soil absorption field or filter bed based
nor should this document be applied without consideration of
on surface and subsurface observations.
a project’s many unique aspects. The word “Standard” in the
3.1.6 unsaturated—soil water condition at which the void
title of this document means only that the document has been
spaces that are able to be filled are less than full.
approved through the ASTM consensus process.
3.1.7 vertical separation—the depth of unsaturated, native,
undisturbedsoilbetweenthebottomofthedisposalcomponent
2. Referenced Documents
of the septic system and the limiting depth.
2.1 ASTM Standards:
D422 Test Method for Particle-Size Analysis of Soils
4. Summary of Practice
D653 Terminology Relating to Soil, Rock, and Contained
4.1 This practice describes a field technique using visual
Fluids
examination and simple manual tests for characterizing and
D2325 Test Method for Capillary-Moisture Relationships
evaluating soils and identifying any limiting depth.
for Coarse- and Medium-Textured Soils by Porous-Plate
Apparatus (Withdrawn 2007) 5. Significance and Use
D2434 Test Method for Permeability of Granular Soils
5.1 This practice should be used as part of the evaluation of
(Constant Head) (Withdrawn 2015)
a site for its potential to support an on-site septic system in
D2488 Practice for Description and Identification of Soils
conjunction with Practice D5879 and Practice D5925.
(Visual-Manual Procedure)
5.2 This practice should be used after applicable steps in
D3152 Test Method for Capillary-Moisture Relationships
Practice D5879 have been performed to document and identify
for Fine-Textured Soils by Pressure-MembraneApparatus
potentially suitable field areas.
(Withdrawn 2007)
D3385 Test Method for Infiltration Rate of Soils in Field
5.3 This practice should be used by those who are involved
Using Double-Ring Infiltrometer
with the evaluation of properties for the use of on-site septic
D5093 Test Method for Field Measurement of Infiltration
systems. They may be required to be licensed, certified, meet
Rate Using Double-Ring Infiltrometer with Sealed-Inner
minimum educational requirements by the area governing
Ring
agencies, or all of these.
D5879 PracticeforSurfaceSiteCharacterizationforOn-Site
5.4 Thispracticerequiresexposingthesoiltoanappropriate
Septic Systems
depth (typically 1.5 to 1.8 m, or greater as site conditions or
D5925 Practice for Preliminary Sizing and Delineation of
project objectives require) for examining the soil morphologic
Soil Absorption Field Areas for On-Site Septic Systems
characteristics related to the performance of on-site septic
(Withdrawn 2005)
systems.
3. Terminology
6. Limitations
3.1 Definitions: 6.1 The water content of the soil will affect its properties.
3.1.1 limiting depth—for the purpose of determining suit-
Thesoilshouldbeevaluatedinthemoistconditionbecausethe
abilityforon-sitesepticsystems,thedepthatwhichtheflowof normaloperatingstateofthesepticsystemisamoistcondition.
water, air, or the downward growth of plant roots is restricted.
If the soil is dry, moisten it.
3.1.2 mottle—spots or blotches of different colors or shades
6.2 This practice is not applicable to frozen soil.
of color interspersed with the dominant color (3).InSCS (4)
6.3 Optimum lighting conditions for determining soil color
practice mottles associated with wetness in the soil are called
are full sunlight from mid-morning to mid-afternoon. Less
redox concentrations or redox depletions.
favorable lighting conditions exist when sun is low or skies are
3.1.3 pocket penetrometer—a hand operated calibrated
cloudy or smoky. If artificial light is used, it should be as near
spring instrument used to measure resistance of the soil to
the light of mid-day as possible.
compressive force.
7. Apparatus
3.1.4 potentially suitable field area—the portions of a site
that remain after observing limiting surface features such as 7.1 Tools typically used are a soil knife or a flat blade screw
driver, tape measure, pencil and paper, Munsell soil color
charts (5), water bottle, wash rag, and a sack to carry samples
if required. A pocket penetrometer may also be useful. When
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the presence of carbonate may be significant in soils, dilute
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on hydrochloric acid (10 % HCl) should be used.
the ASTM website.
