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Sierra Lakes Integrated Flood Control Management Concept
DRAFT SIERRA LAKES PROJECT INTEGRATED FLOOD CONTROL, WATER CONSERVATION, AND STORM WATER QUALITY MANAGEMENT CONCEPT August 1993 Prepared by: John M. Tettemer, President Alan A. Swanson, Vice President, Engineering Harold A. Vance, Consulting Engineer TABLE OF CONTENTS Page EXECUTIVE SUMMARY ........................................... viii A. An Integrated Concept .............. I .......................... viii B. Multiple Benefits ............................................... ix C. Design, Installation, and Maintenance Criteria ......................... ix D. Implementation................................................ x I. INTRODUCTION ............................................. 1 A. Project Location and Description .............................. 1 B. Hydrology, Water Conservation, and Water Quality Issues ........... 1 C. Purpose of Report ......................................... 4 D. Conclusions .............................................. 5 E. Recommendations ......................................... 8 II. BACKGROUND ............................................. 10 A. Soil Investigations ........................................ 10 B. Infiltration Tests ......................................... 10 C. Hydrology .............................................. 12 D. Golf Course Flood Water Storage Basins ....................... 13 E. Flood Routing -Infiltration Study Findings ...................... 13 F. Infiltration Facility Concept ................................. 14 G. Water Quality Considerations ............................... 16 III. FIELD INFILTRATION TEST SETUP ............................ 18 A. Test Pit Location ........................................ 18 08/25/93 -i- TABLE OF CONTENTS Page B. Water Delivery and Metering ............................... 18 C. Steady State Flow Conditions ............................... 19 D. Meter Verification ....................................... 19 E. Test Pit Filling .......................................... 19 F. Test Sequence ........................................... 20 IV. FIELD INFILTRATION TEST PROGRAM ......................... 21 A. Test Programs ........................................... 21 B. Test Program No. 1 ....................................... 21 1. Test Pit Configuration ................................ 21 2. Results of Test Program No. 1 ......................... 22 3. Investigation of Edge Conditions ........................ 22 C. Test Program No. 2 ....................................... 23 1. Test Pit Configuration ................................ 23 2. Results of Test Program No. 2 ......................... 24 D. Evaluation of Test Program Nos. 1 and 2 ...................... 24 1. Selection and Testing of Rapid Sand Filter Material ......... 24 2. Sizing of the Sand Filter .............................. 26 E. Test Program No. 3 ....................................... 27 1. Test Pit Configuration ................................ 27 2. Results of Test Program No. 3 ......................... 28 F. Test Program No. 4 ....................................... 29 08/25/93 -ii- TABLE OF CONTENTS Paye 1. Test Pit Configuration ................................ 29 2. Results of Test Program No. 4 ......................... 30 G. Test Program No. 5 ....................................... 32 1. Test Pit Configuration ................................ 32 2. Results of Test Program No. 5 ......................... 33 H. Test Program No. 6 ....................................... 33 1. Test Pit Configuration ................................ 33 2. Results of Test Program No. 6 ......................... 33 V. DISCUSSION OF TEST PROGRAM RESULTS ..................... 35 A. Evaluation of Laboratory Flow Test Data ...................... 35 and Piezometer Data B. Flownet Analyses ........................................ 37 1. Flownet Construction ................................ 37 2. Flownet Analyses ................................... 38 C. Effective Infiltration Rates ................................. 39 D. Size Relationship of Sand Filter Area to Infiltration Area .......... 40 VI. RECOMMENDED DESIGN PARAMETERS ....................... 41 A. Ratio of Sand Filter Area to Infiltration Area ................... 41 B. Infiltration Rate Curve .................................... 41 1. Sand Filter Maintenance Criteria ....................... 41 2. Recommended Infiltration Rate Curve ................... 41 C. Sand Filter/Gravel Layer Material Specifications ................. 42 08/25/93 -iii- TABLE OF CONTENTS Page 1. Gravel Layer ...................................... 42 2., Sand Filter ........................................ 43 3. Filter Fabric ....................................... 43 D. Safety Factor ........................................... 43 E. Possible Failure Modes and Mitigation ........................ 48 VII. OPERATION AND MAINTENANCE REQUIREMENTS .............. 51 A. Delivery System ......................................... 51 1. Off -Site Flood Flows ................................. 51 2. On -Site Flood Flows ................................. 52 B. Water Quality Facilities ................................... 53 1. Description and Purpose of Proposed Facilities ............. 53 2. Objective of the Operation and Maintenance Program ....... 55 3. Maintenance Philosophy .............................. 56 4. Maintenance Program Elements ........................ 56 5. Interim Operation of the Wetland Facilities ............... 58 6. Preparation of the Wetland Field Operations Manual ........ 62 7. Wetland Monitoring ................................. 64 C. Sand Filter Infiltration Facilities ............................. 64 VIII. RESPONSIBILITY FOR OPERATION, MAINTENANCE . ............. 67 AND MONITORING A. Flood Control and Storm Drain Delivery Systems ................ 67 B. Water Quality Wetlands ................................... 67 08/25/93 -iv- TABLE OF CONTENTS Page 1. From Construction to 2 Years Later ..................... 68 2. After Two Years .................................... 68 C. Sand Filter Infiltration Facilities ............................. 69 IX. ROLE AND RESPONSIBILITY OF THE DEVELOPER ............... 70 AND GOVERNMENT AGENCIES A. Lewis Homes ........................................... 70 B. City of Fontana .......................................... 71 C. San Bernardino County .................................... 72 Transportation/Flood Control District D. Golf Course Owner/Operator ............................... 73 X. LIABILITY ................................................. 74 XI. PHASING OF CONSTRUCTION ................................. 75 XII. FINANCING OF CONSTRUCTION AND OPERATION . .............. 76 MAINTENANCE, MONITORING, AND REPORTING XIII. FIGURES ................................................... 77 Figure 1: Location Map Figure 2: Conceptual Development and Recharge 08/25/93 -v- Basin Location Plan Figure 3: Location Map, RMA Group Percolation Tests Figure 4: Typical Water Quality Wetland Facility Figure 5: Sand Filter/Gravel Layer Infiltration Concept Figure 6: Test Program No. 1, Plan and Section Figure 7: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program No. 1 Figure 8: Infiltration Test Results, Flownet Analysis, Test Program No. 1 Figure 9: Test Program No. 2, Plan and Section 08/25/93 -v- TABLE OF CONTENTS Page Figure 10: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program Page 2: Nos. 1 and 2 Figure 11: Sand Gradation Plots Figure 12: Laboratory Flow Test Results Figure 13: Sample Computation of Sand Filter Size Figure 14: Test Program No. 3, Plan and Section Figure 15: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program Nos. 1, 2, and 3 Figure 16: Test Program Nos. 4A, 4B, 4C, Plan and Section Figure 17: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program Nos. 3, 4A, 413, 4C Figure 18: Silt Migration Data Figure 19: Test Program No. 5, Plan and Section Figure 20: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program Nos. 3 and 5 Figure 21: Test Program No. 6, Plan and Section Figure 22: Infiltration Test Results, Depth vs. Rate of Infiltration, Test Program Nos. 3and 6 Figure 23: Recommended Design Infiltration Rate Curve, Location I Figure 24: Proposed Off -Site and On -Site Drainage Facilities Figure 25: Typical Rapid Sand Filter Testing Locations XIV. PHOTOGRAPHS ............................................. 78 Page 1: Photographs of Flow Meters and Transmission Line Page 2: Test Program No. 1 Page 3: Test Program No. 2 Page 4: Test Program No. 3 Page 5: Test Program No. 4 Page 6: Test Program No. 5 Page 7: Test Program No. 6 08/25/93 -vi- TABLE OF CONTENTS Page XV. APPENDICES (under separate cover) .............................. 79 Appendix A: RMA Infiltration Test Reports 1. Soil Percolation Report for Sierra Lakes, Highland and Sierra Avenues 2. Additional Soils Percolation Testing for Feasibility of Onsite Storm Water Retention, 640 Acre Sierra Lakes Project Appendix B: Hydrologic Feasibility Study Appendix C: Laboratory Test Results 1. Particle Size Analysis 2. Flow Test Data Appendix D: Field Data Records Appendix E: List of Visitors at Test Site Appendix F: Pre -Storm Season Inspection Report Form Appendix G: Wetland Monitoring and Inspection Form LIST OF TABLES Table 1: Summary of Auger Hole Infiltration Tests ...................... 10 Table 2: Comparison of Computed (Laboratory) and ..................... 35 Measured (Piezometers) Loss of Head in Feet through the Sand Filter Table 3: Adjustment Factors to be Applied to Infiltration ................. 39 Rate Design Curve Ordinates for Varying Infiltration Area Widths 08/25/93 -vii- EXECUTIVE SUMMARY A. An Integrated Concept This report presents a conceptual integrated flood control -water conservation - water quality management plan for Sierra Lakes. The plan is conceptual only due to the preliminary nature of the golf course grading plan and the flood water collection systems. The integrated concept itself is practical and valid, soundly based on extensive soil studies and a carefully designed and executed field testing program to develop design criteria for infiltration facilities to be incorporated into the golf course fairways. It has been tested by applying the San Bernardino County Transportation/Flood Control Department (SBCTFCD) multiple -day design storm and routing the resulting hydrographs through the system of golf course basins. It can be concluded that, due to the high infiltration rates exhibited by the porous gravelly soil on the site, the concept can be developed into a viable plan, compatible with the current golf course layout and development plan. Under this concept, off-site and on-site drainage will be collected, temporarily stored in golf course fairways gently graded to form basins, and allowed to infiltrate into the porous alluvial soil. Special infiltration facilities resembling golf course bunkers will be placed along some of the fairways to assure that planned infiltration rates will be maintained over the long term. Special water quality wetlands will remove first -flush storm runoff and urban nuisance flow from the drainage system so these polluted flows never enter the infiltration facilities. The water quality wetlands will remove sediments, minimize silt build-up in the infiltration facilities, reduce 08/25/93 -viii- maintenance requirements, and enhance the quality of water being infiltrated to the aquifer. Under design flood conditions there will be no runoff from the site. Runoff from the extreme southerly end of the site will also be managed through infiltration systems to be incorporated into the development plan. B. Multiple Benefits The traditional drainage approach is to collect off-site and on-site flows, carry them safely through the development in an adequate flood control system, and deliver them to downstream facilities. The concept described herein offers several advantages over the traditional approach. By storing the water and allowing it to infiltrate, downstream flow rates and the cost of downstream flood control works are reduced. At the same time, the water is conserved by recharging the aquifer. Also, due to the water quality wetlands, the quality of water infiltrated is expected to be superior to that typical of runoff in the region. As a result of the pollutant removals in the water quality wetlands and the "zero -runoff' from the site, there will be a virtual "zero -discharge" of pollutants from the site. C. Design, Installation, and Maintenance Criteria The report presents design criteria for the infiltration facilities based on the field infiltration tests. Monitoring, maintenance, and operational criteria and procedures are presented to assure the continued reliable performance of the infiltration facilities, the water quality wetlands, and the flood water collection and conveyance system. The report describes an interim monitoring, maintenance, and operation program for the water quality wetlands which calls for supervision by a wetlands specialist during the plant establishment period, and the preparation of a Field Operations Manual based on the experience gained during this period. 08/25/93 -ix- Safety factors to he incorporated into the design, and mitigation measures for floods greater than the SBCTFCD design flood and other contingencies are provided. D. Implementation The report describes the steps needed to proceed with implementation, including final design of the golf course, flood water collection and conveyance system, water quality wetlands, infiltration facilities, and flood contingency plans. Also described is the need to reach agreement among the agencies and private parties involved on roles and responsibility for implementation, monitoring, maintenance, operation, and reporting on the various system components. The liability attached to each party is described. 08/25/93 -X_ I. INTRODUCTION A. Project Location and Description The Sierra Lakes project is located in the northern portion of the City of Fontana (City) (Figure 1). The project site includes the one square mile bounded on the north by Summit Avenue, on the west by Citrus Avenue, on the east by Sierra Avenue, and on the south by Highland Avenue. Also included in the project area is the 60 -acre parcel bounded on the north by Curtis Avenue, on the west by Catawba Avenue, and by Citrus Avenue on the east. The Sierra Lakes project is being developed by Lewis Homes of California as a planned community consisting of residential and commercial land uses to be constructed around an 18 -hole golf course. The conceptual land use plan and golf course configuration for the one square mile portion of the project are shown on Figure 2. B. Hydrology, Water Conservation, and Water Quality Issues Development of the Sierra Lakes project will require drainage and flood control features to meet City, SBCTFCD, and Federal Flood Insurance standards. Water quality management features or practices will be required to meet City and SBCTFCD requirements under the National Pollutant Discharge Elimination System (NPDES) permit issued by the Santa Ana Regional Water Quality Control Board (SARWQCB). Water conservation is a priority issue in the region and should be incorporated into runoff management plans whenever feasible. 08/25/93 The site is located on a broad, sloping alluvial plain or cone laid down over geologic time by Lytle Creek. Lytle Creek passes about 2 miles north-east of the site and does not affect the site. The plain on which the site is located slopes from north to south. The site is subject to runoff from the local off-site tributary drainage area immediately to the north, and from the site itself. The off-site area consists of 440 acres. The portion of the project area including the golf course consists of a section of land, or 640 acres gross. The southerly edge of this portion of the project is reserved for the future Foothill Freeway and is not part of the development nor included in the hydrology study described herein. Various options are available for managing the runoff affecting the site. One option is to collect the off-site and on-site water, carry it safely through the site, and discharge it at an approved location downstream (south) of the site. The site and its tributary drainage area are included in an existing drainage master plan for San Sevaine Creek. Another option, described herein, is to collect the off-site and on-site water, store it temporarily in golf course fairways graded to form basins, and allow it to infiltrate into the soil. This option is made possible by the unusually high infiltration rates known to exist in the porous soils and gravels of the alluvial cone. If design, maintenance, and operational criteria can be satisfactorily developed and implemented, this option offers the following advantages over the one described above: 08/25/93 -2- a Savings in the cost of the San Sevaine Creek system by reducing its flow requirement; ■ Water conservation, which is a high priority objective within the City and throughout Southern California; and ■ Enhanced groundwater quality; because the water quality management facilities will remove first -flush storm runoff and urban nuisance flow from the drainage system, together with any pollutants that they contain, so they never enter the infiltration facilities. ■ Enhanced surface water quality downstream of the project, because the system produces virtually no runoff, and thereby discharges virtually no pollutants. The feasibility of this approach depends on satisfactory resolution of the following issues: ■ Adequate collection and desilting systems for off-site and on-site - flows; ■ Adequate system of golf course fairway basins and inter -basin conveyances within the site; ■ Adequate infiltration rates within the golf course; ■ Adequate design of infiltration facilities; and ■ Adequate monitoring, maintenance, and operational criteria. C. Purpose of Report This report has been prepared to demonstrate that key issues in the above list are satisfactorily resolved, and the remaining issues can be readily 08/25/93 -3- addressed in the design phase of the Sierra Lakes project. The report accomplishes the following purposes: ■ Presents the hydrologic setting of the Sierra Lakes project. ■ Describes flood flow rates and volumes of runoff to be managed, including multiple -day storms, based on existing land use plans and preliminary drainage collection assumptions. ■ Describes the field testing program carried out to evaluate the infiltration rates of the native soils on the site and of a sand filter - gravel layer infiltration facility that can be incorporated into the golf course design. The testing program included step-by-step testing of: • the native soil; • each component of the infiltration facility; ® the infiltration facility under various levels of siltation; • the infiltration facility with silt -contaminated layers removed and replaced with clean sand; and c the native soil covered with golf course turf. ( 12.0 A(S12.OVfbwunttcnded design criteria for the infiltration facility, including: ( 12.0 She ratio of area of sand filter to gravel layer; ® the infiltration rate curve; and o specifications for the gravel, sand, and filter fabric. ■ Evaluates possible modes of failure and presents reliable mitigation strategies. 