HomeMy WebLinkAbout1996-04-10; Municipal Water District; 0410.03; San Marcos Creek Dam.. Z 0 F
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4B# 0410-03 TITLE:
MTG. 04/10/96
DEPT. CMWD
- SAN MARCOS CREEK DAM
DEPT. HD.
CITY ATPI.
CITY MGR.
This is a discussion item only. No recommendation is requested at this time.
ITEM EXPLANATION:
The District Engineer will make a presentation concerning the possibility of building a dam
on San Marcos Creek.
PRELIMINARY SITE EVALUATION
FOR CONSTRUCTION OF
SAN MARCOS CREEK DAM
DAM CHARACTERISTICS
HEIGHT: 175 feet
CREST LENGTH: 400 feet
BASE WIDTH: 550 feet
EARTH VOLUME:
ACCESS ROAD:
277,000 CY - Reinforced Concrete Face With Rockfill
Piragua Street - Vista Bonita
STORAGE CAPACITY: 1,640 ACRE-FEET
APPURTENANT FACILITIES
PUMP STATION:
MAHR RESERVOIR: 600-feet elevation
PIPELINE: 7,000 feet of 12-inch
PRESSURE FILTERS
CHLORINATION SYSTEM
700 gpm at 500-feet TDH using 120 HP motors
Chemical Water Condition Reference Standards TDS 536 mg/L to 4OOO mg/L Max 750 to 1500 mg/L
PH 7.70 6.5 to 8.5
Fecal Coliform Bacteria 1,600 per 100 ml 1 per 100 ml
NITRATE as NO, 10.5 mg/L (C00-15mg/L) 10 mgll (Max DO- 5mg/L)
PHOSPHATE 1.64 mg/L 1.95 mg/L
(High levels of nutrients will encourage the growth of algae, cause for low oxygen levels) Some heavy metals were found in high concentrations.
CONSIDERATION FOR UVE STREAM DISCHARGE FROM MEADOWLARK WRP TO
IMPROVE WATER QUAUTY POSSIBLE USE OF WATER FOR IRRIGATION
TRIBUTARY FLOW RATE
No stream gage data available October, 1991 measurement at <0.6 cfs
100-YEAR STORM: 12,000 cfs
500-YEAR STORM: 19,000 cfs
!
OTHER CONSIDERATIONS
1. PROJECT COST $9,OOO,OOO
2. ASSUMED WATER MELD - lo00 ACRE-FEET PER YEAR. (WATER USED ONLY
FOR IRRIGATION).
3. WATER QUALITY MAY LIMIT THE USE OF THIS WATER SOURCE
4. TRIBUTARY FLOW IS LOW EXCEPT DURING STORM EVENTS
5. ALGAE GROWW ANTICIPATED RESULTING IN TOXICITY AND VISUAL
AESTHETIC CONCERNS
6. COULD CONSIDER IMPROVING WATER QUAUTYAND FLOW RATE BY HAVlNG
UVE STREAM DISCHARGE FROM MEADOWLARK WRP & AERATION
7. DIRECT IMPACT TO SAN MARCOS CREEK CONSERVED HABITAT
8. CONSTRUCTION IMPACTS TO LOCAL COMMUNITY
COULD CONSIDER REVIEWING PROJECT IN MORE DETAIL IN 1996 MASTER PLAN
PROCESS