Frequently Asked Questions
- Question 1: Is Region 5 Model only for EPA Region 5 states?
- Question 2: What are the differences between STEPL and Region 5 Model?
- Question 3: My ‘Total Load’ worksheet has ‘#VALUE!’ in result cells. What went wrong?
- Question 4: The septic system failure rate seems low, are there other alternative data?
- Question 5: How can I add my own BMPs to STEPL’s BMP list?
- Question 6: Where can I find the definitions of BMPs used in the STEPL and Region 5 Model?
- Question 7: Can you help me use the BMP Calculator?
- Question 8: What are other models that can be used for load reduction calculations?
- Question 14: Can STEPL be used to model bacteria?
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Question 1: Is Region 5 Model only for EPA Region 5 states?
No, Region 5 Model can be used for other states. The model got its
name because it was originally developed in Indiana Department of
Environmental Management based on Michigan Department of Environmental
Quality’s 319 watershed training manual. Both
Question 2: What are the differences between STEPL and Region 5 Model?
Below are the major differences between the two models:
Region 5 Model
- Calculates load at the source level
- Sources are independent (no relationship between worksheets)
- Users can not specify and update BMPs used in the model
STEPL
- Calculates load for different sources at source and watershed level
- Sources are related in watershed
- Users can specify and update BMP list
- Users can use BMP calculator to estimate combined BMP efficiencies for complex BMP arrangements
- On-line input data server for initial model setup (Caution: Do not substitute the on-line data for real local data!!!)
Question 3: My ‘Total Load’ worksheet has
‘#VALUE!’ in result cells. What went wrong?
First of all make sure that you have selected appropriate State, County and
Weather Station from the lists in the Input Sheet.
Another possibility is that you probably entered some non-numerical characters in the input tables on the ‘Input’ sheet. For example, when you copy and paste ‘Agricultural animals’ data from the tables generated by the ‘STEPL Input Data Server’, you may paste non-numerical characters to the STEPL input sheet if the animal number is indicated with ‘D’ for data withheld to avoid disclosing by US Department of Agriculture.
Question 4: The septic system failure rate seems low, are there other alternative data?
Yes. The failure rate data have very high uncertainty. Users are encouraged to obtain the septic failure rate from their local health departments.
Besides the data from the ‘STEPL Input Data Server’ (National Environmental Service Center formally National Small Flow Clearinghouse, 1992 and 1998), Electric Power Research Institute conducted a state-by-state survey on septic failure rate. Below is the summary:
|
State |
Estimated
system failure rate (in %) |
Failure
definition |
|
|
20 |
Not
given |
|
|
0.5 |
Surfacing,
backup, surface or ground water contamination |
|
|
1-4 |
Surfacing,
backup, surface or ground water contamination |
|
|
1-2 |
Surfacing,
backup, surface or ground water contamination |
|
|
1.7 |
Public
hazard |
|
|
15-35 |
Improper
construction, overflow |
|
|
20 |
Backup,
surface or ground water contamination |
|
|
10-15 |
Surfacing,
nuisance conditions (for installations after 1980) |
|
|
50 |
Not
given |
|
|
1 |
Surfacing,
backup, surface or ground water contamination |
|
|
25 |
Public
health |
|
|
50-70 |
Cesspool,
surfacing, inadequate soil layer, leaking |
|
|
30-50 |
Backup,
surface or ground water contamination |
|
|
40 |
Nonconforming
system, water quality |
|
|
<5 |
Surfacing,
backup |
|
|
20 |
Surfacing |
|
|
4 |
Backup,
surface or ground water contamination |
|
|
15-20 |
Not
given |
|
|
28 |
Backup,
surfacing |
|
|
25-30 |
Backup,
surfacing |
|
|
5-10 |
Backup,
surfacing, discharge off property |
|
|
25 |
Not
given |
|
|
6-7 |
Not
given |
|
|
10-15 |
Surfacing,
surface or ground water contamination |
|
|
0.5 |
Surfacing,
backup, exceeding discharge standards |
|
|
33 |
Public
health hazard |
|
|
60 |
Backup,
surface or ground water contamination |
|
|
0.4 |
Backup,
surfacing, ground water contamination |
Question 5: How can I add my own BMPs to STEPL’s BMP list?