08/25/93 -4- ® Presents a water quality management program to remove first -flush storm runoff and urban nuisance flow from the drainage system upstream of the golf course fairways and infiltration facilities, to reduce the buildup of silt in the infiltration facilities, minimize maintenance costs, enhance the quality of the water being infiltrated, and enhance the quality of runoff downstream of the project. ® Develops monitoring, maintenance, and operation requirements for the entire system, including the flood water delivery system, the water quality wetlands, and the infiltration facilities. ■ Recommends the assignment of responsibility for monitoring, maintenance, and operation of each component of the system. ■ Describes the roles and responsibilities of the developer, the golf course operator, and the various public agencies involved. M Describes the liability assumed by the project engineers, the developer, and the public agencies involved © Discusses phasing of construction; and ® Reviews possible financing of construction, monitoring, maintenance, operation, and reporting. D. Conclusions This report is one of a series. Previous studies have suggested the validity of the concept of incorporating golf course storage and infiltration of storm runoff into the flood management plan for the property (Appendix A). The Federal Emergency Management Agency, which administers the National Flood Insurance Program, has indicated it is aware of projects 08/25/93 -5- 1 which have successfully used infiltration as a means of managing flood waters. To determine whether the concept is actually viable for Sierra Lakes, compatible with the development plan and golf course layout, and capable of controlling the design floods, it was necessary to simulate design flood routings for multiple -day storms; confirm the infiltration rates that can be achieved within the golf course; evaluate the performance of the infiltration system under a range of silting conditions; consider water quality management concepts; determine monitoring, maintenance and operational requirements; and consider legal issues, liability, and the roles of the parties involved. The hydrologic analysis, flood routing studies, and field infiltration tests performed for this report demonstrate the feasibility of golf course storage and infiltration, along with suitable water quality management, monitoring, maintenance, and operation procedures, as a flood control concept for Sierra Lakes. The golf course grading, flood delivery system, inter -basin conveyances, and water quality wetland configurations used in this study are conceptual only, and are subject to adjustment and refinement in the design stage. Likewise, the location and configuration of infiltration facilities is subject to revision and adjustment as the golf course design is developed. 08/25/93 -6- Though such details are subject to final design adjustments, the following conclusions are valid, based on the field tests and analyses: ■ The concept of golf course storage and infiltration, combined with water quality management, monitoring, maintenance, and operation, is a feasible concept for meeting flood control requirements for Sierra Lakes. ■ An infiltration facility resembling a golf course sand trap or bunker, with a gravel base layer, can be relied on to provide infiltration rates as a function of head in accordance with the infiltration rate curves presented herein. ■ First -flush storm flows and urban nuisance flows can be reliably removed from the drainage system upstream of the fairways and infiltration facilities and introduced into water quality wetlands for treatment. These flows and any pollutants contained will never enter the infiltration system. This arrangement removes silts from the flow, reduces filter maintenance requirements, and enhances the quality of water to be infiltrated into the aquifer. ■ Even when substantially impaired by siltation, the infiltration facility described herein exhibits high infiltration capacity and can be relied on to perform as predicted by the field tests. ■ Long term success of the infiltration system is dependent on effective maintenance of the water quality wetlands. A responsible, qualified organization or agency should assume responsibility for monitoring, maintaining, and operating them as NPDES facilities in 08/25/93 -7- h criteria to be presented in the Field Operations bed herein. )posed herein has the potential to recharge the asin in the amount of approximately 770 acre-feet per imated value of $308,000. The present worth of this I is $5,000,000. afety factors can be incorporated into the system design to account for floods greater than the design flood and other contingencies. The safety factors are discussed in Section VI.D of this report. ■ The integrated flood control -water conservation -water quality system described herein is a combination of public and private facilities. The roles and responsibilities of all parties involved need to be clearly defined. E. Recommendations ■ Adopt the concept of an integrated flood control -water conservation - water quality management system as described herein for development and implementation in Sierra Lakes. ■ Proceed with planning and design studies to finalize the golf course grading, the off-site and on-site drainage collector systems, the water quality wetlands, and the infiltration facilities as conceptually described herein. ■ Initiate discussions with the City and the SBCTFCD with a view toward entering into an agreement covering the respective roles and 08/25/93 -8- responsibilities of the parties regarding financing, facility maintenance, monitoring, operating, reporting, and liability. ■ Adopt the design criteria, safety factors, and mitigation measures for the golf course basins, inter -basin conveyances, and infiltration facilities set forth in Section VI. ■ Adopt the operation and maintenance criteria set forth in Section VII. ■ Adopt the monitoring program set forth in Section VII. ■ Adopt the water quality wetland interim operation plan described in Section VII, including the preparation of a Field Operations Manual. 08/25/93 -9- II. BACKGROUND During the last several years many engineering studies and field investigations have been conducted to establish the factual basis for proceeding with the current study. Each study and investigation built upon and expanded the knowledge developed from the previous work. Several of the significant background studies which led up to this report are described below. A. Soil Investigations Appendix C contains the results of sieve analyses made on soil samples collected from the site. The samples contain relatively small percentages of fine silt particles passing the No. 100 and No. 200 sieves, and relatively large percentages in the coarse sand sizes represented by sieve No. 16 and smaller and gravel sizes up to three inches. The analyses indicate extremely porous soils which may have infiltration rates high enough to warrant consideration of infiltration as a component of the flood control strategy. B. Infiltration Tests A number of tests have been conducted in the past to determine infiltration rates at several locations on the property. RMA Group, the geotechnical consultant on the project, conducted infiltration tests at auger holes drilled at the locations shown on Figure 3. Details of these investigations are presented in Appendix A. The test results are summarized below: 08/25/93 -10- Table 1 Summary of Auger Hole Infiltration Tests Auger Hole No. Infiltration Rate * (feet per day) P-1 108.1 P-2 48.0 P-3 120.0 P-4 114.3 P-5 77.9 P-6 137.9 P-7 108.1 P-8 90.2 P-9 114.3 P-10 120.0 P-11 114.3 P-12 108.1 P-13 58.8 P-14 126.3 P-15 126.3 P-16 114.3 P-17 131.9 P-18 126.3 P-19 120.0 P-20 36.0 Average 105.1 Calculated based on the "Falling Head Percolation Data" published in RMA Group's report "Soil Percolation Report for Sierra Lakes", November 8, 1989 (see Appendix A) Note: RMA Group's rates are based on the time for the water to drop 1 foot in a 1 -foot deep test hole. 08/25/93 -11- RMA Group also conducted a more detailed infiltration test using an on- site test pit approximately 6 feet deep with a bottom dimension of approximately 20 feet square. The results of this test indicated infiltration rates of up to 30 feet per day. The infiltration rates determined from these tests are significantly greater than rates measured at existing groundwater recharge facilities in Southern California. These high infiltration rates suggest that infiltration can play a significant role in flood management strategy. C. - Hydrology 'eLj To evaluate the feasibility of the infiltration concept a hydrology study was performed to determine the actual flood volumes and rates of flow that must be managed. The study was conducted in accordance with the .ryw ` procedures set out in the SBCTFCD Hydrology Manual, assuming fully U` ° developed watershed conditions. The study considered off-site tributary Vw ,� areas as well as those within the project site which will be directed to the X:,�' golf course recharge basins, for a total of 969 acres. On-site subareas were �. defined which could feasibly be provided with storm drain facilities to deliver storm water to the fairway areas. A small portion of the south end of the property cannot be conveniently drained to the golf course fairways and is not included in the hydrology study. This area, however, will be included in more detail as a part of future studies. A HEC -1 model was developed for flood routing purposes. Two-day and five-day storms were developed in accordance with the manual. The 08/25/93 -12- to zH �o W 86" W IZ Q PiE. ot �3w . z a� 0 a � N Yl ar N0 U F� p20u]gaF Zo W Q N LU oQ\ N �. z to zH �o W 86" W IZ Q PiE. ot �3w . z a� 0 a � N it:rpt' I I i ' .i,J% II` f'.. ;� �t.l'•i,''1{ ,i 'l{: � ri',fj j� I;. �I� � fll t. .,1 , i I � ( :li-,I j' 1 l,Ilf..,Ifix l' ; !�';(, Ir, � f�,�) � !�t ., {,•,`� iii fil {�� ..� „i L''i•,: , I• i It till I � ! rr i :,r l , I, ., t :,r3 %.i ` ;II ,t i' r .,r.If {3t •r l' ,,! t• , !, (;1, 'r. ('.r'}, I },,,r I ,. i t: I t., , r I },l. '-,'� rOIL r; II>` ntlf +';t. l.., ,i;,1r,' I.I:,,,I i 1).'{m ir)i'I lin,si inn I '' r,tl i j"' I,t,!';u. j I �' (1;' I {'• rirt! x 11' t ul.%I ! Liu iii. �TI'1 I ' , I ) SANTA MARGARITA RIVER WATER MANAGEMENT PROJECT 897 Murrieta CA 92564 909/678-6328 CRWM discussion for 7/89 SEPARATING STORAGE/PERCOLATION FUNCTION!-'; The key to preventing a lose of infiltration capacity from sedimentation during is storm event lies in providing is combination of filters, stilling basins and selective intakes for subsurface percolation systems. The proposed system for Sierra Lakes provides none of these.. While its diversion structures would indeed guide first -..- flush particulate matter to retention. they would not intercept the mass of material typically found in runoff from major storms. It is likely this material would immediately obstruct soil pores during a storm event. It is true that as the watershed subarea feeding these infiltration basins is developed the volume of silt reaching them will be progressively reduced, but even when this entire area is completely built over a considerable amount of material will be washed to the basins during a major storm. For this reason it would be prudent to install percolation structures that will function effectively throughout a storm event despite inflows of sediment to the basin.. Attempts at multiple Use deserve careful scrutiny because stormflows create conditions that minimize the effectiveness of infiltration basins precisely when they are most critical in preventing the release of floodwaters. comment to CRWM re: RCFC & WC O retention basin design - 8/89 in general, the largest storage facility should funtion as a stilling basin if the system is to precipitate the maximum amount of particles from starmwater before introducing it into groundwater. The water that is transferred to percolation facilities must be made as clean as practicable so as to avoid plugging the soil pores.. There seems to be a common blind spot among civil engineers and hydrolooists that causes them to attempt to combine storage and percolation functions into a single facility,. While this multiple usage seems sensible at first glance careful consideration will show that the basin which receives stormwater is certain to be highly agitated during a storm event due to inflowing water. This causes it to maintain soil particles in suspension so that they follow the fastest flows into underlying soils, plugging the most effective interface areas. If total, the more efficient the percolation. the more rapidly it will be diminished. A system that separates infiltration from storage facilities will eliminate this most critical drawback of onsite retention. When water is bled from the cleanest part of a storage basin and fed to percolation facilities as they are able to handle it, the remaining waters are given time to still their motion and so allow particles to settle out., This may seem complicated but as the accompanying diagrams indicate. it need not be. The savings in grading costs that come from downsizing storage faciities would balance off the cost of remote percolation facilities on most sites. The greater flexibility in site design that derives from separating storage and percolation facilities may be even more beneficial. A balance needs to be reached between the amount of fine Particulate matter reaching the percolation facilities. the soil contact area of these facilities, and the capacity of subsurface soils to transmit particles laterally. Assuming that the watershed of this site will Produce Progressively less particulate matter as it is developed. the time will come when stormwaters will contain only an insignificant volume of particles. on !ces' This benefit is more than just an incidental one, as the flood damage that has resulted from silt in creekbeds, the cost of removing silt from creekbeds, and the cost of cleannino storage basins has been a major drain on public wealth. (cite Camp Pendleton costs for cleaning its infiltration ponds after the 1993 flooding) The flow of soil particles during a rainstorm is highly visible as muddy water but it is difficult to visualize the cumulative effects of of particles if one is not familiar with hydrogeology or has not viewed soil Profiles of creekbeds., REMOTE AND ALTERNATE PERCOLATION SYSTEMS A percolation basin may be relatively small and need not be immediately adjacent to the stilling basin. It may even be in a remote area or all percolation may take place in a subsurface drainge field fed from the stilling basin. The critical element is removal of most particulate matter from water that is guided to a percolation site. This may be accomplished by providing a floating inlet that takes in water from near the surface of the storage basin and feeds it to remote Percolation areas. This will permit most heavy particles to settle out and will allow the use of fabric filters, given careful design and maintenance of the inlet structure. Such an inlet could be stored beneath the soil surface in a manner that makes it deploy automatically during a storm event. it may be stored indoors to prevent deterioration of its materials and only installed when ALERT systems indicate a potential for major rainfall volumes.. It may be necessary to build this inlet into a permanent structure of some kind, however, due to generally outdated and inflexible policies, specifications and regulations at all levels of government. The remote percolation may consist in: - Portions of a playground or golf course graded as basins and protected from inflows of turbid starmwater. - Open areas throughout the site that have been underlain by draintile or drainage mate. (This may be accomplished during mass grading. with careful management of soil return to provide lateral drainage with stratified soils, gootexiles, or other devices.) - Areas paved with porous asphalt or concrete., These would be designed to accept only g_1:. gra. waters from the storage basins and percolate it into subsoil at a rate that is adequate for preventing floodwater runoff. X * X ADDITIONAL COMMENT RE: SIERRA LAKES STORMDRAIN PLANNING Figure 4 of the B-93 concept diagrams a catch basin in the street. a storm drain pipe leading to a diversion structure and a pipe leading from that to a water quality wetland.. While this seems simple and straightforward enough, several questions deserves answers.. 