Purkeypile Consulting, LLC  


Richard Dee Purkeypile, P.E.

Dam Safety Engineering & Water Resources Consulting

Phone: (512) 971-2264

email: dtpurkeypile@cox.net or



Purkeypile Consulting, LLC was formed in July of 2010 for the purpose of providing professional engineering services to owners of dams in Texas. Richard Dee Purkeypile, P.E. is the president and sole operator of Purkeypile Consulting. Mr. Purkeypile also acts as a dam safety engineering consultant to engineering firms that do not have an in-house specialist with experience in the assessment, analysis, design, repair and construction of dams.

Eureka Springs, AR

Black Bass Dam

Mr. Purkeypile has 27 years of experience dealing specifically with engineering issues related to dams.  Professional services consist of:  

1.                           On-Site Assessments and Dam Safety Inspections

2.                           Operation & Maintenance Plans

3.                           Hydrologic Analysis of the contributing drainage area of dams.

4.                           Hydraulic Analysis of the existing or proposed spillways for dams.

5.                           Static Stability Analysis of earthen or concrete dams.

6.                           Breach Analysis (dynamic or simplified).

7.                           Emergency Action Plan development.

8.                           Plans & Specifications for new construction or rehabilitation of existing dams.

9.                           Bid Phase and Construction Inspection services for new or existing dams.

10.                       Water Rights assistance.


Mr. Purkeypile has 15 years of experience with the Texas Dam Safety Program and functioned as a senior engineer with that agency prior to entering private engineering consultation. During his tenure with the Dam Safety Program he performed over 400 hundred dam safety inspections, performed over 200 hydrologic and hydraulic (H&H) analyses and performed 60 breach analyses of dams.


Mr. Purkeypile has worked in the private sector for 12 years and has inspected over 500 dams and has performed H&H and breach analyses for over 150 dams.


The engineering analysis of a dam often leads to the improvement of an existing dam or the construction of a new dam. Purkeypile Consulting has developed plans and specifications and has provided construction observation for 30 dams and currently has five dams under various stages of construction.


The following is a description of a typical dam safety engineering project. The specific project may entail some or all of the steps noted below:


Data Collection: Data is collected from the dam owner and the state or federal agency that regulates the dam. The data may include: engineering studies, plans & specifications of the original construction or any modifications, geotechnical reports, computer models, paper copies of reports, regulatory correspondence, maps, photography, etc. All data is copied and provided to the dam owner for future reference.


On-Site Assessment: A site visit is performed which includes a detailed physical inspection of the surface of the dam and all of its appurtenances. The dam may consist of an earthen embankment with low flow outlets, principal spillways and emergency spillways and spillway diversion berms. Other areas may also be inspected such as gated spillways, raw water intake facilities for water treatment plants as well as irrigation and possibly recreations facilities.


An inspection report is generated that provides observations of deficiencies and recommendations for the repair and maintenance of the dam.


The on-site assessment also includes a downstream hazard determination. Existing U.S.G.S. topographic maps and the most recent available aerial photography is used to indentify houses, commercial buildings, roadways, railroad embankments and critical infrastructure. A downstream investigation is performed that includes determining the finished floor elevations above the adjacent creek of all habitable structures. A preliminary hazard classification is made. The investigation identifies the surveying needs for future breach analysis needs which will finalize the hazard classification.


Operation and Maintenance Plan: Many states require an O&M plan for regulated dams. They typically include a schedule of regular maintenance items and the course of action needed for repair activities. Normal maintenance personnel are listed as well as emergency responders. Locations are identified for the staging and storage of repair materials. Monitoring activities might include periodic observation and measurement of seepage flow or monitoring concrete crack movement or unstable areas on earthen embankment. An O&M Plan is developed specific to each dam.  


Hydrologic & Hydraulic (H&H) Analysis: The drainage area is determined using USGS topographic maps or, if available, from survey or LIDAR mapping. Soils and land use data are obtained from the USDA Natural Resources Conservation Service (NRCS) which are used to derive runoff curve numbers. The times of concentration are developed using average stream hydraulics. Elevation, area, and capacity data are developed for the impoundment using average end-area calculations. The discharge rating curves for the spillway are determined using various hydraulic computer models, spreadsheets and nomographs. The rating curves are often extended above the top of dam elevation in order to model flow over the dam during a breach analysis.


