Letters to the Editor

Send your letters to shelly@profsurv.com

Defining Water per Acre-Foot

Dear Editor,

I really enjoy reading the articles in Professional Surveyor Magazine. It helps keep me informed on the new surveying technology. I noticed two errors in one of the articles in the April 2013 issue, “Low-tech Field? Think Again,” which discussed using mobile mapping technology to determine plant density. The errors did not involve the surveying technology and methods discussed, but rather, the term “acre-foot” was given and used incorrectly.  By definition, an acre-foot of water is a volume equal to one foot of water covering a surface area of one acre (i.e. 1 acre-foot = 43,560 cubic feet = 325,851 gallons ... always).

The first error is in the last sentence of the last paragraph of the section titled Mobile Mapping for Research. The author wrote, “Defining variables specific to this property was critical to calculating the volume of water per acre-foot.”  Actually, by definition, the volume of water per acre-foot has nothing to do with the variables of a specific property. That sentence would have been correct if it had been written something like this, “Defining variables specific to this property was critical to calculating the volume of water needed per acre.” The volume of water needed would be the monthly or annual irrigation requirement of the on-site vegetation. It could be given as a number of gallons per acre per month or per year; or it could be given as the number of gallons per month or year for a specific area such as 1.14 acres.

The second error is in the last sentence of the third paragraph in the section titled Continuous Improvement.  The author wrote, “The higher density HOA needs 1.09 gallons per acre-foot (1 cubic foot of water spread across 1 acre), whereas a lower density HOA needs only 0.19 gallons per acre-foot.” There are two errors here. First, the definition of 1 acre-foot should read (1 foot of water covering 1 acre). (Note: This definition is not necessary here because of the next comment.) Secondly, the references of 1.09 gallons per acre-foot and 0.19 gallons per acre-foot are incorrect. These numbers should be shown as “1.09 feet of water” and “0.19 feet of water” in order for the volumes in the next paragraph to be calculated correctly, i.e., 1.09 feet x 43,560 sq. ft./acre x 7.48 gal/cubic foot = 355,179 gallons and 0.19 feet x 43,560 sq ft/acre x 7.48 gal/cubic foot = 60,368 gallons per acre. I would rewrite the sentence as follows: “The higher density HOA needs 1.09 feet of water per acre (per year) whereas a lower density HOA needs only 0.19 feet of water per acre (per year).”

Again I would like to say that I enjoy reading your magazine.

Joe Sahlfeld, PE, PLS (retired)

The Value of Opinion

To the editors,

I am writing this to comment on the article, “The Surveyor as an Expert Witness,” in the March 2013 issue of Professional Surveyor Magazine. Over the years I have read other articles on this subject and got upset enough to formulate a few comments.

The article mentions the surveyor’s “opinion” on certain points and he (or she) should give these to the attorney. The surveyor’s “opinion” on certain subjects has no value. The “opinion” on these subjects is what they are in court to decide. It is the surveyor’s job to make a survey according to the written legal description provided.

In these articles, the surveyor is generally supposed to tell the attorney what is right or wrong because he (or she) usually has no knowledge of case law or rules of evidence which govern what goes on in a court of law. Guess whose job it is to present the case to the court.

I sometimes think the worst thing books or articles on surveying do is to give an explanation of “Adverse Possession.” This is none of the surveyor’s business.  This is what they are in court to decide. It is the business of the court.

After reading the article and thinking it over I came to the conclusion that it was a description of a consultant. And guess what—it was written by a consultant—which is okay but not the job of the surveyor as “Expert Witness.”

I was educated as an engineer but fell into surveying and enjoyed it. I regarded myself as one of the few engineers who understood surveyors.  In fact when [an] administrative assistant asked me what a “scrivener’s error” was I was glad to explain since I have probably made a couple. I am a retired PLS and PE.

Joseph F. Dickrell
Naperville, Illinois

Mr. Dickrell:

PSM has shared your letter with me regarding the article I wrote. I agree with your statement that surveyors should not give opinions on the applications of purely legal doctrines such as adverse possession. I share your belief that a surveyor is not qualified to give an opinion on adverse possession. The surveyor lacks the knowledge, training, and education in these areas. I believe a surveyor should limit their opinion to the location of the deed or record boundary. As the courts often quote: “Where the [record] boundary is located is a question of fact, what is the boundary [e.g., possession line] is a question of law.”

I will close with one point that should be made in regard to the surveyor expressing an opinion at trial. There is no question that the surveyor’s opinion in regard to the location of a boundary is not only sought by the court but it is specifically allowed to be stated. Rule 702 of the Federal Rules of Evidence (and similar state rules of evidence) states:
Rule 702. Testimony by Expert Witnesses: A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.

Thank you for taking the time to write. It has always been my pleasure to get feedback generated by my articles. The time you took to communicate your thoughts is appreciated.

Knud E. Hermansen

Fees Freely Quoted Then and Now


I have enjoyed your magazine for quite some time.  Your articles are always timely and interesting.

As a Florida professional surveyor and mapper, I find Dr. Joe Knetsch’s article on the Initial Point of Florida’s GLO Survey to be quite typical of his work—simply terrific.  It is hard to imagine the amount of research in dark, dingy places to assemble so many pertinent facts.

I also find it immensely interesting (amusing even) that, way-back-when, commissioner Thomas H. Carter felt no shame in quoting a surveyor’s fee, most likely without the knowledge or permission of any surveyor. Apparently it was a problem then, with little changing to present day.

Thanks for the use of the soap box.  Now alighting.

William D. Barker, PLS
Tulsa, Oklahoma


May 2013: The cover shows Murray Roddis at an IndyCar race in Loudon, New Hampshire, August, 2011.

May 2013: In “Where Theory Meets Practice,” the conversion procedure on pages 29 and 30 should be a total of five steps, with steps 1-3 on page 29 and 4-5 at the top of page 30.

May 2013: The name of Virginia governor Bob McDonnell was spelled incorrectly in “Managing Federal Lands Data.”

» Back to our June 2013 Issue

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