1. Assuming the houselat were graded so that it could retain all its rainfall and feed this to the street over an extended period of time during major storms, could not this entire system be downsized significantly'? 2. Assuming the house lat incorporated "dry wells" capable of transferring its rainfall to groundwater within a specified period after a major storm events, could not the diagrammed facilities be downsized even more'? 3. Assuming all pavement was porous so that underlying gravels provided a detention function. could not these faclities be downsized even more or even eliminated entirely'? Note that such planning would cause most particulate matter to be prevented from entering storage basins, greatly reducing problems with clogging soil pares where these also perform an infiltration role. -a.t.t s an. . ..... -pp ......... Stormwater sandOration: A solution or a problem? by Ben R. Urbonas, P.E., Chief, Master Planning and South Platte River Programs, John T. Doerfer, Project Hydrologist, Master Planning Program and L. Scott 'Bicker, P.E., Executive Director, Urban Drainage and Flood Control District, Denver, CO he results of tests conducted re- cently reveal caution needs to be observed when using sand filters for stormwater quality management. Stud- ies done in Lakewood, Colorado, indicate sand filters lose their effectiveness dra- matically when the flow through rate de- creases proportionate to total suspended solids accumulating on the filter surface. This decrease in the flowthrough rate re- sults in either the stormwater bypassing the filters or creating large and prolonged ponding areas. The use of sand filters for stormwater quality management has been taking place since the mid-1980s. Other types of me- dia filters have also been investigated as stormwater Best Management Practices such as peat and sand -and -peat mix fil- ters, and compost and compost -and -sand layered filters. Little has been reported about hydraulic performance The latter two types reported rapid clog- ging and mixed success in their ability to remove a number of constituents from stormwater. Sand filters are currently be- ing used with increasing frequency in the United States. While literature contains reports about their ability to remove pol- lutants, little has been reported on their hydraulic performance. Since 1994 the Urban Drainage and Flood Control District in Denver, Colo- rado has been conducting field and labo- ratory investigations in the water quality enhancement and hydraulic performance of stormwater sand filters. A number of different sand gradations were tested in the laboratory, resulting in the selection of concrete sand for a field test in Lake- wood, Colorado. The sand gradation demonstrated a good balance between filt8ring effective- ness and hydraulic conductivity. This type of sand appears to be the most common mix in use today at existing field installa- tions reported in the literature. JULY 1996 Also, the total suspended solids char- acteristics at the field test site were found to he comparable to those reported by the Environmental Protection Agency and appear typical of that often found in ur- ban stormwater runoff. The water quality performance characteristics of the district's test sand filter were found to be comparable to those reported in the lit- erature. Sand f">Iters lose hydraulic conductivity very rapidly However, this was true only for the frac- tion of the runoff that actually flowed through the filter and not for the amount of stormwater runoff that bypassed the filter. It became clear early in the field tests that the sand filter began to lose hydrau- lic conductivity very quickly. This led the authors to conclude that, unless there is substantial detention volume upstream of sand filters that will capture and slowly release stormwater, much of it will either bypass the filter or result in large and pro- longed ponding areas on the surface. The trend in the test filter's unit hy- draulic flow through rate (feet per hour per square foot of sand filter) was a func- tion of the cumulative total of suspended solids removed by each square foot of the filter's surface area. Immediately after the sand was installed its flow through rate was in excess of three feet per hour. This quickly diminished to less than 0.075 feet per hour as 0.4 to 0.6 pound. of total sus- pended solids per square foot of filter area accumulated on its surface. The accumu- lation of 0.4 pounds of filtrate per square foot of surface area is equal to approxi- mately 1/16 inch thick layer of total sus- pended solids filtrate veneer on top of the sand. The final flow through rate of 0.05 feet per hour (0.006 gpm/square-foot.), which in the test facility was reached af- ter only a few storms, is approximately equal to one-tenth of the design rate rec- ommended by several local stormwater APWA Reporter criteria manuals that permit or require fil- ters. Rapid reduction in flow through rates quickly raised a red flag The rapid reduction in flow through rate presented a red flag to the authors about the practice being used today in the de- sign of sand filters for stormwater man- agement. During the 1995 summer sea- son of operation, more than one half of all runoff events exceeded the combined capacity of the filter and the upstream sur- charge volume of the test facility to "cap- ture" the storm's entire runoff. This re- sulted in a total suspended solids removal rate during the summer monitoring sea- son of less than 15 per cent after all the flow bypass volume was accounted for. This compares poorly with the more than 85 per cent total suspended solids removal rates reported in the literature and con- firmed by district's field tests for that por- tion of the runoff that actually flowed through the filter. Flow bypasses were anticipated in the design of this test installation because it was designed to be "stressed" so as to re- veal quickly how fast such a facility would need maintenance. However, the rate at which it sealed and the much -reduced volume that flowed through the filter was a surprise. Clearly, if these findings are indica- tive of other installations, either an aggres- sive maintenance program is needed to keep the filter's surface area clean, filters need to be much larger than current de- sign recommendations suggest, or the fil- ters need to be equipped with substantial stormwater detention volume upstream. Any of these scenarios have signifi- -ant economic and operational conse- luences that need to be considered. The authors acknowledge the cooperation of the City )f Lakewood, Colorado, as well as the help of Rich- trd Ommert and Curtis Neufeld, engineering stu- lent interns with the district, who collected and ana- yzed the field data. For more information, call Jrbonas at (303)455-6277. 23 City of Fontana C A L I F O R N I A FAX COMMUNICATIONS FROM FAX NUMBER (909) 350-6618 PLEASE DELIVER THE FOLLOWING PAGES TO: Company: ? F 77E 7-1257H&2 f�- SSS _ / 2 - Name: �� �}/✓ SGr1j4�US©N Fax Number:, 714-) 4-34' — 6120 Phone Number: 14 4--' From: F75L- 1"PL M O� - I A,)0 I I Phone NumbeW05) 3-r,,0-6,64-1 Total Number of Pages: Date: J/' 30-53 Time: (including cover sheet) Message: ID 5 /3Ok //y� ;,�>% I'�47 j Tv -�� SO/` f z5 cc: FAX CHARGE IS: $3.00 1ST PAGE (EXCLUDING COVER SHEET) $1.50 THEREAFTER. PLEASE MAKE CHECK PAYABLE TO THE CITY OF FONTANA IN THE AMOUNT OF $ PLEASE MAIL TO: CITY OF FONTANA, P.O. BOX 518, FONTANA, CA 92334 FROM: Name Company/Firm Address NOTE: Please return this cover sheet with Payment Phone No. (Account No. 010-0316-2300) 8353 SIERRA AVENUE (RO. BOX 518) o FONTANA, CALIFORNIA 92334-0518 o (714) 350-7800 SISTER CITY— KAMLOOPS, B.C. CANADA g recycled paper ja �Lf� J�0 0 as; �..sc+o"x`i:r,�'r�s�A.t, :L•^�t��•:.;:p�- For Drolno',.:�I.I. . UJI-C"IterQuolit- V h � � and CSS anog e' n -3i�PH=-_ cam, si?k::��AtlfS-•+`: � .. - . PETER STRHRE • BEN URBONAS 0 :_ STORMWATER DETENTION For Drainage, Water Quality, and CSO Management Peter Stahre Malmo Water and Sewer Works Malmo, Sweden Ben Urbonas Urban Drainage and Flood Control District Denver, Colorado Prentice Hall Englewood Cliffs, New Jersey 07632 Library of Congress Cataloging -In -Publication Data Stahre. Peter. Storawater detention For drainage, water quality, and CSO management i by Peter Stahre and Ben Urbonas. P. cm. Includes bibliographies and Index. ISBN 0-13-849837-7 I. Storm water retention basins. 2. Urban runoFf. I. Urbonas, Den. II. Tltle. TD665.S73 1990 628'.21--dc20 89-33449 CIP Editorial/production supervision and interior design: Brendan M. Stewart Cover design: Lundgren Graphics, Ltd. Manufacturing buyer: Mary Ann Gloriande This book can be made available to businesses and organizations at a special discount when ordered in large quantities. For more information contact: Prentice -Hall, Inc. Special Sales and Markets College Division Englewood Cliffs, N.J. 07632 © 1990 by Prentice -Hall, Inc. A Division of Simon & Schuster Englewood Cliffs, New Jersey 07632 All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission in writing from the publisher. Printed in the United States of America 10 9 8 7 6 5 4 3 ISBN 0-13-84983?-? Prentice -Hall International (UK) Limited, London Prentice -Hall of Australia Pty. Limited, Sydney Prentice -Hall Canada Inc., Toronto Prentice -Hall Hispanoamericana, S.A., Mexico Prentice -Hall of India Private Limited, New Delhi Prentice -Hall of Japan, Inc., Tokyo Simon & Schuster Asia Pte. 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'o `O O a y a ny N vi w a �. n S 'O n `< <G C '» `< O �n n vo a a• a O CD CD O CD N w 0 O 0. a^ p y' CD Z a o ? „CD, CD a CD .o puo o ?' y a CDCD i w p a ti c o o ao n R cDall n a a a P F ti o vn n a C^D C G O oaq CC" G M '= o K m S C b (D P"Si f ��' cnD w cD ° .. drainage area maps, watershed soils, development, cover assumptions, rainfall intensity -duration characteristics, routing schematic, and other details are presented in Appendix B. D. Golf Course Flood Water Storage Basins Using the current golf course grading plan, the volume of flood water storage that could be developed within the fairway areas was determined. Basin stage -storage -discharge relationships were computed and input into the HECA model. E. Flood Routing -Infiltration Study Findings The previous field infiltration tests had identified infiltration rates of up to 30 feet per day. For the flood routing -infiltration study a value of 15 feet per day was assumed. Infiltration was modeled as a "divert" in the HEC -1 model. To determine the required infiltration area at this infiltration rate, a modeling criteria was established that required the golf course basins to be drained in 24 hours. Under this criteria, it was found that 30 acres of infiltration area would be required. This study indicated that the infiltration concept is hydrologically feasible, based on the generalized natural soil infiltration rates determined from the previous field tests, and the simplified rate assumed for the study described above. To verify its feasibility in the context of the actual golf course environment, and to verify that a reliable infiltration facility can be developed which can practically be maintained to retain its infiltration capacity over the years, the present study was undertaken. Among other 08/25/93 -13- things, the present study considers factors not previously evaluated, such as the effects of varying head and siltation. F. Infiltration Facility Concept Preparatory to undertaking the field studies described herein, an infiltration facility concept was developed which met the following criteria: ■ Infiltration effectiveness: Drain the golf course fairways within an acceptable time. ■ Maintainability: Be capable of restoration to the design infiltration capacity at acceptable cost. ■ Accessibility: Be easily accessed for inspection and maintenance. ■ Reliability: Be. impervious to mechanical damage, structural deterioration, corrosion, chemical contamination, and other foreseeable hazards. ■ Compatibility: Blend in gracefully with the golf course. If possible, serve as an occasionally useable part of the golf course, such as a sand trap or hunker. The most promising configuration that meets these requirements is a concept reminiscent of the simple sand filters used in municipal water treatment facilities in the 19th century. It consists of a layer of filter sand supported by a layer of gravel placed on the subgrade soil beneath the surface of the golf course fairway. The gravel layer, which transmits water to the native soil, is much larger in surface area than the sand filter. The portion of the gravel layer outside of the sand filter is covered by native 08/25/93 -14- soil and golf course turf. Filter fabric is placed between the layers to prevent migration of fines into the coarser media, with resultant impairment of infiltration capacity. The concept described above is shown on Figure 5. The gravel layer, which in the test program was placed directly on the subgrade soil, is 18 inches thick. The particle size of the gravel is approximately 1.5 to 2 inches. Filter fabric is placed over the gravel layer to prevent the movement of fines into the gravel layer. The sand filter layer is 30 inches thick. Gradation of the sand and gravel are important considerations. It is intended that the sand filter perform as a rapid sand filter. Rapid sand filters generally are comprised of fairly course grained open graded sands varying from 0.5 millimeter to over 1 millimeter in size. The open graded condition of the sand will reduce the potential for stratification of the finer grained materials near the bottom of the filter, and provides maximum infiltration capacity. The rate of infiltration for rapid sand filters is about 125 million gallons per acre per day or approximately 2 gallons per minute per square foot. It will he important to achieve a rate of infiltration near this value in order to obtain a reasonable balance between the sand filter area and the area of infiltration beneath the gravel layer. Because of the importance of these parameters in developing a reliable infiltration system, a comprehensive 08/25/93 -15- infiltration testing procedure was developed to evaluate the various elements of the proposed sand filter concept. G. Water Quality Considerations The long-term performance of the infiltration system is influenced by the quality of the storm water. If sediment -laden storm water is allowed to enter the infiltration system the sediments will accumulate in the filter and gradually diminish the infiltration capacity. To avoid impairment of infiltration capacity the integrated concept presented herein incorporates water quality wetland facilities. These wetlands will be located on the golf course near the outlets of local storm drain facilities. First -flush storm runoff and urban nuisance flow will be removed from the drainage system and diverted to the water quality wetlands for treatment. Water entering the wetlands will be consumed by evapo-transpiration or will infiltrate into the ground after receiving the benefits of wetlands treatment. A typical water quality wetland is shown on Figure 4. Wetland operation and maintenance criteria are discussed in Section VII. Under this concept, pollutant -laden first -flush storm flows and urban nuisance flows are removed from the drainage system and never enter the infiltration facilities. During larger storms the relatively clean post -first -flush storm runoff will by-pass the water quality wetlands and proceed to the infiltration facilities. Without the first -flush pollutants these 08/25/93 -16- flows can be accommodated by the infiltration facilities. Monitoring and maintenance criteria are presented in Section VII. When the off-site watershed is fully developed its sediment production rate will be lower than it is now due to stabilization of the watershed and the implementation of water quality best management practices. In its existing condition, however, its surface soil is extremely erodible and sediment production is relatively high. The acceptance of this sediment -laden water into the Sierra Lakes water quality wetlands would result in a rapid accumulation of sediment, and the need for frequent cleanout. Since sediment removal requires removal of wetland vegetation, it is desirable to minimize the frequency of cleanout. For this reason, until the off-site watershed is stabilized by development, a temporary or interim off-site debris control facility will be needed. This facility will be located immediately adjacent to and upstream of Summit Avenue. Since this land is not currently owned by Lewis Homes, it has been assumed that the necessary rights can be acquired. 08/25/93 -17- III. FIELD INFILTRATION TEST SETUP This section describes the test facility which was constructed for the field infiltration tests described herein, the water delivery and metering system, the operational criteria, and the general filling and testing approach. A. Test Pit Location The location of the test pit which was used to conduct the various tests is in the vicinity of fairway I, as shown on Figure 2. This site was chosen because of its proximity to the source of water used to conduct the tests. B. Water Delivery and Metering The source of water used in conducting the tests was an on-site well located approximately 600 feet from the test pit. A pump was placed in the well approximately 400 feet below the surface. The water table is approximately 300 feet below the surface. The pump discharge line was fitted with both 3 -inch and 6 -inch flow meters. These two meters were necessary to accurately monitor flow to the test pit (Photograph Nos. 1, 2, and 3). Both meters were equipped with totalizer dials to record the total volume of water delivered to the test pit. The 3 -inch water meter was used to record the inflow to the pit for steady state flow conditions. The accuracy of this meter was approximately plus or minus 5 gallons per minute. Both the 3 -inch and 6 -inch meters were used to determine the flow delivered to the test pit during initial filling. 