April 17, 2026
Steve Leathers, PE
Vice President
Reyes Construction Inc.
1383 Signal Drive
Pomona, Ca 91766
Subject: Amendment No. 4 – Proposal for Additional Services
This amendment documents additional services completed that fall outside the original DBIA 540 scope for the Hermosillo Park Improvements project. These items were initiated by the Owner after construction activities had already begun, requiring new design work, revisions to approved plans, and coordination with in -progress construction. These tasks were not included in the original scope or fee.
ADDED SCOPE SUMMARY
1. Meetings and Concepts
To support the addition of the new recreation facilities, including the handball courts, basketball court, MUSCO sports lighting, and the conversion of the soccer field from synthetic turf to natural grass, additional meetings, coordination sessions, and concept level planning will be required. This scope includes participation in meetings with the City, the contractor, MUSCO, and other project stakeholders to review proposed improvements, discuss design constraints, evaluate alternatives, and confirm Owner direction before moving into detailed design. Concept plans will be developed to illustrate proposed layouts, grading strategies, access connections, barrier wall impacts, storm drain conflicts, lighting integration, and overall site interactions resulting from the revised improvements.
Work will include preparation of preliminary renderings, concept level grading exhibits, utility conflict diagrams, and preliminary drainage strategies needed to validate the feasibility of the proposed additions and modifications. These concept documents will identify key design decisions, constraints, and coordination items, and will serve as the basis for advancing into final design. Additional coordination will be provided to ensure these concepts align with improvements already under construction and reduce potential rework during implementation.
Deliverables for this scope will include meeting agendas and notes, concept exhibits for each revised site element, preliminary grading and utility sketches, conceptual layout options, and technical memoranda summarizing design assumptions and recommendations.
2. Addition of Handball Courts
The City directed the addition of new handball courts after construction had already commenced. This requires preparation of new design plans, including court layout, grading modifications, surfacing specifications, accessibility connections, and integration of the new facilities with the existing improvements currently under construction. The handball court improvements include the engineering and design of new structural play -walls, which function as free-standing athletic impact surfaces and are not associated with site-retaining conditions.
April 17, 2026
Work will include complete structural design and calculations for the handball court walls, including determination of wall height and geometry, thickness, reinforcement (bar sizing, spacing, splice criteria, and development lengths), and foundation system design. Design will address all applicable loading conditions such as player impact forces, out-of-plane and in-plane lateral loads, wind loads, and seismic demands per current code requirements. Wall designs will comply with the California Building Code (CBC), ASCE 7 load provisions, ACI 318 concrete design requirements, and, if masonry construction is selected, TMS 402/602 standards.
Additional design considerations include crack control, durability and surface finish standards required for athletic play, temperature and shrinkage reinforcement, coordination of wall/pavement interface conditions, and detailing for long -term structural performance.
Deliverables will consist of signed and stamped structural calculations, wall plan and elevation sheets, sections and details, and a concise design -criteria summary memo. Coordination will also be provided to ensure proper court dimensions, safety clearances, surfacing transitions, and integration with site utilities, grading, and drainage.
3. Addition of Basketball Courts
A new basketball court facility will be added to the project at the direction of the City. This work will require preparation of complete design plans for the court, including full layout development, grading modifications needed to achieve proper slopes and drainage, surfacing specifications, clearances for safe play, and accessibility compliance in accordance with current standards.
The new court must also be integrated with adjacent improvements already constructed or underway, requi ring coordination related to grading tie ‑ins, pedestrian circulation, drainage paths, and utility considerations.
The City has also selected specialty decorative basketball poles and hoop assemblies, many of which utilize precast structural bases or requi re engineered foundation systems. As part of this added scope, full structural design and calculations will be prepared for the hoop foundations.
This includes verification of manufacturer load data; evaluation of overturning, lateral forces, uplift, and dynamic player ‑impact loads; determination of footing size, embedment depth, and anchorage configuration; and specification of reinforcement including bar sizes, spacing, lap lengths, and development requirements. Foundations will be designed to resist wind and seismic loading consistent with current code requirements, including the California Building Code (CBC), ASCE 7 load criteria, and ACI 318 provisions for concrete design.
