Hydraulic Loading
Based Upon Soil Morphology in Upper 50 cm of Soil
Loading Rates
(gallons per linear foot per day)
Structure
Texture
Shape
Strong
Gravely coarse sand
Coarse sand
Sand
Fine sand
Very fine sand
Loamy coarse sand
Loamy sand
Loamy fine sand
Loamy very fine sand
Coarse sandy loam
Sandy loam
Fine sandy loam
Very fine sandy loam
Loam
Silt loam
Sandy clay loam
Clay loam
Silty clay loam
Sandy clay
Silty clay
Clay
Platy
Moderate
Weak
Pr / Blk / Gr
Strong
Moderate
Not Suitable
.33
Weak
Structureless
Single
Massive
Grain
.33 - .25
.33
.33 - .25
.33 - .25
.33
.33 - .25
.33 - .25
< .25
.33
.33 - .25
.33 - .25
< .25
< .25
< .25
Not
Suitable
Not Suitable
Not
Suitable
< .25
Not
Suitable
Not Suitable refers to textural and structural combinations typically not conductive to
water movement and / or gas exchange, compromising suitability for wastewater
treatment and disposal. Maybe provisionally suitable considering various conditions,
including slope, texture, consistence, and depth to limitation. In situ conductivity tests
maybe indicated based on evaluator’s regional experience with the soil type.
Notes:
 Hydraulic loading rate should be based on most limiting condition within 50 cm.
 If the answer to the “Suitable Sewage Disposal System” was “None,” mark “No
suitable system”.
 Some of the texture/structure combinations listed above are generally not observed in
nature (e.g., a single-grained clay).
Kathleen/Joe/Hydraulic Loading
Modified Pennsylvania On-Lot Sewage Disposal System Matrix
Slope %
Depth to Limiting Zone (cm) 1
0 – 25
26 – 50
51 – 121
122 – 152
153 +
0–8
None
Spray
Mound or
Drip
At-Grade
In-Ground
Bed
8 – 12
None
Spray
Mound or
Drip
At-Grade
In-Ground
Trench
12 – 15
None
None
Mound*
or Drip
Drip
In-Ground
Trench
15 – 25
None
None
Drip
Drip
In-Ground
Trench
25 +
None
None
None
None
None
* Limited Application
1 Limiting
Zone is defined as:
i.
A seasonal highwater table observed by the presence of depleted redox
features of a chroma of 2 or less and a value or 4 or more.
ii.
Rock with open joints, fracture or solution channels or masses of loose
coarse fragments with insufficient fine earth (soil) to fill the voids between
the fragments
iii.
Rock formation, other stratum or soil condition which is so slowly
permeable that it effectively limits downward passage of effluent
(corresponds to root limiting conditions)
Kathleen/Joe/Hydraulic Loading
Dwelling with Basement: Adapted from NSH Table 603-17
Degree of Limitations
--------------------------------------------Slight
Moderate
Severe
------------------------None
---Rare or
Common
Factors Affecting Use
1. Flooding frequency
2. Slope (pct)
<8
8 - 15
>15
3. Depth to seasonally
high water table (cm)
>180
75-180
<75
4. Depth to bedrock (cm)
>100
50-100
<50
Local Roads and Streets: Adapted from NSH Table 620-17 and 603-19
1. Flooding frequency
Degree of Limitations
-------------------------------------------Slight
Moderate
Severe
-----------------------None
Rare
Common
2. Slope (pct)
<8
8 - 15
>15
3. Depth to seasonally
high water table (cm)
>75
75-30
<30
4. Depth to bedrock (cm)
>50
<50
----
5a. Frost action (PD-VPD)
Fragmental
Sandy
All others
Sandy-skeletal
5b. Frost action (SWED-SWPD)
Fragmental
Sandy
Sandy-skeletal
Coarse-loamy Coarse-silty
Fine-loamy
Fine-silty
Loamy-skeletal
Clayey
Clayey-skeletal
Factors Affecting Use
Kathleen/Joe/Hydraulic Loading
2001 National Collegiate Soil Judging Contest
For the 2001 National Collegiate Soil Judging Contest, a modification to the soil
interpretations for on-lot sewage disposal is being presented. Historically, the
interpretations have utilized Natural Resources Conservation Service (NRCS) criteria for
septic tanks, dwellings with basements, and roads and streets. For this year’s contest, the
Pennsylvania criteria for on-lot sewage disposal are being substituted for the NRCS
interpretations dealing with on-lot sewage disposal (septic tanks). This approach will
introduce the students to “real world” criteria for on-lot sewage disposal in Pennsylvania.