7.2 A backhoe will facilitate excavation of the test pits for
The last approved version of this historical standard is referenced on
www.astm.org. examination. However, if the site is inaccessible or funds are
D5921 − 96 (2010)
limited, one may excavate by hand with a shovel. Depending 9.6.1 Measure the depth of the layer from the soil-air
on site conditions, power driven or hand held soil augers may interface. Positive numerical values indicate increasing depth.
also be suitable. Tube samplers allow description of soil 9.6.2 Describe color of soil with soil in the moist state. Use
morphologic features providing the size of the feature does not Munsellcolorchart (5)designationforhue,value,andchroma.
exceed the diameter of the core.Augers generally destroy such Include the color name. Indicate lighting conditions, if other
morphologic features as soil structure and porosity.The advan- than direct sunlight.
tage of augers and tube samplers is that they are generally 9.6.3 Estimate the volumetric percentage of rock fragments
faster and less expensive than excavated pits. Their disadvan- (see Fig. 1).
tage is that they sample a smaller area of soil, preventing 9.6.4 Describe size, shape, and percentage of rock frag-
characterization of lateral changes in horizon boundaries and ments (see Table 2).
description of larger-scale morphologic features. Use of probes 9.6.5 Describe the texture of the<2mm fraction of the
or augers as an alternative to excavated pits requires a higher layer using the flow chart in Fig. 2 as a guide. See Table 3 for
degree of experience and knowledge about soils in an area. abbreviations. For sandy soils, (that is, less than 20 % clay and
greaterthan50 %sandbyweight),afieldsieveanalysisallows
7.3 For preliminary examination of a site, one may probe
more precise texture classification using Table 4.
vertically into the soil to get a feel for the presence and depth
9.6.6 Note the presence or absence of mottles. Describe
to a compacted layer, or a water table.Tools that might be used
color (5); proportion (see Fig. 1); and abundance, size, and
include a digging bar, tile probe, post hole digger, or hand soil
contrast of mottles (see Table).
auger.
9.6.7 Describe soil structure by grade using Table 6 and
shape and size using Fig. 3 and Fig. 4.
8. Location of Sampling Points
9.6.8 Describesoil-ruptureresistanceusingcriteriainTable.
8.1 Test pits or other subsurface sampling points should be
9.6.9 If cementation is suspected, bring an intact soil clod
locatedinthepotentiallysuitablefieldareaasdeterminedusing
from the site for further testing.Air dry the clod. Submerge the
Practice D5879, taking into consideration proximity of source
clod in water for at least 1 h. Perform the same tests for rupture
of waste water and down slope of source, if possible. Locating
resistance as shown in Table 7. The sample is cemented if it
down slope gives most flexibility in system design by allowing
meets the very hard classification test. Describe the degree of
either gravity flow or pressure distribution. A preliminary
cementation using classes given in Table 7.
sizing of the field should be performed in accordance with
9.6.10 Measure soil penetration resistance with a pocket
Practice D5925 to determine placement of the sample points.
penetrometer and describe the condition of the soil following
Generally,samplepointsshouldbelocatedondiagonalcorners
the criteria in Table 8.
of the preliminary drainfield area so as to avoid disturbing the
9.6.11 Describe abundance, size, and distribution of roots
soil within the recommended field area. Depending on site
using modifier criteria given in Table 9 and Fig. 5.
conditions, additional sample points may be required to iden-
9.6.12 Describe abundance, size, distribution and type of
tify a recommended field area.
soil pores using criteria in Table 10 and Fig. 5.
9.6.13 If presence or absence of carbonates is a diagnostic
9. Procedure
soil property, use hydrochloric acid to determine depth to free
9.1 Orient the excavation to expose the vertical face to the
carbonate. Describe effervescence as follows: (0) very slightly
best light.
effervescent (few bubbles), (1) slightly effervescent (bubbles
9.2 Excavate the test pit to a depth sufficient to satisfy the readily),(2)stronglyeffervescent(bubblesformlowfoam),(3)
vertical separation required by the governing agency. If the violently effervescent (thick foam forms quickly), and (4)
limiting depth is too shallow to meet the vertical separation noneffervescent.
requirement, it may be desirable to excavate deeper to deter- 9.6.14 Describe layer boundaries according to its distinct-
mine if the layer is underlain by permeable material. ness and topography as shown in Table 11.
9.6.15 Estimatemoistureconditionsofthesoilasdry,moist,
9.3 Enterthetestpitusingallapplicablesafetyrequirements
or wet using the guidelines in Table 12. Measure the depth to
andexaminethesoillayers,orhorizons.Selectarepresentative
zon
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