Education

B.S. Petroleum Engineering, University of Tulsa
M.S. Civil Engineering, Oklahoma State University

Short Courses
Pressure Transient Testing Design & Analysis, Midland, TX
Real Estate Appraisal and Leasing, US Army Corps of Engineers
Real Estate Appraisal Principals & Basic Valuation Procedures, (AIREA)
Part 1 Capitalization (AIREA)
Part II & III Capitalization (AIREA)
Litigation Valuation (AIREA)
Case Studies (AIREA)
Gas Reservoir Engineering, Houston TX
Economic Evaluation & Investment Decision Methods; Colorado School of Mines,
Environmental Engineering & Ecology, The US Civil Service Commission, Dallas Region

Work History
Tulsa District Corps of Engineers, Tulsa, Ok, serving in Petroleum and Civil Engineering positions.
Employed by William H. Pine, Okmulgee, OK, an independent oil and gas producer, with duties of well
completion, well work-over, well production and oil and gas reserve estimating. Employed by AMACO in
a Petroleum Engineering position with duties involving oil and gas lease operations.

Appraisal & Review Appraisal Experience
My duties as a Petroleum Engineer with the Corps of Engineers were to appraise producing and
non-producing mineral rights interests that the Government was to acquire. Also, my duties included
preparation of specifications for well plugging. All mineral rights appraisals were of working and
non-working interests in oil, gas, coal, sand and gravel and other mineral leases and mining claims, as
well as royalties, overriding royalties, and nonparticipating interests. The appraisals were also inclusive
of fee ownership in the mineral rights. Most of my appraisals and review appraisal work has been for
the Tulsa District Corps of Engineers. However, I have prepared appraisals and appraisal reviews for
other Corps of Engineers Districts. In addition I have prepared appraisals and appraisal reviews for
other Federal Agencies under Interagency Agreements with the Tulsa District Corps of Engineers.
These Agencies have included; the Bureau of Reclamation, National Park Service, US soil Conservation
Service, Department of Commerce, Department of Justice and the Department of Energy.

The appraisals and appraisal review reports that I have prepared have concerned mineral rights
properties located in the following states; Arkansas, Arizona, California, Colorado, Kansas, Missouri,
Mississippi, Nevada, New Mexico, Ohio, Oklahoma, Texas, Washington and Wyoming. I have also
appraised a Marine Terminal and five pipelines associated with the Strategic Petroleum Reserve
facilities in Louisiana and Texas for the DOE, New Orleans, Louisiana.

Subsequent to retirement, I have continued to prepare mineral appraisals and appraisal reviews for
various Federal Agencies. In addition to Government contract work, I have also prepared appraisals and
appraisal reviews for private interests. All of my appraisal and appraisal review work have involved
mineral interests in the United States. However, I did prepare an appraisal that concerned a mineral
interest in Hungary.

Expert Witness
I have testified as an expert witness in Federal Court on numerous occasions for the US Army Corps of
Engineers, Bureau of Reclamation and Bureau of Indian Affairs.

Professional Membership
Certified Mineral Appraiser, American Institute of Mineral Appraisers (AIMA)

Papers
I have prepared papers concerning appraisal of mineral rights for two Corps of Engineers Real Estate
National Seminars, the Tulsa Chapter of the American Society of Appraisers, the National Association of
Government Appraisers, the Department of Justice December 1993 Eminent Domain Seminar at San
Antonio, TX, the Federal Land Bank of Wichita and the Society of Mining Engineers 2005 Annual Meeting,
Salt Lake City, Utah.

Other Experience
I was a member of the International Valuation Standards Committee Task Force for the Extractive
Industries.
Donald E. Warnken, PE, CMA
Congdon & Company has been fortunate to contract the review and consulting services of Mr. Donald Warnken, PE,
CMA.  His knowledge and experience in mineral appraisal has proven to be of great value to Congdon & Company's
confidence in the credibility of mineral rights valuations.
Phone: 607-757-0435
Fax: 607-757-0742
rdcongdon@stny.rr.com