08/25/93 As- C. Steady State Flow Conditions Steady state flow conditions have been defined for purposes of this test as a condition where the level in the pit does not change by more than 1/100th of a foot over a one-hour period. One hour hold times were used at each test elevation level. After maintaining a constant water level for the one hour period, the inflow rate into the pit was recorded as the steady state infiltration rate at that particular water level. It should be noted that a steady state flow condition is further assured by the time required to fill the test pit. Prior to testing, it took approximately 8 hours to fill and maintain a full pit condition. D. Meter Verification In order to check the accuracy of the meter readings, the total number of gallons delivered to the pit was also recorded from the 3 -inch meter totalizer dials. The total number of gallons delivered to the pit over the one hour time period was used to compute of the total gallons per minute inflow. This computed inflow rate was compared with the actual meter needle readings. In addition to this check, the time for the water level to drop between test levels was recorded and the approximate infiltration rate was computed based on the estimated volume in the pit between test levels. E. Test Pit Filling Because of the volume of the test pit, it was necessary to begin filling the pit between 10:00 p.m. and 11:00 p.m. in order to assure that the pit would he filled in time to begin testing at daylight. Erosion control provisions were placed in the bottom of the test pit, when testing the various 08/25/93 -19- elements, to assure that the suhgrade soils and/or the other elements of the test pit configuration would not be eroded by the high flow rates used to fill the pit. F. Test Sequence The tests were conducted by filling the pit, reaching a steady state flow condition, documenting water level, time, and flow rate, and then allowing the water level in the pit to drop. At each water level increment the steady state flow condition was re-established and the water level, time, and flow rate were documented. 08/25/93 -20- W. FIELD INFILTRATION TEST PROGRAM A. Test Programs The following test programs were performed to evaluate the various elements of the infiltration concept. ■ Test Program No. 1: determine infiltration rate of the subgrade soil as a function of head. ■ Test Program No. 2: determine the infiltration rate of the subgrade soils, the gravel, and the filter fabric as a function of head. ■ Test Program No. 3: determine the infiltration rate of the subgrade soils, the gravel, the filter fabric, and the sand filter overlying the filter fabric as a function of head. ■ Test Program No. 4: determine the effect of various levels of siltation on the infiltration rate of the sand filter. ■ Test Program No. 5: determine the effect on infiltration rate recovery by removing contaminated layers of the sand filter and replacing them with clean sand. ■ Test Program No. 6: determine the infiltration rate of golf course turf placed over 30 inches of native soil materials as a function of head. B. Test Program No. 1 1. Test Pit Configuration The configuration for Test Program No. 1 is shown on Figure 6. The pit was excavated approximately 11 feet deep by approximately 25 -foot square at the base. The pit side slopes were excavated 08/25/93 -21- approximately 1.25 horizontal to 1 vertical. Two layers of 10 mil visqueen were placed around the side slopes to assure that all the percolated water passed through the base of the pit. A 2 -inch by 12 -inch timber frame was constructed on the floor of the pit to insure a 25 -foot square infiltration area. In an effort to reduce seepage around and under the visqueen liner, the visqueen liner was extended approximately 6 to 8 inches creating a cutoff below the bottom of the pit. The effect of creating this additional cutoff of the visqueen liner resulted in a net effective infiltration area dimension of approximately 27 -feet by 27 -feet. In the center of the pit, a 10 -foot staff gauge was installed. This staff gauge was a conventional survey rod graduated in 1/100 -foot increments (See Photograph Nos. 4, 5, 6, and 7). 2. Results of Test Program No.l The test results from Program No. 1 are shown on Figure 7. The figure shows that infiltration rate increases with head. For example, the infiltration rates at water levels of 4 feet and 6 feet were approximately 12 feet per day and 32 feet per day respectively. At a water depth of 9.6 feet, the infiltration rate is 59 feet per day. 3. Investigation of Edgc Conditions At the conclusion of Test Program No. 1, the visqueen was removed from the northwest corner of the test pit to investigate the extent of seepage behind the visqueen liner. A trench approximately 3 feet wide by 5 feet deep was excavated (See Photograph No. 8). 08/25/93 -22- Inspection of the wetted soil in the trench walls showed the water rose outside the visqueen to a level 5.5 feet above the bottom of the pit. Using this data point to establish the water surface elevation outside of the visqueen, the flownet shown on Figure 8 was constructed. Calculations were performed to estimate the affect of lateral seepage near the edges of the pit on the infiltration rates. The flownet and the resulting calculations indicate that the flow around and underneath the visqueen liner is greater than the flow near the center of the pit. The flownet findings are valuable in identifying the most efficient configuration for infiltration facilities. This subject is discussed further in the next section. C. Test Program No. 2 1. Test Pit Confi(miration The configuration for Test Program No. 2 is shown on Figure 9. For Program No. 2 an 18 -inch thick gravel layer with particle sizes from 1.5 inches to 2 inches was placed directly on the subgrade soils and covered with a filter fabric. The fabric used in the test was Mirafi 140N, a nonwoven material. Sandbags were placed on top of the fabric to secure it in position during filling of the pit. No other changes were made to the configuration used for Test Program No. 1 (See Photograph Nos. 9, 10, 11, and 12). 08/25/93 -23- 2. Results of Test Program No. 2 The results of Test Program No. 2 are shown on Figure 10. Figure 10 shows that placement of the gravel layer and filter fabric resulted in a reduction of infiltration rate. The reduction ranges from approximately 15 feet per day at a water depth of 9.6 feet to approximately 4 feet per day at a water depth of 4 feet. This reduction is believed to be caused by the placement of the gravel layer directly on the subgrade material. Where the fine subgrade material works between the gravel particles, the porosity of the mixed media is less than that of either material by itself. This zone therefore becomes a restriction in the flow. For this reason it is planned to use filter fabric between the subgrade material and the gravel in the final design to prevent the mixing of different sized particles. D. Evaluation of 'rest Programs Nos. 1 and 2 1. Selection and Testing of Rapid Sand Filter Material The results of Test Programs Nos. 1 and 2 were used to determine the size of the sand filter which will overlay the gravel bed material beneath it. As stated previously, the sand filter should have the capacity to produce an infiltration rate of 2 gallons per minute per square foot. A number of varying sand gradations were obtained and tested in the lab to determine their flow characteristics. The sands examined included washed concrete sand, No. 30 silica sand, 08/25/93 -24- No. 20 silica sand, and No. 12 silica sand. A particle size analysis was performed and the resulting gradation plotted on Figure 11. The gradation plot shows that the washed concrete sand is a relatively well graded material. As mentioned earlier in this report, the most appropriate rapid sand filter material would be a material that is relatively open graded with very few fines. The washed concrete sand does not exhibit these characteristics. However, the silica sands begin to approach a relatively open graded material. Based on the particle size analysis, the No. 12 silica sand was selected as the material most likely to produce the desired flow rate of 2 gallons per minute per square foot and he capable of filtering fine grained materials. All of the above mentioned sands were subjected to flow tests at the RMA Group laboratory facilities. The data obtained from these tests were the material permeability and flow rate per square foot for 0.5 foot of head loss. The laboratory flow test data of the No. 12 silica sand shown is on Figure 12. The tabulated data indicate that the No. 12 silica sand has a permeability of approximately 0.36 feet per minute and exhibits a flow rate of 2.7 gallons per minute per square foot resulting from 0.5 foot of head loss. The material is relatively coarse and may exhibit a tendency to move finer grain materials at a deeper depth through the filter. The effect of silt 08/25/93 -25- migration through the sand filter was examined during Test Program No. 4. 2. Sizing of the Sand Filter Using the results of Test Program No. 2 and the results of the laboratory flow test data, the required sand filter area was determined. A number of computations were made assuming various dimensions for the sand filter. A sample computation assuming a 9 -foot square sand filter is shown on Figure 13. The computations shown represent a trial and error procedure where the objective is to balance the sand filter inflow with the subgrade inflow. For example, at a water level of 10 feet (6 feet of water on the sand filter surface) the discharge flowing through the sand filter using 1.8 gallons per minute per square foot generated 146 gallons per minute. Based on the laboratory flow test data, the head loss created by 1.8 gallons per minute per square foot is 1.67 feet. The remaining head available to drive the water through the filter fabric and the gravel layer and into the ground is 8.33 feet. Using the results of Test Program No. 2 and entering the curve with 8.33 -foot of available head, indicates that 0.196 gpm/ft' or 143 gallons per minute can be infiltrated through the subgrade soils. Comparing 143 gallons per minute through the subgrade with 146 gallons per minute through the sand filter shows close agreement. This computational procedure was repeated for water levels of 8, 6, and 5 feet giving infiltration rates of 105, 61, and 08/25/93 -26- 41 gallons per minute, respectively. Based on these computations, a sand filter dimension of 9 -foot square was determined as the appropriate configuration for Test Program No. 3. E. Test Program No. 3 1. Test Pit Configuration The configuration for Test Program No. 3 is shown on Figure 14. To construct the sand filter area required for Test Program No. 3, a 9 -foot square frame was constructed on top of the filter fabric in the center of the pit area used for Test Program No. 2. Backfill was placed up against this frame and then raised using side slopes of approximately 1.25 horizontal to 1 vertical. The visqueen previously installed for Test Program Nos. 1 and 2 was left in place (See Photograph No. 13). Two additional layers of 10 mil, visqueen were also placed completely around the side slopes of the pit and down to the bottom of the 9 -foot square frame to assure that the entire flow passed through the 9 -foot square area. The staff gauge used in the previous test programs remained in place for monitoring the test water levels. An important consideration in constructing Test Program No. 3 was the delivery of water to the test pit. When delivering water to the pit, the surface of the sand filter should not be disturbed or eroded. If disturbance or erosion occurred, the sand filter thickness would change, introducing uncertainty into the test results. In order to 08/25/93 -27- achieve a uniform, nonerosive delivery of water to the pit, a 6 -inch perforated PVC pipe was installed around the perimeter of the pit outside of the sand filter, but below the surface level of the sand (Figure 14). The pipe was laid in a gravel pack with the perforations on the bottom of the pipe (See Photograph No. 14). When the water was delivered to this PVC pipe at high flow rates, energy was dispersed by flowing up through the gravel before reaching the top surface of the sand. After installing the PVC pipe, No. 12 silica sand was placed in the filter area and compacted (See Photograph Nos. 15 and 16). Two piezometer wells were installed on opposite sides of the pit to determine the loss of head due to flow through the sand filter. 2. Results of Test Program No.3 The results of Test Program No. 3 are shown on Figure 15. As a result of installing the sand filter, an additional reduction in infiltration rate occurred. At the 9.6 -foot water level, the reduction was approximately 7 feet per day. At the 8 -foot water level, the reduction was approximately 5 feet per day, and at the 6 -foot water level, it was approximately 2 feet per day, compared to Test Program No. 2. The infiltration rate curve computed from the lab tests is also shown on Figure 15. The computed infiltration rate curve predicted a greater loss of infiltration rate than actually occurred. This result 08/25/93 -28- indicates that the loss of head through the sand filter, as constructed in the field, was not as large as measured in the laboratory. The infiltration rate curve from the surface of the sand to almost 2 feet above the surface shows a higher rate than was measured in Test Programs Nos. 1 and 2. Infiltration rates of approximately 20 feet per day were measured in this depth range. In this range, the change in head had almost no influence on the infiltration rate. This apparent increase in infiltration rate can he explained as a result of the difference in the capacity of the filter at this low water depth to the capacity of the gravel layer beneath it. Flows are restricted through the sand filter to a larger degree than they are in the gravel layer beneath it. The greater capacity of the gravel layer beneath the sand filter, in both storage volume and flow capability, is essentially drawing the flow through the sand filter at a higher rate than would occur if the sand filter had a greater capacity at this low head. F. Test Program No. 4 Test Pit Confi<furation The configuration for Test Program No. 4 is shown on Figure 16. The configuration for Test Program No. 4 is identical to that used for Test Program No. 3 with the exception that a layer of silt is placed on the surface of the sand. The silt materials used for this test were obtained from the Owl Rock Plant in Lytle Creek. 08/25/93 -29- Because of the granular nature of the native soils, there was insufficient silt available on-site to economically produce the volume of material needed to perform the tests. Therefore, silt materials determined by the geotechnical consultants to closely represent the actual silt materials on the site were obtained from the Owl Rock Plant and used for testing purposes. The particle size analysis of the silt indicated the percentage of material passing the No. 100 and 200 sieves was 92 and 76, respectively (see Appendix C). Three levels of siltation were used in Test Program No. 4. For the initial testing of the siltation effects, 1.5 inches of silt was applied to the filter (Test 4A). The second application of silt included an additional 1.5 inches of silt (Test 4B), and finally, the third application of silt included another 1.5 inches of silt (Test 4C) for a total of 4.5 inches of silt (See Photograph Nos. 17 and 18). 2. Results of Test Pror?ram No. 4 The results of the individual silt tests are shown on Figure 17. This Figure shows that a continuing reduction of infiltration rate occurred due to siltation. The application of the first 1.5 inches of silt created a reduction in infiltration rate of about 5 feet per day. The addition of the second 1.5 inches of silt created an additional reduction in infiltration rate of 4 feet per day, and the third 1.5 inches of silt resulted in a further reduction in infiltration rate of approximately 1 foot per day. With a total silt application of 4.5 08/25/93 -30- inches, the infiltration rate at the 9.6 water level (approximately 6 foot of depth on the sand filter) was approximately 30 feet per day. With water at the 8 -foot and 6 -foot levels (4 -foot and 2 -foot depth levels on the sand filter), infiltration rates of approximately 20 feet per day and 10 feet per day of infiltration were measured, respectively. At the completion of each individual test, drive samples were taken through the sand filter at 6 inch increments (See Photograph Nos. 19 and 20). These samples were taken to the laboratory for particle size analyses and flow tests. The percentage of the material contained in the samples, passing the No. 200 sieve, is plotted on Figure 18 (refer to Appendix C). For each 6 -inch increment of depth in the sand filter, the percentage of material passing the No. 200 sieve is shown. For Test Program No. 4A, approximately 6 percent passing the No. 200 sieve was accumulated in the upper 6 inches. For Tests 4B and 4C, (3 and 4.5 inches of silt applied), approximately 11 percent and 12 percent of the material passing the No. 200 sieve was contained in the upper 6 inches, respectively. For Test 4A, approximately 3 percent of the material passing the No. 200 sieve was contained within the 6 to 12 -inch layer, and for Tests 4B and 4C approximately 5 percent and 8 percent of material passing the No. 200 sieve was contained in the second layer from 08/25/93 -31- 6 to 12 inches, respectively. As we go deeper into the sand filter, we find a continuing drop in the percentage of material passing the No. 200 sieve in the filter. From a depth of 18 to 30 inches within the filter, we find that the percent of material passing the No. 200 sieve is approximately 1 percent, or essentially equivalent to the original clean silica sand. It is concluded from the test plots that, for the three tests conducted, the migration of the silt materials did not progress much bclow a depth of 18 to 20 inches in the filter. As the filter sand was removed from the test pit, the filter material overlying the gravel layer was examined. This examination indicated little or no fine material accumulated on the fabric itself further verifying that the migration of silts did not progress to the complete depth of the filter. G. Test Program No. 5 1. Test Pit Configuration The test configuration for Test Program No. 5 is shown on Figure 19. The configuration for Test Program No. 5 is identical to Test Program No. 4. The contaminated upper layers of the sand filter were removed and replaced with clean sand. During the removal process, it was observed that the majority of the siltation occurred in the upper 10 inches of the filter. Based on these observations, 10 inches were removed and replaced with clean silica sand (See Photograph Nos. 21, 22, and 23). 