Additional design considerations will include compatibility with the selected surfacing and subbase systems, proper slab ‑to‑foundation interface detailing, durability, protection against potential cracking at pole bases, and clearances required for safe play and long ‑term performance. Deliverables associated with this added scope will include signed and stamped structural calculations, plan and elevation views of the court and hoop systems, sections and construction details, and a concise design ‑criteria summary memo. Coordination will also be provided to ensure proper alignment, drainage consistency, surfacing transitions, and integration with site utilities and grading.
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4. Storm Drain Relocation
The proposed location of the new basketball court conflicts with an existing storm drain alignment that had already been coordinated for construction. To accommodate the new court and avoid construction conflicts, the storm drain will need to be redesigned and relocated. This will require development of a revised horizontal and vertical alignment that maintains hydraulic performance while shifting the system outside of the new court footprint and ensuring proper clearances from existing and proposed utilities.
As part of the redesign, new hydraulic evaluations will be prepared to confirm adequate capacity, flow depth, velocity, and system performance under existing and proposed conditions.
Updated plan and profile sheets will be developed showing the revised pipeline alignment, slopes, structure adjustments, utility crossings, and connection points. Grading revisions will also be required to preserve positive drainage patterns and ensure that surface runoff continues to convey properly to the downstream system. Where necessary, modifications to drop inlets, junction structures, laterals, and access points will be incorporated into the updated design.
In addition, the relocation of the storm drain requires updates to the project’s Low Impact Development (LID) Report. These revisions will address changes in drainage management areas (DMAs), hydrologic connections, tributary flows, and required best management practices (BMPs). Calculations will be updated to reflect any change in impervious areas, reconfigured drainage patterns, or impacts to approved LID facilities. Narrative sections of the LID Report will be revised to document the updated drainage routing, BMP sizing, pretreatment requirements, and compliance with current municipal separate storm sewer system (MS4) permit requirements.
Corresponding updates to the Drainage Report will also be required. These updates will reflect the revised storm drain alignment, updated hydrology, and new hydraulic calculations. All supporting figures —including drainage area maps, flow paths, hydrologic basins, and runoff coefficients—will be revised to remain consistent with the redesigned court layout and storm drain system modifications. Updated tables, calculation summaries, and narrative sections will be provided to document the revised drainage performance and confirm compliance with City standards.
Additional coordination efforts will include field verification of existing site utilities, coordination with the contractor to avoid conflicts with ongoing construction, and evaluation of impacts to adjacent improvements such as pavement, walkways, landscaping, and other utility systems.
Deliverables will include revised civil design plans, updated hydraulic and hydrologic calculations, updated LID and Drainage Reports, and construction details necessary to implement the relocated storm drain system.
5. Irrigation System Redesign and Landscape Revisions
The City requested changes to the planting approach, including the use of larger tree species and adjustments to planting locations. These updates require substantial revisions to the irrigation system, including modifications to irrigation mainlines, lateral lines, valve zones, controller programming, and overall system layout to support the updated landscape requirements. Because work in these areas has already begun or been coordinated for construction, the redesign must be integrated with installed or in -progress systems to maintain compatibility and avoid rework.
April 17, 2026
The introduction of the new handball courts and basketball courts —both of which replace previously grassed areas—further impacts the irrigation system. Existing irrigation infrastructure in these locations will need to be demolished, abandoned, or rerouted to accommodate the new hardscape footprints. Revisions will include relocating or capping existing irrigation lines, redesigning valve groupings to reflect reduced irrigated turf areas, and rebalancing flow demands across the system. Where existing irrigation service lines conflict with new court foundations, pavements, or drainage improvements, the system will be realigned to ensure proper coverage of the remaining landscaped areas without creating overspray onto hardscape or public-use surfaces.
The redesign will also address irrigation needs for the larger tree varieties, including increased water demand, deeper rooting profiles, and expanded irrigation zones. Updates may include larger-capacity drip systems, revised emitter spacing, modified pressure -regulating devices, updated control valves, and adjustments to mainline sizing where necessary to maintain adequate pressure and flow. Newly adjusted tree locations will be coordinated with utilities, lighting, play areas, paving, and the newly added recreation courts to avoid conflicts and ensure adequate clearances for long-term tree health and site functionality.