You can add, delete, or edit BMPs in the “BMPList” worksheet, which can be shown (unhidden)
by clicking the STEPL > View/Edit BMP List menu. On ‘BMPlist’ worksheet, follow the steps outlined on
the top-right corner. See more information in section 4.6 of the STEPL
user’s guide.
Question 6: Where can I find the definitions of BMPs
used in the STEPL and Region 5 Model?
You can find BMP descriptions in a Microsoft Word document,
BMPDefinition.doc, under your [Local Drive C or D]:\STEPL folder after you
install STEPL on your PC.
Question 7: Can you help me use the BMP Calculator?
Yes. The STEPL user’s guide has a detailed section (Appendix A) that
describes the procedures and examples of using the BMP Calculator.
Question 8: What are other models that can be used for load reduction
calculations?
STEPL and Region 5 models are two of the simplest models for calculating
pollutant load reductions. There are many other models that can be used to calculate
the load reductions, and these models are described in a document in the
STEPL Web site. You can download the document by clicking on ‘List of
Alternative Load and Load Reduction Model’ from: models$docs.htm.
Question 9: If I don't know exactly where all my BMPs for a particular subwatershed
are located (not knowing if they're in the same fields or even affecting
the same tributary) am I better off calculating them in serial or in
parallel configuration for that subwatershed?
Most non-structural BMPs should be used in
parallel configuration (with the BMP Calculator) if you do not know their
locations and spatial relationship. Some downstream structural BMPs or on stream BMPs may be
in serial connection with the upstream BMPs.
e.g., a sediment settling pond may be in serial to upstream BMPs such as no-till practices. If you do not know the
BMP locations in a watershed, assuming parallel BMP configurations will be
better than assuming serial configurations if most of the BMPs are non-structural (except filter strips) or not
in-stream.
Question 10: Why is the STEPL-calculated sediment loading rate (t/ac/yr)
from my watershed much lower than the erosion rate (> 1 t/ac/yr)
reported for my study area? Can you explain?
The sediment output from a watershed is different from on-site erosion. For
cropland in your calculation, erosion rate may be larger than 1 t/ac/yr;
however, the sediment output from your watershed is much lower. The STEPL
model calculates sediment output using "erosion x sediment delivery
ratio". Your watershed area is pretty large, so it results a low
sediment delivery ratio. To see the sediment delivery ratio in STEPL model,
click on STEPL menu > unhide/hide other STEPL sheets, and navigate to
the ‘Sediment’ worksheet, and then check cell "W9".
Your can modify the sediment delivery ratio based on your local data.
Question 11: Some of the data I'm gathering to input into
the STEPL model is not consistent.
For filter strips, I have some data coming to me as actual acres of
filter strip, and some coming to me as acres affected by the filter strip. What is the best way to deal with these
discrepancies in the model?
The important data that STEPL needs is the acreage affected by a filter
strip. For example, if you have 20 acres of cropland affected by a filter
strip, you can choose "Cropland-filter strip" as the BMP in STEPL
and apply it to the affected area for load reduction calculation. The
actual area of a filter strip is less important than the area it controls
due to the factor that (1) the area of the filter strip is usually
significant smaller than the affected area, and (2) the filter strip is not
a source of non-point source pollution (in STEPL, you may exclude it from
the load calculation or treat it as a type of forest).
Question 12: My general question is whether it is
appropriate to use STEPL to compare the loading effects of changing a
particular site from one land use to another, e.g., agricultural to
commercial. I also wonder how it
applies the USLE to "soil loss" from a parking lot.
For assessment and planning purposes, you can use STEPL to compare effects
of land use changes on pollutant loads (N, P, and sediment). However, STEPL
was created to only give rough estimates on load and load reduction, and it
is not intend for making very precise predictions. For urban land uses,
STEPL does not use USLE. STEPL uses annual runoff volume x pollutant
concentration to estimate pollutant loads, including sediment load.
Question 13:
I used the executable to create the spreadsheet file, made some changes
within the spreadsheet. Now, when I
reopen the file, I receive an error message from EXCEL saying 'not enough
system resources to display completely.' Do you know why?
This is due to a peculiar Excel behavior. Change the Input worksheet zoom level to 100% percent and try. If this is not working, make the hidden sheet visible (using the Hide/Unhide menu under STEPL) and then change the zoom level.
Question 14: Can STEPL be used to model bacteria?
STEPL can not be used to model bacteria. There are other models available to model bacteria. These include models like HSPF, SWAT, and PLOAD.
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