08/25/93 -32- relatively high when compared to existing water conservation spreading grounds, but because the test did not address the long- term accumulation of silts in the turf and soil zone, it is not planned to take credit for infiltration through the turfed fairway areas in the design of the flood control system. However, it should be kept in mind that even with a relatively low infiltration rate, the large area of turf within the fairways will infiltrate substantial amounts of water over and above the design requirements. 08/25/93 -34- V. DISCUSSION OF TEST PROGRAM RESULTS A. Evaluation of Laboratory Flow Test Data and Piezometer Data The laboratory test data for the No. 12 silica sand was used to compute the anticipated loss of head through the sand filter for different flow rates. These computed losses were compared against the loss of head as determined from the piezometers. These comparisons were made for Test Program Nos. 3, 4A, 413, and 4C. The results of these comparisons are shown in Table 2 below: Table 2 Comparison of Computed (Laboratory) and Measured (Piezometers) Loss of Head in Feet through the Sand Filter Test Program Water Level 9.6 8.0 6.0 5.0 1 Comp. Meas. Comp. Meas. Comp. Meas. Comp. Meas. 3 1.67 N/A 1.20 0.50 0.88 0.60 0.87 0.75 4A 2.57 1.60 1.89 1.50 1.13 1.40 0.94 1.30 4B 2.85 3.00 1.65 2.85 1.14 2.90 0.53 3.05 4C 3.73 3.70 2.40 3.30 2.00 3.05 0.85 3.20 Comparing the results from Test Program No. 3 indicates fairly good agreement for the 6 -foot and 5 -foot water levels (2 -foot and 1 -foot of depth on the surface of the sand filter, respectively). At the higher water levels, agreement between the computed and measured values was poor. Aside from the obvious differences between laboratory and field conditions, the poor comparisons at the higher levels may he due to the fact that the 08/25/93 -35- laboratory tests were performed under low head conditions, i.e. 1 foot. For the 6 -foot and 5 -foot water levels, the head on the filter is closer to the laboratory conditions. For Tests 4A, 4B, and 4C, the laboratory test data was used to compute the loss of head through each 6 -inch increment of depth through the sand filter for each steady state flow condition. The computed losses through each 6 -inch increment were accumulated to determine the total loss of head through the 30 -inch thick sand for each steady state condition. For Test 4A, the loss in piezometric head was reasonably close to the computed values except for the 9.6 -foot water level. This result may have occurred for the same reason as described above for the unsilted sand filter. For Tests 4B and 4C, the loss in piezometric head agrees quite closely with the computed losses for the 9.6 water level. For the 6- and 5 -foot testing levels, the piezometric losses were significantly greater than the losses computed from the laboratory data. The piezometric losses also do not vary significantly with head. Figure 17 shows that the addition of the third 1.5 inches of silt (Test 4C) did not significantly further reduce the infiltration rates recorded after the second application of silt (Test 413). Since the piezometric head loss for Test 4C is only slightly higher than for Test 4B, it appears consistent with measured infiltration rates (Figure 17). It can be concluded that the computed loss of head through the sand filter based on laboratory flow tests showed reasonably good agreement for the 08/25/93 -36- lower operating heads for the clean and the marginally silted sand filter. The effect of heavier siltation significantly increased the piezometric losses which were not reflected in the computed losses, based on the laboratory test data, for the water levels of 8 feet and lower. B. Flownet Analyses 1. Flownet Construction As mentioned previously, a trench was excavated at the northwest corner of the test pit to examine the extent of seepage which occurred beneath the visclucen liner. This inspection indicated moist soils to a level of about 5.5 feet above the bottom of the test pit. It is reasonable to conclude that this level of seepage occurred during the highest testing level, or the 9.6 -foot level. This single data point, representing a loss of head of approximately 4.1 feet (9.6 feet minus 5.5 feet) was used to sketch the flownet. The flownet is shown on Figure S. The flow lines are shown as solid lines. The equipotential lines are shown as dashed lines. A total of nine flow paths have been sketched. The net has been constructed assuming a two-dimensional flow condition exists, and that Darcy's permeability coefficient, k, is a constant. It was also assumed that the visqueen liner was an effective impermeable membrane. The equipotential lines were constructed with equal loss of head of 08/25/93 -37- 1 foot. The intersection of the flow lines and the equipotential lines were drawn perpendicular and a "square" configuration maintained as much as possible. 2. Foownet Analvses When the flownet is properly constructed, the flow through each path will be the same. For the 9.6 -foot water level, the steady state flow was 225 gpm or 0.309 gpm/ft' (729 square foot infiltration area). Assuming a 1 -foot wide strip of a length equal to one half of the pit width (13.5 feet), the total flow through the strip is 4.17 gpm. Since each flow path carries the same flow, the infiltration along the 13.5 -foot long strip can he determined on a per foot basis by scaling the length of the individual elements of the flownet. Performing the analysis described above indicates that approximately 30 percent of the total infiltration occurs near the edge of the test pit. This result suggests that the use of relatively long and narrow sand/gravel filter and infiltration areas will be more efficient than areas which are more square in configuration. The proposed infiltration concept will not he constructed in the field with visquecn lined side slopes. Therefore, the edge flow condition described will not be as pronounced as in the test case. The adjacent soils; however, will have significantly Iower permeabilities than the sand and gravel materials creating a flow condition similar to that shown by the flownet diagram, but to a lesser degree. 08/25/93 -38- C. Effective Infiltration Rates The flownet analyses has indicated that, for the test pit configuration, the flow beneath and laterally to the visqueen is a significant portion of the total flow. Larger infiltration areas than were used in field tests will be used within the golf course areas. The use of these larger areas will reduce the proportion of the total flow which passes through the edges of the infiltration area. This suggests that the average infiltration rates determined from the field test be adjusted to reflect the more predominate rates near the center of the pit which are not affected by the edge conditions. To account for the edge effects, the flow net studies were used to compute adjustment factors to be applied to the recommended design infiltration rate curve (Section VI). These adjustment factors are to be applied to all ordinates of the curve dependent upon the width of the infiltration area. The following table indicates the required adjustment factors: Table 3 Adjustment Factors to be Applied to Infiltration Rate Design Curve Ordinates for Varying Infiltration Area Widths Infiltration Area Width, Feet Adjustment Factor to be Applied to Design Curve Ordinates 27 1.00 30 0.96 60 0.79 120 0.71 180 0.68 240 0.66 08/25/93 -39- D. Size Relationship or Sand Filter Area to Infiltration Area The results of Test Program No. 3 indicated that the 9 -foot square sand filter area produced a flow rate per square foot of 1.80 gpm/ftz. This configuration represented a balanced condition where the flow delivered by the filter was equal to the infiltration capacity of the subgrade soils. For the infiltration area of 729 ft', the sand filter was 11 percent of the infiltration area. 08/25/93 _40_ VI. RECOMMENDED DESIGN PARAMETERS A. Ratio of Sand Filter Area to Infiltration Area For design purposes, the sand filter area should not be less than 11 percent of the required infiltration area. The sand filter and infiltration areas should he relatively long and narrow. B. Infiltration Rate Curve 1. Sand Filter Maintenance Criteria The infiltration rate to be used for design of the infiltration system must be related to the proposed filter maintenance criteria. It is proposed that the criteria for filter maintenance he based on the level of filter siltation which occurred as a result of Test Program No. 4A. Figure 18 shows the level of silt materials passing the No. 200 sieve which were found to be in the various levels of the sand filter based on particle size analyses. It is proposed that the filter maintenance criteria be as follows: ■ The sand filter materials be removed and washed or replaced should materials passing the No. 200 sieve be found in percentages exceeding those defined by curve No. 4A of Figure 18 within any 6 -inch layer of the filter. 2. Recommended Infiltration Rate Curve The infiltration rate curve, as determined from Test Program No. 4A (Figure 17), should he used in Recharge Basin I for initial sizing of infiltration areas on the fairway and for developing 08/25/93 -41- C. stage -discharge curves for flood routing purposes. For ponding levels above the 10 -foot water level (6 feet above the sand filter), the infiltration rate shall be assumed a constant. The recommended infiltration rate curve is shown on Figure 23. This curve must be adjusted to reflect the proposed width of the infiltration area in accordance with Table 3 in Section V of this report. Infiltration rate curve 4A is site specific to recharge basin location 1. Individual infiltration rate curves will he developed for the other recharge basin locations as identified on Figure 2. The curves for the other locations will be based on testing to be conducted in the future at these locations. It is intended that only the infiltration rate of the subgrade soils be determined at the other recharge basin sites. Since the effect of the gravel, the filter fabric, and the filter sand is known, there is no need to repeat tests of these elements. Sand Filter/Gravel Layer Material Specifications 1. Gravel Laver The gravel layer shall be washed No. 2 gravel conforming to the following gradation: Sieve Size Percent Passini" 2" 100 1 1/2" 90 - 100 1" 5-40 3/4" 0- 15 3/8" 0 - 15 08/25/93 -42- 1a The specified gravel is readily available at Owl Rock, Lytle Creek, California. 2. Sand Filter The sand filter material shall he washed No. 12 silica sand conforming to the following gradation: Sieve Size Percent Passim No. 4 100 No. 8 96 - 100 No. 16 5 - 15 No. 30 0 - 10 No. 50 0 - 10 No. 100 0 - 5 No. 200 The No. 12 silica sand is readily available at Corona Industrial Sand, Corona, California. 3. Filter Fabric The filter fabric material shall he a nonwoven fabric, type 140N as manufactured by Mirafi or equal. The permeability of the filter fabric shall he equal or greater than 0.2 centimeter per second and the water flow rate shall he 285 gpm per square foot or greater. Safety Factor The design infiltration rate safety factor is the ratio of the expected actual infiltration rate to the recommended design infiltration rate. The various factors which contribute to additional infiltration, but were not included in the recommended design infiltration rate are the following: 08/25/93 -43- I . Infiltration through the golf course turf. Based on the preliminary hydrology studies of Recharge Basin I, the ponding area at the peak flood level covers an area of 6.9 acres. Of this 6.9 acres, 5.6 acres is required for underground infiltration area. Since the capacity of the subgrade soils in this 5.6 acre area is fully utilized, no additional water can he infiltrated. However, the acreage beyond the infiltration area, 1.3 acres, which is turfed, can infiltrate additional storm runoff. At a depth of 9.6 feet, the turfed infiltration rate is 9 feet per day (Figure 23). This rate of infiltration is equivalent to 2.1 feet per day over the gravel infiltration area of 5.6 acres. Including the turfed area will increase the recommended design infiltration rates for the 10-, 8-, and 6 -foot water levels as tabled below: Change in 9.0 1.3 = 2.1 +/day 5.6 Including the turfed areas of the fairways increases the design infiltration rate by an average of 5.6 percent. 08/25/93 -44- Infiltration % Change Water Level Rate, Ft/dav in Desiin Rate 9.6 +2.1 +6.5 8 +1.4 +5.6 6 +0.7 +4.8 9.0 1.3 = 2.1 +/day 5.6 Including the turfed areas of the fairways increases the design infiltration rate by an average of 5.6 percent. 08/25/93 -44- 2. Effect of underground storage in the gravel layer and sand filter and infiltration prior to ponding occurring on the sand filter surface. A preliminary flood routing study was made to determine the effect of utilizing the available underground storage within the gravel and sand materials. The volume of materials was estimated based on the required infiltration area of 5.6 acres and assuming 40 percent voids. The inflow hydrograph volume was altered by removing the volume within the leading edge of the hydrograph in the amount of the underground storage volume plus the water volume which infiltrated prior to filling all voids. By iterating the stage -discharge curve, an infiltration rate was finally determined where routing the altered hydrograph matched the results of routing the original hydrograph. This study showed that the effect of the underground storage was equivalent to an additional 2.3 feet per day of infiltration or an increase of approximately 9 percent. 3. The allocation of 50 percent of the difference between the moderately silted (Test 4A) infiltration curve and the clean sand test (Test Program No. 3) infiltration rate curve. It is reasonable to assume that one half of the difference in available infiltration capacity will be effective over the time period of gradual siltation. This difference (between Test Program Nos. 3 and 4A) in infiltration rates for the 10-, 8-, and 6 -foot water levels is tabled below: 08/25/93 -45- Change in Infiltration % Change Water Level Rate. Ft/dav* in Design Rate 9.6 2.5 7.5 8 1.5 10.0 6 3.0 20.3 * Determined from Figure 17 Using 50 percent of the siltation loss results in an average increase in the design infiltration rate of 12.6 percent. 4. Effect of 1.5 feet of ponding depth above the peak 100 -year flood level in the recharge basins. It is proposed to establish the overflow elevations of the escape routes at the downstream limits of recharge basins at 1.5 feet above the peak 100 -year flood levels. The effect of this additional surcharge storage was determined by flood routing. The recommended design infiltration curve ordinates (Figure 23) were reduced until the peak flood level rose 1.5 feet. The results of this analysis indicated that the design curve ordinates would have to he reduced 46 percent to create a 1.5 -foot rise in the peak flood level. This represents an additional safety factor of 46 percent or 16.3 feet per day of infiltration rate at the peak flood level. 08/25/93 -46- 5. The effect of increased infiltration rates for water depths above 6 feet. The recommended design infiltration rate curve (Figure 23) indicates a constant infiltration rate of 35.5 feet per day for water depths above 6 feet. This recommendation was made since the depth of water on the surface of the sand filter did not exceed 6 feet during infiltration testing. The test results indicate, however, that there is a clear, nearly linear trend indicating a continuing increase in infiltration rates with water depth. To evaluate the effect of this increased infiltration capacity, the slope of the infiltration rate curve was extrapolated as the average slope between the vertical and the slope of the curve between the 6- and 10 -foot ordinates. This revised curve was used as the stage -discharge relationship for a routing study where the effect of reducing the curve ordinates on the peak flood level was examined. This study indicated that to create a 1.5 -foot rise in the water surface elevation within the excess storage area, the design curve ordinates would have to be reduced by 56 percent. This represents an additional safety factor of 56 percent or 22 feet per day at the peak flood level using the extrapolated curve. Combining the effects of all five factors will increase the design infiltration rate by 5.6+9+12.6+46+56 = 129.2 percent representing a factor of safety of 2.3. 