Landscape revisions will include updated planting plans, revised plant palettes (to reflect the larger tree species and any associated understory plant changes), expanded tree wells, mulch areas, and root -barrier locations as required. Coordination will be provided to ensure proper integration with grading, drainage, hardscape edges, and adjacent improvements.
6. Playground Redesign and Expansion
The City requested revisions to the playground area, including expansion of the overall playground footprint and removal of the previously planned soccer ‑style playground equipment.
These changes require a comprehensive redesign of the playground layout, grading, surfacing limits, drainage pathways, accessibility routes, and equipment configuration. Because much of the work in this area has already begun or been coordinated for construction, the redesign must be integrated with improvements currently installed or underway.
The updated design will include reconfiguration of the play equipment zones, fall ‑protection surfacing areas, and associated safety clea rances to comply with current standards. Grading modifications will be required to achieve proper slope transitions, maintain accessible routes, and ensure positive drainage away from the equipment zones and toward approved collection points. Drainage improvements may also involve adjustments to inlets, subdrain systems, or adjacent landscape areas to preserve system functionality under the revised layout.
The redesign will also require updates to playground accessibility components, including ADA‑compliant routes, landings, ramps, and surfacing transitions. Revised equipment placement and surfacing boundaries will be coordinated with adjacent concrete, paving, walls, utilities, and landscaping to ensure compatibility with ongoing site work. Where applicable, structural anchorage requirements for new equipment will be updated to reflect manufacturer specifications and current code criteria.
Deliverables for this added scope will include updated playground layout plans, revised grading and drainage sheets, modifications to accessibility routes, updated surfacing limits, new equipment plans and details, and all related construction documentation. Coordination will be April 17, 2026
provided with the contractor to integrate the revised playground improvements with in ‑progress construction and to minimize rework or disruption to adjacent completed elements.
7. MUSCO Lighting
The new handball and basketball courts will require the addition of MUSCO sports lighting to provide adequate illumination consistent with the exist ing MUSCO system currently installed for the soccer fields. This added scope includes coordination with MUSCO to integrate their lighting equipment, confirmation of fixture selections compatible with the new court layouts, and preparation of updated photometric evaluations. Work will include developing lighting plans, identifying pole locations and mounting heights, designing conduit and power routing, and integrating the new lighting system with existing electrical infrastructure serving the park.
Structural design and calculations will be provided for the new light -pole foundations in accordance with CBC, ASCE 7, and MUSCO engineering criteria. Deliverables will include updated electrical plans, photometric exhibits, foundation details, and coordination with ongoing site work to ensure proper integration with utilities, grading, and adjacent improvements.
8. Revisions to the soccer field surface
The City has requested redesign of one existing synthetic turf soccer field to a natural ‑grass playing surface. This change requires a substantial reconfiguration of the field section, subgrade elevations, irrigation infrastructure, and adjacent site improvements. Because the natural ‑grass system requires a crowned field for proper drainage, the center of the field wil l be raised approximately 22 inches, with slopes transitioning uniformly to the sidelines and end lines.
The elevation increase required for the crowned natural‑grass profile will affect multiple adjacent site features. These impacts include barrier walls, which may require height adjustments, footing evaluations, wall extensions, or regrading of adjacent surfaces to maintain proper sightlines, guardrail requirements, and structural integrity relative to the new field elevations. Where barrier walls currently tie into pathways, pavements, or accessible routes, transitions will need to be regraded and redesigned to maintain stability and compliance with accessibility standards.
The raised field elevation will also impact the storm drain system, which has been previously coordinated for construction. Modifications may be required to storm drain inlets, connection points, pipe inverts, and flowline slopes to ensure proper hydraulic performance with the revised field elevations. Surface drainage patterns will be altered by the crowned profile, potentially requiring reconfiguration of conveyance paths, adjustments to swales and collection points, and updates to storm drain alignments serving the field and adjacent improvements.
If the City elects to extend the increased field elevation through the spectator stands, additional impacts will occur to the ADA ramps, walkways, landing elevations, and handrail configurations.
These changes may necessitate redesign of the accessible routes to maintain compliance with current ADA requirements.