The H&H analysis can vary from one small basin with one dam to multiple basins with multiple dams in series or laterally contributing to the stream flow.


An engineering report is generated that discusses the hydraulic adequacy of the dam per state regulation. Hydraulically inadequate dams are further studied to determine whether the dam should be raised or the spillway widened or a combination of both. Recommended spillways may include but are not limited to: earthen spillways with grass or high performance turf reinforcement mat as erosion protection, reinforced concrete or other hard armoring such as rock rip rap or articulated concrete block revetment, drop inlet or morning glory spillways, labyrinth weirs, ogee crests, gated spillways, etc.


Breach Analysis and EAP Preparation: Emergency Action Plans require that a breach analysis be performed for the dam. Simplified breach analysis is allowed in some states; however, the preferable method is a detailed dynamic breach routing. The dynamic routing provides better attenuation of breach flow sin the downstream valley. The dam is breached under various scenarios which include: internal erosion during a non-flood event (“Sunny-day breach), a barely overtopping storm event and finally the required test flood event. If the soil parameters are know for an earthen embankments then sediment transport equations are used to derive the time of the breach formation and the final breach geometry. Otherwise, there are standard parameters available from the National Weather Service, Corps of Engineers and the Bureau of Reclamation to determine the time of maximum breach formation and the final geometry of the breach. The breach wave is routed downstream using valley cross section information taken from contour maps or ground surveys. Obstructions and channel constrictions from roadways, railroads or channel geometry are defined. Wide expansive areas that may provide dead storage and attenuation of flood flows are also defined. The breach study area includes the dam and the area downstream of the dam where the breach versus non-breach water surface differential is less than one foot.


An inundation map will be developed for the dam using the most recent available aerial photography with contour overlays. The map will show the design storm breach and the “Sunny Day” breach footprint below the dam and will identify homes that will need to be evacuated during a breach condition. The inundation map will also have depths and velocities of flow over road crossings and at any inundated residences. A breach analysis report will be created for the dam which includes breach wave travel times and peak water surface elevations for downstream residents.


The breach analysis and the inundation map will be included in the EAP which also includes an emergency notification flow chart that has the contact information and chain of command for the emergency responders for a dam safety emergency. The names addresses and phone numbers of downstream residents are provided on an emergency call list. Emergency procedures are enumerated and broadcast emergency messages are listed. Emergency assembly locations and evacuation routes are shown on the inundation map.


Plans, Specifications, Bid & Construction Inspection Services: The H&H analysis may require that existing dams be modified to safely pass the state’s required test flood. Existing dams may also experience damage as a result of large storm events. The State Of Texas requires that plans and specifications be developed by a qualified engineer with experience in the design, repair and construction of dams. Purkeypile Consulting can develop plans and technical specifications that follow the accepted engineering practices and design requirements of Texas. Additionally, services are provided for estimation of materials quantities, bid phase services, and construction inspection services to insure that the contractor performs as directed by the plans and specifications. Theses services are also provided for the site assessment and design of new dams.


Computer Programs: The following is a list of computer programs that are typically used in a dam safety engineering project.


            U.S. Corps of Engineers: HMR-51, HMR-52, HEC-1, HEC-HMS, HEC-2, HEC-RAS,


National Weather Service: NWS-DAMBRK, NWS-BREACH, NWS-FLDWAV

Natural Resources Conservation Service: DAMS2, SITES, TR-55, WSP2


Technical References: The following technical references are used and are considered to be accepted engineering practice.


U.S. Corps of Engineers: Engineering Manuals, HEC Hydraulic Reference Manuals

USDA NRCS: National Engineering Handbook, TR-55, TR-60, TR-66, Technical Notes, Soil Surveys

Bureau of Reclamation: design of Small dams, SEED Manual

Federal Highways Administration: FHWA hydraulics reference library which includes Hydraulic Design Series, Hydraulic Engineering Circulars, Hydraulic Reports

National Oceanic and Atmospheric Administration (NOAA): Precipitation data found in Technical Papers, TP-40, TP-35, TP-49

National Climatic Data Center (NCDC): Archived weather data of the United States.

U.S. Geologic Service (USGS): Scientific Investigations Reports, stream gage data, topographic maps.