08/25/93 -47- It should be noted that a substantial additional factor of safety is inherent in the flood surcharge storage volume available in all recharge basins from the peak 100 -year flood level to the finish floor elevations of the adjacent residences. E. Possible Failure Modes and Mitigation All flood control and drainage systems are designed to meet defined regional and nationally accepted standards for capacity and performance. When the storm events exceed the accepted standard, overflow or other modes of "failure" can he expected. In this case, an infiltration system is being used to manage flood flows. The flood water is being diverted to the soil. The system must maintain its integrity during extreme storms and possible damage to property must be minimized. The following lists the possible modes of failure of the infiltration concept and methods built into the plan to reduce the problems of possible failure to insignificance. Problem: Sand filters do not her form res well as the clean filters used in the field test. Solution: a. Design the system to discount the filter capacity by using for filter capacity the infiltration rate for the filter after the application of 1.5 inches of silt. This is a 13 percent reduction compared to the new filter condition. This will result in an increase in total area 08/25/93 -48- required for the sand filter elements. Operation and maintenance criteria are set to maintain at least this capacity. b. The monitoring program will assume that the filters are at "design capacity." Golf course fairway infiltration rates of up to 10 feet per day will supplement sand filter infiltration rates but have not been included in the design capacity. C. The other factors discussed in Paragraph D above also significantly supplement infiltration rates but have not been included in the design capacity. Problem: A storm occurs which is more severe or of longer duration than the SBCTFCD 100 year multi -day storm, which was used for design. Solution: a. The golf course fairway basins will be designed to collectively hold the 100 -year multi -clay storm volume less the infiltration volume, and will include 3 foot of freeboard. b. An escape route will be designed in the facilities to assure that should the basins fill to 1.5 foot above their design elevation, they will start to discharge over a durable aesthetically attractive "spillway" swale. This escape route system will be incorporated into all inter -basin conveyances within the golf course. This will assure no loss of stored storm water due to embankment failures. At the southern boundary of the property, the overflow during these rare 08/25/93 -49- events will be directed into one or more streets at low velocities and aligned directly downstream. CPJ ,.rr- ►� 1, �� �� 08/25/93 -50- VII. OPERATION AND MAINTENANCE REQUIREMENTS The concept of managing storm flows by allowing ponded storm water to infiltrate within a golf course is feasible from a hydrologic standpoint, as demonstrated herein. In the field, success of the concept relies on consistent year -in, year -out performance of the drainage and flood flow delivery system, the quality of the flows to be infiltrated, and the condition of the sand filter infiltration facilities. All three of these must he monitored, maintained, and operated to assure they are always in good working condition so that Sierra Lakes and the downstream community are protected from floods and receive the planned water quality and water conservation benefits. The operation and maintenance program has three elements: ® Delivery system; 0 Water quality facilities; and a Sand filter infiltration facilities. A. Delivery System 1. Off -Site Flood Flows Off-site flows approach the Sierra Lakes project from the north. They will he collected in reinforced concrete pipe or box storm drains and brought under Summit Avenue to the Sierra Lakes project site. These collection facilities will be constructed by Lewis Homes as part of the regional flood control system. Within the site, the off-site flows will he carried in storm drains and golf course swales to the golf course sand filter infiltration facilities. They will 08/25/93 -51- also be carried from upstream fairway basins to downstream basins to efficiently distribute the water throughout the system. Distribution of flood flows within Sierra Lakes is a critical aspect of the system. The reinforced concrete facilities and surface swales that are currently proposed to transmit flood flows are shown on Figure 24. These are major flood control facilities and must be inspected, operated, and maintained as such. All the systems identified on Figure 24 are to be inspected each year between September 1 and September 15 to assure that they are clean, free of obstructions, structurally sound, and ready for the upcoming storm season. The inspection report to be filled out by the inspector is attached as Appendix F. The inspection will be conducted by the SBCTFCD. The inspection report will be signed by the inspector and a copy provided to the Fontana City Engineer. Any work required to bring the facilities up to designed conditions will be accomplished by the SBCTFCD prior to October 15. 2. On -Site Flood Flows On-site drainage and flood control facilities will normally be reinforced concrete facilities or durable drainage swales used to transport storm runoff from the in -tract drainage systems to the water gnality wetl.inds and sand filter infiltration facilities within the golf course. These facilities, the in -tract drainage systems, and all catch basins will be visually inspected annually between September 1 08/25/93 -52- and September 15. When annual visual inspections are not practicable due to pipe size diameters, T.V. inspections will be conducted every three years. These inspections will be conducted by the SBCTFCD, using the inspection report in Appendix F. The inspection report will be signed by the inspector and a copy provided to the Fontana City Engineer. B. Water Quality Facilities 1. Description and Purpose of Proposed Facilities The water quality wetlands are essential elements of the sand filter infiltration system and also further the goals of the NPDES water quality program. The wetlands will resemble the voluntary wetlands seen throughout the area at storm drain outlets. The water quality wetlands will be located near the outlets of the flood control and storm drain systems (Figure 24). They will remove urban nuisance flows from the storm drains. They will have more than enough capacity to handle nuisance flows. Nuisance flows occur throughout the year as a result of lawn watering, car washing, and the like. Nuisance flows carry some urban pollutants which will be removed or reduced in the water quality wetlands. The nuisance flows will nourish the wetland vegetation. Any water in excess of plant evapo-transpiration requirements will infiltrate or evaporate. 08/25/93 -53- First -flush storm flows which carry a large percentage of the storm water -borne pollutants from roofs, parking lots, streets, etc. will also be directed into the water quality wetlands. The water quality wetlands are designed to accommodate the runoff from a first -flush storm event. The inlets to the wetlands are designed so that when the wetland has received the first -flush and is filled to the design capacity, further inflow cannot occur. The relatively clean post -first -flush water by-passes the diversion structure and continues to the golf course fairways and the sand filter infiltration facilities. The purpose of the water quality wetlands is to collect and treat urban nuisance and first -flush flows. This process removes from the golf course sand filter infiltration facilities these flows and their attendant fine sediment, trash, litter, and other materials that would tend to reduce the infiltration rates. In addition, by consuming the nuisance flows, the wetlands will prevent the delivery of nutrients to the infiltration facilities, reducing the risk of algae growth. The growth of algae in sand filters is undesirable because it obstructs the pores in the sand and reduces the infiltration rate. There are two major mechanisms at work in these wetlands. The first is the removal of sediments by settling. Many urban runoff pollutants attach themselves to sediment particles. When the 08/25/93 -54- sediments settle to the bottom the pollutants go with them. Other pollutants are dissolved in the runoff. Some of the dissolved pollutants are taken up by the wetland plants. These pollutants are retained in the plant tissues. When pollutant levels in the bottom sediments and plant tissues reach prescribed values, the sediments and plant materials are removed and disposed of in an approved disposal site. ( 2. Objective of the Operation and Maintenance Program The objectives of the operation and maintenance program are: ■ To protect the water quality in the North Fontana area by monitoring removal of pollutants in the wetlands and maintaining the facilities in effective operating condition. ■ To assure the initial establishment of the vegetation and to stabilize its operation. ■ To prepare a comprehensive Field Operations Manual on the operation, maintenance, and monitoring of the wetlands. ■ To maintain the plants in the water duality wetlands in a healthy, robust condition for optimum pollutant removal. ■ To assure that routine maintenance requirements are identified and sediment removal activities are conducted in a timely manner to prevent any undesirable pollutant accumulation in the sediment. 08/25/93 -55- ■ To assure that plant harvesting activities are undertaken in a timely manner to remove the accumulated pollutants from the wetlands. ■ To maintain conditions which minimize nuisances to neighboring residences. 3. Maintenance Philosophy The maintenance philosophy will he based on the concept of regular monitoring to evaluate wetland conditions against established standards, followed, when necessary, by operation or maintenance routines to restore conditions to the established standard. 4. Maintenance Program Elements a. Security and housekeeping The wetlands will be supervised by golf course personnel to discourage trespass and vandalism. One of the routine inspection and maintenance activities will be to check security and perform routine cleanup and housekeeping. Also, the wetlands will be checked for insect or nuisance problems and corrective action initiated if necessary. b. Sediment removal and plant harvest Accumulated sediment volume will be monitored to assure that adequate water storage capacity is available. Sediment configuration will be monitored to assure that first -flush, nuisance flows, and supplemental irrigation water are well distributed among the plants. Pollutant concentrations in the 08/25/93 -56- sediment will be monitored so that sediment removals may be scheduled before unacceptable concentrations are reached. Plant materials will be monitored to assure that plant harvests and cleanouts are scheduled before excessive plant materials accumulate or pollutant concentrations in the plants reach undesirable levels. The wetlands will be designed so a portion of the area can be sectioned off for drainage and maintenance without disturbing the remainder. Every five to ten years, as indicated by the monitoring, a section of wetland can be isolated, drained, and cleared of sediment and excess plant materials. The cleanouts will be scheduled during the summer, when the remaining undisturbed wetlands can fully accommodate the nuisance flow. The re-establishment of plants in the cleaned area will be facilitated by transplanting of plants from the other wetland areas. The removed materials will be disposed of in an approved manner. -Experience has indicated that the materials will be suitable for disposal in a sanitary landfill. The monitoring program is specifically designed to allow the scheduling of cleanouts before pollutants reach unacceptable levels. 08/25/93 -57- C. Readiness, repair, and restoration The wetlands and appurtenances will be located at the outlets of the in -tract drainage systems. They will be subject to occasional storm flows. Berms and embankments may be subject to burrowing by animals. The annual maintenance cycle will provide for repairs and rehabilitation to be scheduled for the summer months so the facilities will be in good working order prior to each rainy season. 5. Interim Operation of the Wetland Facilities Upon completion of construction and planting of the facilities, Lewis Homes will engage a wetland specialist familiar with the facilities to operate, maintain, and monitor them on an interim basis until the following conditions have been met: ■ The facilities have operated through two storm seasons. ■ The Field Operations Manual has been completed and approved by SBCTFCD. o The Criteria for Plant Establishment presented below have been met. The purpose of this interim operation period of not less than two years is to assure that the wetland plants are well established and that operational procedures have stabilized and have been documented in the Field Operations Manual prior to turning the facilities over to the SBCTFCD. Criteria for plant establishment 08/25/93 -58- and operational stability are presented below. The Field Operations Manual is described in the following Section. a. Criteria for plant establishment The wetland plants will be considered to be established when they reach the following conditions: ■ Plant coverage of 90 percent of the bottom of the wetland area maintained for one year. b. Criteria for operational stability The facilities will be considered to have reached operational stability when the following conditions are achieved: ■ At least two winter rainy seasons have been experienced, with documentation of water levels and durations in the wetland. The reaction of the wetland plants to the storm inflow (storm damage, plant vigor, pollutant impact) will be documented. Sediment deposits, erosion, and storm damage at any of the facilities will be documented and repaired as required. C. Responsibilities of Wetland Specialist As each of the wetlands is developed, the establishment program described below will be implemented. For the first three months, a monitoring/maintenance visit by a wetland specialist will be conducted every two weeks. Thereafter, for the remainder of the period, the visits will be conducted monthly. 08/25/93 -59- 1. Monitoring/maintenance visit tasks The following tasks will be performed during each monitoring/maintenance visit. i Measure and record growth of selected plants. ® Estimate and record plant cover. ® Observe and document plant health, stress, disease, or pests. ■ Inspect and activate irrigation system to check effectiveness and adjust if necessary. ■ Inspect inflow distribution system and clear if necessary. ■ Check security. IN Pick up trash. IN ColIect sediment sample if scheduled. ® Check for storm damage, vandalism, animal burrows. ■ If water is ponded in wetland, record staff gage elevation, check clarity, color, and odor. ■ Check for insect infestations. ■ Fill out and sign "Wetland Monitoring and Inspection Form" (Appendix G). 2. Plant replacement The wetland specialist will be responsible for seeing that dead and damaged plants are removed and 08/25/93 -60- replaced monthly during the first three months and annually during late fall for the remainder of the interim period. 3. Maintenance The wetland specialist will be responsible for normal maintenance routines. Additional visits will be required for storm sampling, repair, and preparedness work. About April 15 each year the wetlands and appurtenant facilities will be reviewed for storm damage and wear. A work list will be prepared for execution during the summer. Maintenance crews will be scheduled during the summer to accomplish the work. About October 15 each year the facilities will be reviewed to assure they are in good condition for the winter storm season. Again, all components will be inspected. Any uncompleted work will be finished and any new damage will be repaired. Sediment accumulations and sediment pollutant concentrations will he monitored every year and recorded. This record will be examined every spring 08/25/93 -61- and used to predict the likely date for a sediment cleanout. 6. Preparation of the Wetland Field Operations Manual Each wetland facility has its own characteristics, some of which emerge only after the growth cycle is under way. The identification of individual wetland characteristics and responses to stimuli and the prescription of appropriate management responses is very important and requires the services of an experienced wetland specialist. By documenting the conditions that arise in a particular wetland and the management response that has proven to he most effective, the wetland specialist can assemble a Field Operations Manual that will allow experienced public works maintenance personnel to successfully perform this work. Preparation of the Field Operations Manual is the last of a series of activities in the planning and establishment of a wetland, marking the transition from wetland development to routine operation. It is intended that the Field Operations Manual stand alone as a training guide for future wetland operating personnel. Recognizing that there will be turnover in assigned staff, the manual will contain background information on the Sierra Lakes project, existing. and potential future drainage water quality problems, and the objectives and elements of integrated flood control -water conservation -water quality management system. 