Conversion to natural turf will also require a complete redesign of the irrigation system, including revised mainline and lateral sizing, sprinkler layout, pressure regulation, zoning, and tie ‑ins to the existing water supply. Subsurface drainage features may need to be added or modified to ensure adequate removal of excess moisture from the natural‑grass system.
April 17, 2026
Changes to the field elevations and storm drain routing may also influence drainag e patterns extending toward the playground footprint, requiring coordination with the previously revised playground grading, surfacing, and accessibility elements.
Deliverables for this scope will include updated grading plans, barrier ‑wall modifications, storm drain revisions, irrigation design plans and calculations, updated ADA ramp and accessibility layouts, construction details, and coordination with previously approved drawings and ongoing site work.
9. Electrical Redesign (Water Feature, Walkway, courts) The City has directed modifications and additions to multiple site elements after construction activities had commenced, requiring comprehensive redesign of associated electrical systems.
This added scope was not included in the original contract and req uires new electrical engineering, coordination with in ‑progress construction, and integration with existing and previously approved electrical infrastructure. The electrical redesign includes pedestrian walkways, handball and basketball courts, the interac tive water feature, and associated site improvements requiring power, lighting, and controls.
Services will include redesign of site and walkway lighting systems to accommodate revised alignments, updated grading, new program elements, and accessibility requirements. Work will address revised fixture locations, illumination levels, circuiting, conduit routing, pull box placement, grounding, and coordination with underground utilities, drainage, hardscape, and landscape improvements. Electrical load evaluations will be performed as required to confirm adequacy of existing panels or identify necessary service or panel modifications.
Electrical design for the handball and basketball courts will include integration of MUSCO sports lighting systems and associated power and control infrastructure. Services will include coordination with MUSCO, design of feeders and branch circuits, conduit routing, pull boxes, grounding systems, and panel adjustments as required, all coordinated with court foundations, pavements, storm drain relocations, irrigation revisions, and other underground improvements.
Electrical design services will also include power and control coordination for the interactive water feature, including vendor coordination, equipment power requirements, control interfaces, grounding and bonding, GFCI protection, and compliance with applicable electrical and safety codes for wet environments.
Because construction was already underway when these revisions were initiated, additional coordination will be requir ed to integrate redesigned electrical systems with installed or in‑progress work. This effort will include review of as ‑built conditions, coordination with the contractor on sequencing and constructability, resolution of conflicts, and revisions necessary to minimize demolition or rework. Deliverables for this added scope will include revised electrical plans, updated lighting layouts and schedules, conduit and wiring diagrams, electrical calculations as required, and construction documentation necessary to implement the revised electrical systems.
April 17, 2026
10. Communication Redesign
The City has directed modifications and additions to park amenities after construction activities had commenced, requiring redesign and expansion of associated communications systems.
This added scope was not included in the original contract and requires new engineering, coordination with in -progress construction, and integration with existing site infrastructure.
Communications systems impacted include underground communications pathways, pull boxes, and routing to support park -wide systems such as Wi -Fi, security cameras, controls, and network connectivity associated with walkways, courts, the water feature, and other revised site elements.
Services will include design and coordination of communications conduit alignments, junction locations, and equipment interfaces, including separation from electrical systems and coordination with civil, storm drain, irrigation, hardscape, and lighting improvements.
Coordination will be provided with the City, contractor, and system vendors to confirm connection requirements, equipment locations, power interfaces, and future expandability.
Because construction was already underway, additional coordination will be required to integrate revised communications systems with installed or in -progress work and to minimize rework. Deliverables will include revised communications plans, conduit and pathway layouts, coordination details, and construction documentation necessary to implement the communications systems.
11. Water Feature Addition
The City has directed the addition of an interactive water feature to the project after construction activities had commenced. This work was not included in the original scope and requires new design, coordination, and integration with site improvements currently under construction.
Services will include development of the water feature layout, coordination with the selected water feature supplier, and site planning to address user circulation, safety clearances, accessibility, and interface with adjacent park amenities.
Civil engineering services will include grading and drainage design to accommodate the water feature, including surface slope adjustments, collection systems, and connection to the approved storm drain or sanitary system as applicable. Utility design and coordination will include domestic water service connections utilizing the proposed lateral on -site, isolation valves, and routing to equipment locations, as well as electrical coordination for power, controls, and associated equipment. Finished surface elevations will be coordinated with adjacent pavements, play areas, and landscaping to maintain positive drainage and safe transitions.