Throughout the nation, technologies for on-lot sewage disposal are becoming more
sophisticated. In addition, many states require that a soil scientist or a soil classifier
perform the site evaluation. For these reasons, this change in the interpretations is being
introduced as a learning experience for the student.
On-lot sewage disposal in Pennsylvania has been regulated by state regulations since
1968. A certification program was introduced by the Pennsylvania Department of
Environmental Protection (PADEP) in 1974. Individuals are certified to perform site
evaluations and permitting of on-lot sewage disposal systems. This individual, called a
Sewage Enforcement Officer (SEO), is certified by a state licensing board. There is no
formal educational requirement for an individual to be certified as a SEO. However, the
state has recently recognized the need for soil scientists to evaluate certain technologies.
Presently in Pennsylvania, if individual drip irrigation is proposed, a soil scientist must
perform the site evaluation and assessment of hydraulic loading.
The Pennsylvania standard for on-lot sewage disposal requires a four foot renovative
thickness beneath a sewage disposal system. This renovation zone must be free of any
limiting zone. The state has identified three types of limiting zones. Those are:
1.
A seasonal high water table by direct observation or by the presence of soil
mottling (redox depletion features).
2.
Rock with open joints, fractures, solution channels or masses of loose coarse
fragments with insufficient fine earth to fill the voids between the fragments
Kathleen/Joe/Hydraulic Loading
3.
Rock formation or other stratum or soil condition which is slowly permeable
that it will effectively limits the downward passage of effluent
If any of these conditions exist less than 10 inches (25 cm) from the ground surface, there
are currently no systems permissible in Pennsylvania. If this condition exists between 1020 inches (25-50 cm) to the ground surface, individual spray irrigation is feasible. This
system requires a high degree of treatment with disinfection prior to surface application
by spray irrigation. If the limiting zone is encountered between the depths of 20-48
inches (50-120 cm) from the ground surface, an elevated sand mound or drip irrigation is
feasible. If the limitation is between 48-60 inches (120-150 cm) from the ground surface,
an at-grade system is feasible. If the limitation exists 60 inches (150 cm) or greater from
the ground surface, then standard stone and pipe technology utilizing an in-ground trench
or bed system is feasible.
The 2001 National Contest will introduce the student to the Pennsylvania requirements
for on-lot sewage disposal. The student, utilizing the Modified Pennsylvania On-Lot
Sewage Disposal System Matrix chart, will determine a specific system feasible for the
site. This will require the student to accurately determine the slope and depth to a limiting
zone. In addition, the student will determine the hydraulic loading utilized for individual
drip irrigation in Pennsylvania. This determination will be based upon the structure and
texture of the first 20 inches (50 cm) in a test pit. A second chart has been provided for
you entitled hydraulic loading based upon soil morphology. This chart shall require the
student to accurately determine the texture and structure in the first 20 inches (50 cm) of
the profile. The most limiting texture or structure in the first 20 inches (50 cm) of the
profile shall dictate the hydraulic loading for the site. Note that this determination should
only be made if there is no limiting zone in the upper 50 cm. Otherwise, mark “No
suitable system.”
In summary, the same general parameters used in prior contests to assess the limitation
for on-lot sewage disposal shall be utilized for this contest. However, the student will be
introduced to Pennsylvania requirements, which is utilized daily by soil scientists to
assess the suitability for on-lot sewage disposal. The site with severe limitations utilizing
Kathleen/Joe/Hydraulic Loading
the NRCS method still may be suitable for on-lot sewage disposal based upon the
requirements utilized in Pennsylvania.
Joe/2001 soil judging modifications
Kathleen/Joe/Hydraulic Loading