08/25/93 -62- It will contain as -built plans of each facility. It will contain a summary of the areas, capacities, and other engineering information about the facility. It will contain a brief description of the water -cleansing process that takes place in a wetland, to provide a context in which to explain the operation, maintenance, and monitoring requirements. It will contain a brief description of the build-up of pollutants in plant tissue and sediment and the need for monitoring and periodic removal of these materials. It will describe the soil moisture sensors in the wetland and explain how to use them to determine the need for supplemental irrigation. It will contain locations and descriptions of the water quality monitoring stations, the sampling criteria, and instructions on obtaining water samples for analysis. It will contain an operation, maintenance, and monitoring schedule and task list, and an inspection form. It will contain the acceptable standards for housekeeping, security, and maintenance of the facilities, and the procedures which have proven to be effective and efficient for correcting unsatisfactory conditions. A list of the necessary tools, equipment, manpower, and 08/25/93 -63- supplies, along with an estimate of the time required, will be included. It will contain the name and telephone number of the appropriate persons to call in the event of emergency or unusual conditions. It will contain descriptions of any insect or plant pests that were observed during the establishment period and the techniques that were effective in dealing with them. 7. Wetland Monitoring All wetlands will he monitored monthly to check for housekeeping conditions, maintenance conditions, security, vandalism, and insect infestations. In addition, 2 wetlands will be selected to represent pollutant accumulations from off-site and on-site drainage areas. These wetlands will be sampled each spring to determine pollutant levels in the sediments and in the plant tissues. C. Sand Filter Infiltration Facilities The sand filter infiltration facilities will he located in the golf course fairway areas. These areas will he graded to control the runoff from their tributary areas for infiltration into the native alluvial material. The actual infiltration areas will he elements of the golf course and will, therefore, enjoy the benefits of professional management and daily supervision and use. 08/25/93 -64- The sand filter infiltration areas will normally only receive flows during storms exceeding the first -flush storm. When this occurs, the early portion of the hydrograph will carry fine sediments and most of the pollutants into the water quality wetlands immediately upstream. The water quality wetlands will minimize the delivery of sediments and other material that would reduce the filter effectiveness. During major storm events, it can be expected that some sediment and clogging materials will he washed onto the surface of the filters. Some will enter the filter. In order to assure that adequate filter capacity is available to safely and reliably infiltrate larger floods, a monitoring program is required. The intent of the program is to alert the operators that remedial work is required to return the filters to their required capacity, if necessary. Based on the results of field tests previously described, economical testing procedures for the filter arc presented below. Figure 25 shows the locations for testing the sand filter infiltration areas. The tests are to he conducted between September 1 and September 15 each year until it can he demonstrated that less frequent testing is prudent and acceptable to the City of Fontana and SBCTFCD. The tests will include obtaining drive samples of the filter at each location shown. The samples will he taken in 6 -inch increments through the entire 30 -inch filter cross section. Particle size analyses will he performed for each sample to determine the percent of material passing the No. 200 sieve 08/25/93 -65- contained in each 6 -inches of the filter. If any increment of the sand filter contains material passing the No. 200 sieve exceeding the limits defined by Test 4A as shown on Figure 18, the contaminated portion of the filter shall be removed and either washed or replaced with new material. If the sand material is washed, a minimum of three random samples of the washed material shall be collected for a particle size analysis to assure that the material meets the original material gradation specification. Any new material shall also be sampled and tested against the new material gradation specifications. If contamination is not found in all locations of the sand filter infiltration area, only the contaminated areas need be restored to the as -built condition subject to the approval of the SBCTFCD. 08/25/93 -66- VIII. RESPONSIBILITY FOR OPERATION, MAINTENANCE, AND MONITORING Responsibility for operation and maintenance of the infiltration and water quality system is conveniently separated into its three components; the flood water and storm drain delivery system, the water quality wetlands, and the sand filter infiltration facilities. A. Flood Control and Storm Drain Delivery Systems The flood control and storm drain systems are traditional facilities that are designed and constructed by developers using plans approved by the responsible agencies. For the Sierra Lakes project, it is expected that the plans and specifications for these facilities will be prepared by Lewis Homes. They will be reviewed and approved by the City of Fontana and the SBCTFCD. As these facilities are constructed, they will be dedicated to SBCTFCD for operation and maintenance. The SBCTFCD will be provided sufficient rights-of-way to allow for the operation and maintenance of surface and underground facilities that are necessary for the successful performance of the system. B. Water Quality Wetlands The water quality wetlands will be. designed and constructed by Lewis Homes using plans and specifications approved by the City of Fontana and the SBCTFCD. To assure the successful development of the wetland facilities into the Sierra Lakes project and provide for their satisfactory long-term performance, it will be necessary to: 08/25/93 -67- ■ Integrate the wetlands into the golf course construction, ■ Oversee initial planting and start-up, and ■ Develop a Field Operations Manual based on the first two years experience. To accomplish the above requirements, the following operation and maintenance responsibilities will be adopted. 1. From Construction to 2 Years Later 1 All wetlands will be owned and operated by Lewis Homes. During this period, they will be planted, irrigated, and maintained by Lewis Homes. The experiences gained during this two-year period will allow the development of the Field Operations Manual. This Manual will describe the detailed operation, maintenance, i monitoring, and reporting requirements for the complex of water quality wetlands. A more detailed description of the content of the I Manual is contained in Section VII of this report. 2. After Two Years At the end of the two-year period, following completion of construction of the wetlands, they will be turned over to the SBCTFCD for operation, maintenance, monitoring, and reporting as a regional NPDES facility. The Field Operations Manual, explaining the recommended policies and procedures, will be provided to the SBCTFCD. This Manual will describe the role of the golf course operator in performing routine irrigation and I 08/25/93 -68- maintenance of the wetlands. Monitoring, reporting, and wetland renewal will he accomplished by the SBCTFCD. During the period when Lewis Homes operates and maintains the water quality wetlands, it will perform the water quality monitoring and wetland management practices described in Section VII. C. Sand Filter Infiltration Facilities The sand filter infiltration facilities are integral portions of the golf course. The surface of these facilities will he maintained by the golf course operator. The monitoring of the filters through the particle size analyses described in Section VII will be conducted by a certified soils laboratory in the presence of an inspector or engineer representing the SBCTFCD. Removal and replacement of filter material shall be done at the request of the SBCTFCD by the golf course operator in the presence of an inspector from the SBCTFCD. Should the golf course operator not comply with the SBCTFCD request for remedial work, the District shall, using its rights-of- way, perform the remedial work itself and assess the golf course owner. Records of all operation, maintenance, monitoring, and reporting shall be maintained by the SBCTFCD with copies provided to the City of Fontana and the Regional Water Quality Control Board. 08/25/93 -69- IX. ROLE AND RESPONSIBILITY OF THE DEVELOPER AND GOVERNMENT AGENCIES A development of a regional flood control and water quality facility involves not only the land developer but a number of government agencies. The following describes the responsibility of each. A. Lewis Homes Lewis Homes is the landowner and developer. As such, it will arrange for the design and phased construction of the flood control, drainage, water quality, and infiltration systems as part of its development for housing and commercial properties and a golf course. Lewis Homes will own and operate each phase of each facility until they are dedicated, or by agreement, transferred to another entity as described below: 1. Reinforced concrete boxes and channels to convey storm water in Summit Drive and downstream to the infiltration facilities - transferred to the SBCTFCD with adequate rights-of-way. 2. Surface swales for flood overflow within the golf course - transferred to golf course owner/operator with adequate rights-of-way to the golf course owner/operator and the SBCTFCD. In the event the golf course owner/operator fails to perform, the SBCTFCD will assume operation and maintenance responsibilities and assess the golf course owner/operator to recover its costs. 3. Local in -tract storm drains - transferred to the SBCTFCD with adequate rights-of-way. 08/25/93 -70- I 4. Water quality wetlands, after two-year start-up and availability of Field Operations Manual - transfer to the SBCTFCD for operation and maintenance as a regional element of the NPDES program with adequate rights-of-way Lewis Homes will maintain underlying rights to adjust or otherwise modify the wetlands as required for proper golf course management, provided such modifications are consistent with the NPDES program. Aesthetic maintenance of the wetlands will he performed by the golf course owner/operator with adequate rights-of-way. 5. Sand filter infiltration facilities- transferred for surface operation and aesthetic maintenance and sand filter remedial work by the golf course owner/operator with adequate rights-of-way. The SBCTFCD will he provided with adequate rights and rights-of-way to assure the proper operation, maintenance, and routine filter remedial work is accomplished by the golf course owner/operator per SBCTFCD requirements. 6. Spillway hardware; spillway, swales, etc. - transferred to golf course owner/operator. The SBCTFCD will be provided adequate rights and rights-of-way to assure proper maintenance and repair. B. City of Fontana The City of Fontana is responsible for approval of the Sierra Lakes project including the flood control drainage facilities. Additionally, under its role as a co -permittee with the SBCTFCD, the City will he responsible for the implementation of storm water runoff quality controls. 08/25/93 -71- The City will review and approve the flood control and drainage facilities and the complex of NPDES Best Management Practices (BMPs), which include the water quality wetlands and the sand filter infiltration system within the golf course. The City may choose to transfer the entire flood control system and the water quality facilities to the regional drainage agency which is the SBCTFCD for operation and maintenance as part of its regional system. If the City retains any of the facilities for operation and maintenance, it will be responsible for their monitoring, inspection, and operation and maintenance. C. San Bernardino County Transportation/Flood Control District The Lewis Homes proposal to develop a comprehensive regional plan for flood control, water conservation, and water quality management will have a significant affect on related regional responsibilities of the SBCTFCD. The groundwater recharge system, as proposed by Lewis Homes, will probably he implemented in other areas in the North Fontana area. This type of regional planning will alter the flood management and water quality requirements of downstream systems. It is proposed that the SBCTFCD will accept the Lewis Homes facilities as part of its flood control and water quality master plan. Once accepted, it is understood that it would accept the transfer of the facilities for operation and maintenance from the City. For this to happen, the District would need pre -approval of the concept and the plans and specifications. 08/25/93 -72- D. Golf Course Owner/Operator The golf course owner/operator will perform a number of very important functions related to this flood control and water quality management proposal. Due to the owner/operator's continuous presence in the management and operation of the golf course, lie will be responsible for the prevention of 1 unauthorized access to the golf course, the wetlands, and the recharge basins during storm times. The owner/operator will maintain the water quality wetlands and the surface of the rapid sand filter infiltration areas and will be responsible to respond to the SBCTFCD requirements for remedial work such as replacement of filter material if required. In summary, the golf course owner/operator will: N Maintain security and prevent trespass of golf course areas, particularly during storm periods; ■ Provide aesthetic maintenance of the water quality wetlands and the rapid sand filters; ■ Perform remedial work as required for sand filters and other drainage related facilities within the golf course areas; and ■ Cooperate with the City and SBCTFCD concerning monitoring or maintenance of all flood control and/or water quality facilities. 08/25/93 -73- X. LIABILITY The liability accepted by each of the firms and public agencies involved in the planning, design, approval process, and construction of the sand filter infiltration system is summarized as follows: Project Engineer - Errors and Omissions liability related to the planning and design of the facilities. Lewis Homes - responsibility for the construction per the approved plans and specifications. Golf Course Owner/Operator - responsible for any trespass or use of the golf course year-round including during times of ponding in recharge basin areas of the golf course and during times when ponded areas exist in the water quality wetlands. Also responsible for aesthetic aspects of all facilities within the golf course. City of Fontana - responsible for the effect of its approval of plans and specifications and for operation and maintenance of any facilities it accepts. SBCTFCD - responsible for the effect of its approval of plans and specifications and for operation and maintenance of any facilities it accepts. 08/25/93 -74- XI. PHASING OF CONSTRUCTION Lewis Homes recognizes that this proposal to create a regional flood control and water duality system, using sand filter infiltration facilities and wetlands, will take between 1 and 3 years to obtain the necessary permits and construct. During this time period, it will he necessary to phase the construction of these facilities to meet the following objectives: 1. There will not be any increase in flood peaks downstream of the Sierra Lakes project. 2. Interim BMPs will he used to prevent the degradation of surface runoff water quality. In addition, it will he necessary to develop a phasing plan for the development of any temporary or permanent facilities required upstream or downstream of the Sierra Lakes property. Sierra Lakes will prepare and receive approval from the City of Fontana and the SBCTFCD of a phasing plan for the construction of the flood control and water duality management facilities that will he up -dated, if necessary, every six months. 08/25/93 -75- XII. FINANCING OF CONSTRUCTION AND OPERATION, MAINTENANCE, MONITORING, AND REPORTING The construction, operation, and maintenance of flood control and water quality facilities that affect numerous properties are clearly regional in impact. As such, it is reasonable that the beneficiaries share the cost of the planning design, construction, and operation/maintenance of the facilities. It is common to establish Area Drainage Plan (ADP) fee systems to finance the construction of the facilities. Often a Benefit Assessment sub -zone or other mechanism is used to raise the required operation and maintenance funds. The ADP fees are charged to each developer in the "benefiting area" as they develop. The Benefit Assessment is typically levied on each residential or commercial unit in the benefiting area. The Lewis Homes proposal represents a major link in the regional flood control and water quality chain. The flood control, water conservation, and water quality benefits of the integrated concept extend far downstream. It is appropriate that the concept presented herein, once approved by the City of Fontana, be expanded to maximize its benefits throughout the North Fontana region. It is also appropriate that the City of Fontana act to establish the regional financial framework of ADPs and Benefit Assessments or equivalent financing so that Lewis Homes may recover that portion of its costs attributable to regional benefits for other lands. 08/25/93 -76- XIII. FIGURES 08/25/93 -77- San Gabriel Mountains zlpe-el� Duncan anyon Ro Summit v ti Curtis U Avenue d V\ n1 �1 rVC`i v Highland NTS 01 E CITY OF FONTANA venue R� E ow Ln r Walnut A wo CITY OF RIALTO {____ Proposed Freeway Avenue TAKEN FROM: SIERRA LAKES SPECIFIC PLAN PREPARED BY TURRINI & BRINK o � Q Summit v ti Curtis U Avenue d V\ n1 �1 rVC`i v Highland NTS 01 E CITY OF FONTANA venue R� E ow Ln r Walnut A wo CITY OF RIALTO {____ Proposed Freeway Avenue TAKEN FROM: SIERRA LAKES SPECIFIC PLAN PREPARED BY TURRINI & BRINK M M+ N"Pm m m m m m M M mo.m M M r ett• C= c S ttttl m= =1 O� PA as J fA J S^611 FIMJLI Ar A A Nd'.!FAVII l J A. 1 ' p 'A1 W V. Lql 7' Of .►�. �.► y " -� PA.3 1 a -, �^ .,•`, 4 -ililoo_ !'! _, , •SINGLE FAMIY ATTR[ H fA.1 1 1 � 1 .�.' •1•r�• 1, i � 1 �. 