Additional services will include coordination of concrete and structural elements associated with the water feature, such as drainage structures, and surface finishes suitable for continuous wet conditions. Coordination will be provided with the City, contractor, and specialty consultants to avoid conflicts with ongoing construction and minimize rework. Deliverables will include updated layout plans, grading and drainage sheets, utility plans, coordination details, and construction documentation necessary to implement the interactive water feature.
ASSUMPTION
Willdan assumes that the County will allow the playground equipment to be placed in the easement.
April 17, 2026
FEE
Willdan proposes the work mentioned above for a lumpsum fee of $307,585.00. Any additional task not listed here will be under a separate task order. Please see attached fee matrix for a detailed breakdown of costs associated with the scope of work outlined above.
In conclusion, Willdan’s current budget of $1,199,473.00. is proposed to be increased by $307,585 for a revised total of $1,507,058.
1. Meetings and Concepts $ 32,468.00
2. Handball Courts $ 38,352.00
3. Basketball Courts $ 33,084.00
4. Storm Drain Relocation $ 16,900.00
5. Irrigation System Redesign and Landscape Revisions $ 16,120.00
6. Playground Redesign and Expansion $ 13,374.00
7. MUSCO Lighting $ 6,096.00
8. Revisions to the soccer field surface $ 66,472.00
9. Electrical Redesign (Water Feature, Walkway, courts) $ 20,158.00
10. Communication Redesign $ 5,526.00
11. Water Feature Addition* $ 43,231.00
12. Additional Construction Support $ 15,804.00 Grand Total $ 307,585.00
Please indicate approval and authorization to proceed by either printing out and signing two originals and returning one hard copy original to our office, or by scanning one signed original and returning it by email.
Thank you for this opportunity to be of continuing service Reyes Construction . We recognize the importance of this project and are committed to realizing its timely and successful completion. Should you have any questions regarding this proposal, please contact me at (714) 393-1963 or [email protected].
Respectfully submitted, Approval and Authorization to Proceed By:
WILLDAN ENGINEERING Reyes Construction, Inc.
_______________________________
Tyrone Peter, PE Steve Leathers, PE
Director of Engineering Vice President
April 20, 2026
Date Date
17 WILLDAN ENGINEERING
Civil Design
Lead
Traffic
Design
Lead
238 231 231 178 178 190 161 161 227 184 168
1. Meetings and Concepts 16 8 8 12 40 32 48 32,468.00$
2. Handball Courts 2 4 8 12 24 8 40 40 8 24 48 38,352.00$
3. Basketball Courts 2 4 8 12 24 4 12 40 8 24 48 33,084.00$
4. Storm Drain Relocation 2 8 24 64 16,900.00$
5. Irrigation System Redesign and Landscape Revisions 2 8 16 4 20 42 16,120.00$
6. Playground Redesign and Expansion 2 4 16 8 10 12 20 13,374.00$
7. MUSCO Lighting 2 12 16 6,096.00$
8. Revisions to the soccer field surface 16 24 80 120 24 40 64 66,472.00$
9. Electrical Redesign (Water Feature, Walkway, courts) 1 40 60 20,158.00$
10. Communication Redesign 1 8 24 5,526.00$
11. Water Feature Addition* 4 8 24 8 40 80 12,500.00$ 1,875.00$ 43,231.00$ Construction Support 8 8 8 4 24 4 22 4 15,804.00$
Grand Total 58 60 84 164 132 12 52 372 106 214 354 $ 12,500 $ 1,875 307,585.00$ AMENDMENT NO. 4
SUMMARY TASK HOURS Principle PM
- Landscape
Sr.
Landscape
Architect
Asso
Landscape
Architect
Senior Plan
Checker
(Structural)
Hermosillo Park Rehabilitation, Stormwater Capture and Infiltration Project AMENDMENT NO. 04
FEE SCHEDULE
Director/
Project
Manager
Senior
Designer II
Assist
Engineer III
(Structural)
Assist
Engineer III
(Civil)
Subconsultant
Direct
Expenses
and Subs
Mark Up 15%
Amount
Senior
Designer II
(Elec/
Comm)