Appendix G: Engineering Memo Defining Sewage Production
GMS, INC.
CONSULTING ENGINEERS
611 NORTH WEBER, SUITE 300
COLORADO SPRINGS, COLORADO 80903-1074
TELEPHONE (719)475-2935
TELEFAX (719) 475-2938
EDWARD D. MEYER, P.E.
ROGER J. SAMS, P.E.
GREGORY R. WORDEN, P.E.
KEN L. WHITE, P.L.S.
DAVID R. FRISCH, P.L.S.
THOMAS A. McCLERNAN, P.E.
MEMORANDUM
DATE: August 17, 2006
TO: Mr. Rich Muzzy, Environmental Coordinator, Pikes Peak Area Council of Governments
FROM: Roger J. Sams, P.E., GMS, Inc.
RE: Security Sanitation District, Single Family Equivalent (SFE) Unit Wastewater Volume Contribution
During the presentation of the proposed Riverbend Subdivision wastewater pump station at the Site Application Review Committee (SARC), it was requested that there be some verification provided as to the SFE unit volume contribution utilized in the Site Location Approval Application. GMS, INC. and the Security Sanitation District provided the SFE contribution of 198 gallons per day to the applicant for use in their documents.
This unit contribution has been a reasonable design criteria utilized by the District for several years. It was originally developed several years ago in the evaluation of user charges that included a detailed evaluation of unit contributions from all classes of users in the District. The basic methodology in developing this value was as follows:
- Metered water use records were evaluated for a random sampling of single family detached residential users in the District.
- The in-house use only was evaluated by considering the water supply delivered to the customer during the months of December, January and February.
- Based on that analysis, it was found that the average contribution over the random sampling (approximately 100 customers) was 5,719 gallons per billing period, approximately one month.
- It has been accepted that approximately 95% of in-house water use is returned to the wastewater system. This results in approximately 5,433 gallons per month or 178.6 gallons per day (gpd) being returned to the wastewater system.
- Based on the observed ratio of maximum month flow volume or rate to annual average flow volume or rate, the average annual unit volume is increased by 10.5% to 197.4 gpd. This has been rounded up to 198 gallons per day per SFE.
We trust that you will find this statement as to the origin of the SFE unit contribution value sufficient for your records. We will encourage the applicant to include this memorandum with their final submittal to the Colorado Department of Public Health and Environment, Water Quality Control Division, in support of the unit flow contribution used in the design of the pump station. Should you have any questions or desire additional information, please contact us at your convenience.
cc:
- Mr. Roy Heald, Manager, Security Sanitation District
- Mr. Jay Adriansen, Superintendent, Security Sanitation District
- Mr. Chuck Ritter, P.E., Nolte Associates, Inc.