'A. 1A1 U1: I SINGLY FA1111Y '~ �� t • -� i rA'1 ♦ 'f DI•.Ai 21 SAL \ SINGLE fAMIU r n I17 DL•', 1 4C I u tS,y JJ '• i SJNJ:LF-FAXJCY 1 ` +.:DJ • ' `I I. MUAc I 6 �.� ' 9�D1 ♦< r f ` - •�'� :��z yam'- /1;`PA 'd N \ `\ . j� tet.•,• + t rA.t t� �t. ,:f� 3 .� J IS SJAY•LE FAMILY ':. T\+� ' '_•v `: PA. JJ ► jl SI 9 lC `, SU'Gl1 FAMILY / •? • I 1 t-: 12J DP : ' �'`�/ "..i ••� '� !f ; ACi✓ `• >: v ;t V• t� aof ` AA. IJ I.� F I i SINGLE � FAMILY bd AC 43 DU 1 - IIPA.M 1 SlMG1Y fAMlLI•A (i �'OADOYDYNYl1S1 144AC 173DU 12W. -AC �I of )76' rA. USINGLEFA.MILY ATTACKED 1TOWI99ADCNE Jet nu d !! DLNAC 6 4 s v - `- ' STMIIEfAMKYATLACHED `c, ` \ y► (DJJrfYILYIAC /YSFS) j 1 �V cs Jl f1 222DU 9 DUTAC ``' • *� s► ' rAn I 1 � 121AC PA. 2/ PA. is PA. 21 p HGil1G' J COXr01tATECEN It, - MR1'OXA2Z CEVlSR! 12 Ac (1 c z AC RETTAURAAT lOW XESTAUXAAT XOw ( ~ 9D AC--._ --- 1! -IAC `ice s1Nc[F AAMILY va � L fl DL'»lC ` a7j(� J --- - - - ----- wurwr_-__�__� _---_-_ r- __ J �- - - ---Irk-�-�------- -- - '--��-------- �' - -------------- r----------------------------------------- ----- -------------- �----------------------------------------------------------- AO SITE OF STORM WATER RECHARGE BASIN TAKEN FROM: SIERRA LAKES SPECIFIC PLAN PREPARED BY TURRINI $ BRINK a SIERRA LAKES DATE ❑ NTS %k. .d,oe.,�� CONCEPTUAL DEVELOPMENT ^8^ 93 A LITI n1�I11 I • r•��r n • �•. SUMMIT — AVENUE I. . . . . 15 5 4 - 13 ! 14 6 1 l 7 s 16 M 4 3 < I 8 ! i I i8 7 I .19 •8 9 11 � 20 t M 3 2 10 I I I 10 MIUMLANU AVLNUL INDICATES PERCOLATION TEST N INDICATES OBSERVATION HOLE 6:) INDICATES EXISTING STRUCTURE PLOT PLAN LA M X D NOT TO SCALE TAKEN FROM: RMA GROUP'S PERCOLATION TEST RESULTS REPORT (NOV. 8,198 `1 I OUTLET SWALE STORM DRAIN PIPE DIVERSION STRUCTURE FIRST FLUSH DIVERSION PPE UNDERGROUND LIMITS OF INFILTRATION AREA WATER QUALITY WETLAND - 1 � WATER QUALITY WETLAND AND SAND PERCOLATION BED TYPICAL PLAN N.T.S. CATCH BASIN STORM DRAIN PIPE DIVERSION STRUCTURE-/ FIRST FLUSH DIVERSION PIPE --� TO WATER QUALITY WETLAND A SURFACE LIMITS OF SAND FILTER AREA WATER DUALITY WETLAND �-- MAXIMUM WATER SURFACE ELEVATION SECTION A -A N.T.S SU,PFACE C IA17ITS OF $,4it/O F/C TER AREA _ CR6'ROUNO L 111WTS OF /�t/F/C T,PAT/ON A,QEA �% NT.s TUQFEO GOOF clouRrF S'UOGR.QOE SO/G F/CTE,E' FAB,PiC C /ic/�it/G 30"TWICK 6,124122,c -11 -7 -Fe F/C TER F/4BR/C C /N/NG O(/E,P GPA(/FG L,ovice /B'�Tli/CK G,P,9v�C CAS�FR 7-001OVI SECT/OA/ A -A Io'srAFF GAUE. TOP of CUr TEST PIT T PLAN N.T.S. �/O' STAGE GAUGE N,QTU 44 GROUND /O M14. U/SQUEEN�Z L,- ?vc ' V, 27, S,9it/O ,BAG (EFFECT/VE i2R6I7) TEST PIT 6U9GR,40E SECTION A -A N.T.S. srA,eEs 9CT ,QkUW22 TEST P/T SUB60�Z2E OFTA/L 'A'/ �-/9E'P/METEe FRAME /O M/z u/5Qv�2v (2 LAYE.PSI 1.25/ 5',Qit/D/'�Il w�lI_�l DETAIL "A' N.T.S. 12 Ell w D Q m 0 m^ co w LLJ OL Q Z Lu 10. C) QW Y 2 SIERRA LAKES S INFILTRATION TEST RESULT __. 2 , .,C1 MA-rC= nF INFILTRATION V 0 10 20 INFILTRATION RATE ( FEET PER DAY ) 0.156 0.208 0.260 0 0.052 0.104 INFILTRATION RATE ( CPM PER SQUARE FOOT ) 'Com tA TE1TfMER & A550CY+rt=i um enomeeRlnG MAMAQEHEt1T Ptnr+rn 5151 Agway Avenue. 5ude Q1 Coasta Hera, Caldorn�a 926266 61 0.313 SIERRA LAKES INFILTRATION TEST RESULTS DEPTH VS. RATE OF INFILTRATION TEST PROGRAM N0.1 DAT E 8-93 FIGURE 7 3 4 u 3 Q L �^ O 3 a 4 4 J t J4 /Z /O 8 6 4 2 O 0/97,i2AI'E F,POM li/SQC/E�N EDGE 4./' - 8 CFEET) � TEST PIT —G � ELEI/. Inti PROP If /22 ,O 2 — Z B G ¢ 0 0 2 —O 3 4 9 8 T &LL S , , EQU/POTENT/qL C /NES FLO(,✓ C/NES�TS�i�/CAL% (T �P/CAS) SIERRA LAKES DATE 8-93 INFILTRATION TEST RESULTS .conn n T rrEmER a A55"T i Lm FLOW NET ANALYSIS FIGURE EMiNtENNO MAWtMCnT PLAMT11ti s TEST PROGRAM NO. 1 8 3151 Airway Avenue. 5uite Q•1 Costa Mesa, Californ a 92626 i �— — — L/All/T OF a � V /O "57/AFF GOUGE- Too AUGEToo OF OUT TEST PIT "I" PLAN N.T.S. /0' STAFF GAUGE SPD/L P/C E /NATURAL GPOU�t/O 25' V/SQUEEN CZ Cl�y��FS') 27 F/L 7-62 F,ga,210 /8"i///CK GRAVEL SECTION A -A N.T.S. SIERRA LAKES DATE B-93 TEST PROGRAM NO. 2 FIGURE JOHN M T"MER & A550CIATt3. LTQ En61MCPLAN AND SECTION 9 MINC) rw1A43tmENT PLAf1111t1G 3151 Airway Avenue. 5wte Q1 Costa Mesa, California 92626 SIERRA LAKES INFILTRATION TEST RESULTS DEPTH VS. RATE OF INFILTRATION 2 X0. 12 / 10 m o w 8 SUBGRADE 0 �O• m c� m m 6 � 6 0 z Q — wv _) J Q m 4 FILTER, FABRIC (MIR FI 140 N) 2 GRAVE SURFACE TES NO. 2: FILTE FABRIC (MIR Fl 140 N) OVER 0160 18" OF RAVEL(1"-1 STONES) 1/2- 0 0 10 20 30 40 50 60 INFILTRATION RATE ( FEET PER DAY ) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( G.PJA PER SQUARE FOOT) SIERRA LAKES DATE 8-93 INFILTRATION TEST RESULTS DEPTH VS. RATE OF INFILTRATION FIGURE �� conn n TtTfl=h1ER & AssocwT�, LTD En61nEERIN(a MAnAQCMfnT PLANNInG TEST PROGRAM NOS. 1 AND 2 10 3151 airway Avenue. 5uite Q-1 Costa Mesa, California 92626 2 X0. / SUBGRADE SIERRA LAKES PER CENT COARSER BY WEIGHT PERCENT PASSING IIIIIIIIIIIIIIIIIIIIillllllllllllllllll NIIIII „ IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII oil �III1111 , ,1111111111N1111111111111N1111� 1111N1111111111 , ; n■■t■t■t■tttt■t■■tt■■t■tt „ - ■■■/■ttt/tttt/tt■■ •„ liiiiliiliiiiii■iiiii■ilii ■■■Ni�iiiiiiiiiii.,, 10 ..ii.....i..r.....i....... ...�....�......... , IIIIIIIIIIIIIIIIINIIIIIII. 10 _II�IIIIIIIIIIIII "•NM11111111111 ; ,11111111111111111111111111. • min 1111111111 :1N11111111111111111111111 - . Illllllllllllllll 111111 �nn1�1111��1moll 1111111111 IN „ ►111111111ni1I11111111 IllllNlNllllllilllllllllll�lln��lllll�!����ii!i; . INni_II.111!111!111111111111�!�!Illlillllllllllil: !i oil '�11111111111i111111111111m11i111111111111111N1 X1111111111111111111111111111-111111111111111111 . 111111�11111111111111111111�1 111111111111111111 lllllllllllllllllullllllllll' 1111111111111111111 .■■■■■.■.....■.....■■u■■■■■■ .............■■.... Illllllllllllllill 1111111111.111111111111111111 ; • = 11111111111111111111111111111 11111N11111111111 ; - 1n11111111111111111111111111 111111111111111111_ , , .11111111111111111111111111111111111111111111111111 .. Illlllllllllllllllllllllllllllllllllllllllllllllli „ PERCENT PASSING SIERRA LAKES LABORATORY FLOW TEST RESULTS Sand Sample: #12 Silica Sand Sample Length: 6 inches Sample Diameter: 2.5 inches, Area = 0.0341 ft2 Sample Permeability: 0.36 ft/min Darcy's Equation: Q = kiA Discharge vs. Headloss Calculation h I h I A,ft2 0.50 0.50 1.00 0.0341 0.60 0.50 1.20 0.0341 0.80 0.50 1.60 0.0341 1.00 0.50 2.00 0.0341 Q/A K ftmin ft3 min m ft2 0.36 0.0123 2.70 0.36 0.0147 3.24 0.36 0.0196 4.32 0.36 0.0246 5.40 SIERRA LAKES INFILTRATION TEST RESULTS Computation of Test Pit Flow Rates Test Program No. 3 #12 Silica Sand k = 0.36 ft/min Total Available Head, ft Sand Filter Headloss ft Subgrade Available Head, ft Subgrade InfiIt. Rate,") ftLday gpm/ft2 Maximum Subgrade Inflow, (21 gpm Sand Filter Face Vel."), gpm/ft2 Sand Filter Area Req'd ft2 Dimension Sand Filter Infilt, gpm 10 2.5 7.5 32/0.167 121 2.70 81/9' 219 10 1.57 8.43 38.4/0.201 146 1.70 81/9' 139 1.0 'I <f7 8:33 37.710,'196 143 1,80 619' 146 8 x::20 6;8 26.8/0:140 102 1:30 8119' 105 6 0.79 5.2 15.5/0.081 59 0.85 81/9' 69 6 0.65 5.4 16.8/0.088 64 0.70 81/9' 57 6 0.74 5.26 16.0/0.083 61 0.80 81/9' 65 1? 0.69 5:31 `i 6.3/0:085 62 0.75 $ i. .' 61 8 0;46 4.54 10:8/0.056 41 0.50 81/9, 41 Notes: (1) From Test Program No. 2 measured data (2) Based on effective infiltration area = 729 ft' (3) At bottom of sand filter TEST PIT 'I' PLAN N.T.S. , 42TER S'UPCY r -OP OF SCOPE �Ait/D F// -TER AREA ?xq' /O `STAFF GAUGE TOP OF Cur „0 ,ovc 6 "o Pvc SAND I& The SECTION A -A N.T.S. /8 " G,P,QvCZ DETAIL 'B' N.T.S P/EZOt//ETE-R MAT/(/E MAIC el,1Z F/C Tf�P F�B�P/C SIERRA LAKES INFILTRATION TEST RESULTS DEPTH VS. RATE OF INFILTRATION 8 12 LU U U_ 6 10 p W Z w Q LL 04 p8 Q w0. t7 4 m LL Z O O =2 �6 w p U Q SAND SURFACE 0 �4 \�� 2 FILTER FAB IC (MIRAFI 14 N) OVER 18' OF GR (1"-1 1/2" ES) 0 0 10 20 30 40 50 60 INFILTRATION RATE ( FEET PER DAY ) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( G.PM PER SQUARE FOOT ) SIERRA LAKES DATE 8-93 ® INFILTRATION TEST RESULTS �. .ctias.as� DEPTH VS. RATE OF INFILTRATION FIGURE "I'l M TUT51'IM & A55"TC� LTri ft —' MOINEMM(3 MAA6EMENT rLANNIMs TEST PROGRAM NOS. 1,2, AND 3 15 5151 Auwav Avenue. Suite Q-1 Costa Mesa, California 92626 3 o TEST NO. 3: 30"OF 0.12 SILICA D FILTER AERIC (MIRA l 140 ) SUBGR E a h TEST PIT "I" PLAN N.T.S. WTE,e SUPP� v 2P OF SCOPE /0'STAFF GAUGE TOP OF CUT 0 /'(/C SECT] ON A - A N.T.S. 6 "o Pvc STAFF GAUGE U/SQUEEiV- SAiUD F/L TEMP l2 C,QS�E,PS� q DETAIL 'B' N.T.S P/EZOMETE.� F/C TE,P F,-22B.P/C SIERRA LAKES INFILTRATION" TEST RESULTS DEPTH VS. RATE OF INFILTRATION 8 12 w U L 6 10 �G c_ �O• p z ►- w ¢ c/) w LL �O• w8 z4 O Q 18' OF GRA EL (1"-1 1/2' ONES) w 0 �O' SU RADE LL 02 Q 6 = Q Lu SA D SURFACE w U y 7 1�1 4.5' TH1 F SILT < L 4 p P TEST O. 3: 30"OF 0.12 SILICA D FILTER FABRIC (MIRA 1140 N) 2 FILTER FAB IC (MIRAFI 1 0 N) OVER 0 0 10 20 30 40 50 60 INFILTRATION RATE (FEET PER DAY ) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( G.PM PER SQUARE FOOT ) SIERRA LAKES DATE INFILTRATION TEST RESULTS 8-93 DEPT H VS. RATE OF INFILTRATION FIGURE _ JOf'Ih M TETTff1Eft &ASSOCIATES LTD — t'FJlNEEfilt76 MAPA(MmtYT Ft"NlrtQ TEST PROGRAM NOS. 3, j7 5151 Airway Avenue. Suite Q1 California 92626 Mesa. Californ92626 4 A, 4B, AND 4C 18' OF GRA EL (1"-1 1/2' ONES) SU RADE a SIERRA LAKES INFILTRATION TEST RESULTS w w 0 0 N nw z= a� WU c� z _ �N U z � a a. N Lij U *e- a cr- 0 El � z a 6 Q 0 O 12 J W m 18 LU 0 24 30 0 1 2 3 4 5 10 15 PER CENT PASSING THE 200 SIEVE DEPTH OF SILTED SAND REMOVED AND REPLACED FOR TEST PROGRAM NO. 5 SIERRA LAKES DATE INFILTRATION TEST RESULTS 8-93 J N M TMtMM & A55CGAT� LTD. ` = tncsinttr�nc MArwatMtnr P' AN"NC SILT MIGRATION DATA FIGURE 18 3151 Airway Avenue, 5uite Q-1 Co5ta Mesa Caiiforma 92626 a a h TEST PIT 'I' PLAN N.T.S. it I W7C,,P 6UPPCY )P OF SLOPE PAID F/L r6e ,-W&V 'x q' /0 '57AA-F GAUGE TOP OF our 4 P(/C SECTION A -A N.T.S. 6 "0 PVC STAFF GAUGE l//SQUEEN- SAND /&7-62 �Z C,QS�E,PS> _w PEPCl�CED i SAND /O'J FPON/E5' !8 " 6;e27VEL DETAIL "B' N.T.S P/EZor�ErE,� /UGIT/(/E MA7CP/,41- � F/C TEB F�B�P/C SIERRA LAKES INFILTRATION" TEST RESULTS DEPTH VS. RATE OF INFILTRATION 8 12 w U LL 6 10 r� tk o w z w a LL `n w 0. 04 Q 8 0 w m Q � �zz U- 0 2 -02 6 F w CL _ w U o � Q SA C 0 > 4 2 2 0 0 10 20 30 40 50 60 INFILTRATION RATE ( FEET PER DAY ) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( G.PM PER SQUARE FOOT ) SIERRA LAKES DATE 8-93 INFILTRATION TEST RESULTS DEPTH VS. RATE OF INFILTRATION FIGURE Donn M MER & A550CWTE� 1 2 0 ENOINEER N13 MAftAQEMEnT PLMNINQ TEST PROGRAM NOS. 3 AND 5 5151 Airway Avenue 5uite Q-1 Costa Mesa, California 92626 G � o / SA D SURFACE NEW D (10') REMAINI G ORIGINAL (20') FILTER AERIC (MIRA 114 N FILTER FABRIC (MIRAF 140 N) OVER 18 OF GRAVEL ( -1 1/2' STONES) SUB ADE a �I TEST PIT "I" PLAN N.T.S. ATE,P BUPPCY 2100 F S[OPE 4A/D F/[ TER P,eF-q k 9' /O'S'TAFF GAUGE TOP OF CUT 0 PVC c c, v c , —I c. AW iUAT/vC 412W2C.P1A1- �- F/CTEe FAB.P/C SECTION A -A N.T.S. C ,of Pvc STAFF GOUGE l//SQUECAI (2 L,QYC,PS) NE�,P SU,PF lwrll/C 9M- 670ra 30'' F,Pl�MES �• sA�vo /ON l8 " 6;eO /CZ i 011 DETAIL "B" N.T.S c c, v c , —I c. AW iUAT/vC 412W2C.P1A1- �- F/CTEe FAB.P/C SIERRA LAKES INFILTRATION' TEST RESULTS DEPTH VS. RATE OF INFILTRATION 8 12 w U 30' OF NATIVE MATE FILTER AL AERIC (MIRA i ' 1140 W � LL 6 10 FILTER AERIC (MIRA 1140 N) OVE / RAVEL (1'-1 2' STONES) g o w SUBGRADE < LL 8 O 4 U OC ¢ Ir co O Li H 0 m ¢ 0ZZ LL O O O 2— �6 ~ Uj w w _ � U 3 SAND SURFACE r SOD �4 0 2 2 0 0 10 20 30 40 50 60 I INFILTRATION RATE ( FEET PER DAY ) I 1 1 1 1 1 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( G.PJA PER SQUARE FOOT ) SIERRA LAKES DATE ,�®� B-93 INFILTRATION TEST RESULTS 7� DEPTH VS. RATE OF INFILTRATION FIGURE LTD TEST PROGRAM NOS. 3 AND 6 - _— BEmtriT iQlNfC N13 MAMEMER PLANNIrIATE5, en�ineeAma nArw�eMenT r�Anronc, 22 5151 Airway Avenue. 5w[e Q-1 Co5ca Mesa, California 92626 30' OF NATIVE MATE FILTER AL AERIC (MIRA i ' 1140 W � FILTER AERIC (MIRA 1140 N) OVE 18" OF RAVEL (1'-1 2' STONES) SUBGRADE LL m 0 z 4 m w u- 2 O 2 n. w 0 0 SIERRA LAKES RECOMMENDED DESIGN INFILTRATION RATE CURVE LOCATION I 12 DEPTH VS. RATE OF INFILTRATION p w Lu w10 w 0 ¢ m 0 m m z8 O Qo W U J W. • 1.2 2 0 0 10 20 30 40 50 60 INFILTRATION RATE ( FEET PER DAY) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( GLPJA PER SQUARE FOOT ) FDR 00AIPYA10 PEPT/15 ABOUE G ET OPV 7W6- SAND 9662Fl20E USE �5. S FT/PAY 3,x.3 24.8 14.8 /Z.5 10.5 SAND SURFACE 90 "6,1%4/0 F/L TEMP F/L TFk' F salt LAYER SUBGRAD SUQFACE 0 0 10 20 30 40 50 60 INFILTRATION RATE ( FEET PER DAY) 0 0.052 0.104 0.156 0.208 0.260 0.313 INFILTRATION RATE ( GLPJA PER SQUARE FOOT ) TEMPORARY DEBRIS CONTROL FACILITY —MgtrpO rr StC�O G7O ® t= r-- Mgt 0"". r,, 1 nf`G'.EfUrfu r®..""..•y �. .�.� �" , `LIQ rAER lJ.1GLE rwwN,r 4 A• I Ra S w1 li' FAxfLI ArT41 H. rs, / `• !f 1 _ r •3� `' - - 4...�• . al r. 1 •�. ►A 1�� ' f hl tai rA 1 ., \ l� Sfvfi7L fAXfLI SINfifaxlL-y� ` - rA - r— Wilt '. 1 S/M:LE fAYI14. i� I #7 It •• a.l ,.V ' /'k, ;r:�'"-'-.� .40' ', II.Al 'I 1 I , >' _ I , j•i Sit', IE fANJtI' ,,• t SIA ME 'GLE iWflJ• 1 f'LII l : AC• 1 �: iiia. 1 •` \ .t. 1ane fcx _�aPA. 12 J3_6 0 AC SINGLE FAYl11•671 • rE ' _ I ' ' f ' 1 1icLs i:• �I /t ul�cLEFAMILY ♦ I IFAMI j i I J r !, 1I1 �s�ne `a� �♦ r�.,.\`�f,,' ,1.�r.-A..,n f�`+����� //I.°I n>7 -;I,� ! f���f�it;'k�\+�a DU f SINGLE i ATTACXW L�w TOMNN09ES l '4 t 25uFLO; . n 14 AC i i 2:nv:Ac I 1 ` 1>'AAC Gr' `� • '-• t oSfNGLE FAMILY ? �4°'f /i ! : �� $ i 94DC �§ `a1,f: fASING FAMILY AA. 17 L, .22 �IItIFFAMILY • IhG(E FAM1L1+1 9d AC '�.'��� ATTACHED y� i I a �� i✓♦ yj1Q r If OLaHOYAC 80 DI, EsrI 1 10, r+/ I L� .4 ,.�~-•�•i"!" ., If OC7AC +1 i I I INGLE FAMILY 1: "/.' ' PA. 29 `♦ ATFACHED 1 NNXOMt1S1 1 �Sl.YGLE F"LLY FTAC1sED I♦ 1f9AC �r. PA. - /"" \f\7.� *uo i `•1. i 'Oh90M4Y/Ux/TCNNXOX6 la Dl Q / D SINGLE •+b _ 1 IIAC 10 ' II DWAC12 DV;AC 7 FAMILY I l i1 DU JI IN P.A. Jf may. I ur I Es w I • ~� i I �r 24.7 222 DC .44 1 9DUTAC1 1 rA 2J I 1 25 JAC LA'r I I rE AC 1'.A.,U I i j rA.7f rA is /US/NCSS rAlK O CltrY1RATE CENTER' S? RRAAACTROr / V 9.2 AC R$SFAC+RMT!<OW 14.l AC 9DAC r 1— ----- � r -'. r LEGEND OFF-SITE DRAINAGE COLLECTOR CONDUITS ON-SITE IN -TRACT DRAINAGE CONDUIT WITH WATER QUALITY WETLAND AT OUTLET TEMPORARY DEBRIS CONTROL FACILITY TAKEN FROM: SIERRA LAKES SPECIFIC PLAN PREPARED BY TURRINI & BRINK SIERRA LAKES DATE a _ 8-93 ❑ NTS � �• -�«�w- PROPOSED OFF—SITE AND FIGURE ON—SITE ia'"nr"e�&assaw'u`M DRAINAGE FACILITIES 24 enl31MCERIMG MAM MMEMT "HNInci 5151 Alrwav Avenue. 5ufte Q-1 Costa Mesa. Californ,a 92626 SAND FILTER SAMPLING LOCATIONS (TYPICAL) TYPICAL SAND FILTER WASTE AREAS �rq % S°' o. so. o. o. PLAN VIEW N.T.S. SIERRA LAKES DATE 8-93 TYPICAL RAPID SAND FILTER FIGURE e=Jorm'ATETrEMM&A550CIATMLM TESTING LOCATIONS Efuto fvuworMtM FLAM IMG 25 5151 Arway Avenue, Suite Q 1 Costa me3a, California 92626 XIV. PHOTOGRAPHS 08/25/93 -78- • q � i C r�, 00 � 5 t' � f Gig i 250 1 7 t1 � N v GALLONS Photograph No. l: 3 -inch flow meter with totalizer dials. *� I Photograph No. 3: 6 -inch pump discharge line from pump to test pit. wr .j Photograph No. 2: 3 -inch and 6 -inch flow meters plumbed into 6 -inch discharge line. 1 . wr .j Photograph No. 2: 3 -inch and 6 -inch flow meters plumbed into 6 -inch discharge line. Photograph No. 4: Test Program No. 1, placing of visqueen liner. T - Kit;' 1 1 Photograph No. 5: Test Program No. 1, completed test pit. Photograph No. 6: Test Program No. 1 testing in progress. g P g , g P gress. Photograph No. 7: Test Program No. 1, near completion of Test No. 1. y • d;; •. � „}� irk` _ { Photograph No. 8: Test Program No. 1, examining side slope for seepage after completion of Test No. 1. z , ` �•� _ .,ice Photograph No. 9: Test Program No. 2, material used for 18 -inch thick gravel layer. Photograph No. 10: Test Program No. 2, placing 18 -inch thick gravel layer. iii r{ .� Photograph No. 11: Test Program No. 2, beginning of testing. Photograph No. 12: Test Program No. 2, near completion of Test No. 2. i. A_i7' 1 _ `-� � ,i -, .+. - .� - u• :; � � 3./ Ari �.'� I�S` ,�T Photograph No. 13: Test Program No. 3, placing backfill adjacent to 9 -foot square sand filter frame. Photograph No. 14: Test Program No. 3, installing 6 -inch perforated PVC pipe. gid' ��� _ r ..•mar_--- -� i Photograph No. 14: Test Program No. 3, installing 6 -inch perforated PVC pipe. gid' ��� _ r ..•mar_--- -� % r Photograph No. 15: Test Program No. 3, placing No. 12 silica sand filter material. F�f mss. Photograph No. 16: Test Program No. 3, near completion of Test No. 3 r , % r Photograph No. 15: Test Program No. 3, placing No. 12 silica sand filter material. F�f mss. Photograph No. 16: Test Program No. 3, near completion of Test No. 3 NON `a` r •S Photograph No. 17: Test Program No. 4, completed test pit with 1.5 inches of silt over silica sand (Test 4A). J alLi Photograph No. 18: Test Program No. 4, near completion of Test 4A. Photograph No. 19: Test Program No. 4, taking 6 -inch drive samples of sand filter after Test 4A. ` < r'vie CN Photograph No. 20: Test Program No. 4, backfilling drive sample locations. s� r' �j It Photograph No. 21: Test Program No. 5, removing silted silica filter sand. Photograph No. 23: Test Program No. 5, replacing silted silica sand with clean material. s • "� -�, - � y a .��s mal Photograph No. 22: Test Program No. 5, close-up of silted silica sand filter showing clean sand at 8 -inch to 10 -inch depth. SIERRA LAKES TEST PROGRAM NO. 5 'VeJOHN M TFrT MER & A550CIATM LTD. NGINC[RIM0 MAWEM[NT PLANNING 5151 Airway Avenue. 5urte Q -I Costa Mew- California 92626 DATE 8-93 PAGE 6 4`-_ 4 - •",tip-•� It .� � _ •: "`� tee. . 1 �� �. ,, rs : • ..� . • ,�, - t' _ - - 4 _ - .ter.. _ _._� _•.1. Wr ....._tel. "`,• .—�.- -�___ _ _t _ .. _ _ � -•�_. __ - _ _ - �_. .r._.. .. _; i -;aA Photograph No. 24: Test Program No. 6, placing native material Photograph No. 26: Test Program No. 6, completed test pit. backfill prior to placing turf. Photograph No. 25: Test Program No. 6, completing placement of native soils prior to placing turf. Photograph No. 27: Test Program No. 6, testing in progress. XV. APPENDICES (under separate cover) 08/25/93 -79- l 1 1