Santa Ana Regional Water Quality Control Board
December 23, 2025
Christopher Nichelson
President
Milan Capital Management, Inc.
701 S. Parker Street, Suite 5200
Orange, CA 92868
([email protected])
COMMENTS ON REQUESTED ALTERATION OF STOCKPILE H TO
ACCOMMODATE TRUCK HAULING ROUTE FOR PROPOSED MABURY
RESIDENTIAL DEVELOPMENT – RIO SANTIAGO, 6145 E. SANTIAGO CANYON ROAD, ORANGE, CA (GLOBAL ID NO. T10000023109; CR SITE ID NO. 2080228) Dear Mr. Nichelson:
Santa Ana Regional Water Quality Control Board (Santa Ana Water Board) staff have reviewed Requested Alteration of Stockpile H to Accommodate Truck Hauling Route for Proposed Mabury Residential Development (Requested Alteration), dated December 10, 2025, for Rio Santiago, located at 6145 East Santiago Road in Orange (Site). The Requested Alteration was prepared on your behalf by your consultant, Verdantas Inc. (Verdantas) and submitted to the Orange County Health Care Agency (OCHCA) and the Santa Ana Water Board. This letter provides our comments on the Requested Alteration.
Proposed Scope of Work
Stockpile H, located at the Site, is requested to be altered to accommodate an on-Site haul route to the northern adjacent Mabury residential development site (Mabury site).
The Requested Alteration proposes the following activities:
• Relocation of approximately 12,765 cubic ya rds (CY) of soil from Stockpile H to two areas on the Site.
o Per an email from Mr. Nichelson, dat ed December 22, 2025, the lower ten feet of Stockpile H will not be moved or disturbed as part of the alteration. • Approximately 1,275 CY of the 12,765 CY of Stockpile H soil will be emplaced in the area depicted in olive green (Attachment 1) to provide the fill needed to widen a portion of the proposed haul route.
o The depth of the area to be filled is approximately 10 to 15 feet. o The maximum width of the area to be filled is approximately 40 to 45 feet.
Mr. Christopher Nichelson - 2 - December 23, 2025
• The remaining balance of Stockpile H soil proposed for relocation, approximately 11,490 CY, will be moved to and re-stockpiled at the area outlined in purple (Attachment 1).
• A California-licensed Professional Land Surveyor will conduct a survey of Stockpile H and the proposed soil relocation areas to provide “before and after” topographic exhibits.
• Engineering controls, as listed below, will be used to help prevent soil from migrating off-Site:
o Municipal water will be continuously applied, as needed, to disturbed soils during loading, transportation, and emplacement to mitigate airborne fugitive dust emissions
o Shaker/track plates will be installed on the Rio Santiago Site side of the proposed temporary earthen bridge to mitigate soil transfer originating from the Site to the Mabury site.
Discussion
The Mabury site, directly north of the Rio Santiago Site, requires the import of clean fill material. The Requested Alteration presents two haul route options for transporting the clean fill material to the Mabury site: Option 1 will transport the material via city streets through the current Mabury Ranch residential community north of the Mabury site; Option 2 will transport the material through the Rio Santiago Site and onto the Mabury site by way of a temporary earthen bridge across Santiago Creek. The proposed earthen bridge has been permitted by the United States Army Corps of Engineers. The bridge will be constructed from clean fill material excavated from the Mabury site, per Ms. Diane Scioli, Construction Manager for Milan Capital Management, Inc. As stated in the Requested Alteration, Option 2 is the preferred haul route as it will eliminate approximately 200 daily dump truck trips through the Mabury Ranch residential community over the course of approximately four to six months.
The Santa Ana Water Board prefers that imported clean fill material be used for the haul route area that needs to be filled. However, the use of material from Stockpile H, as described above, is acceptable to fill in the area needed for the on-Site haul route.
Regardless of where the fill material is sourced from, the Santa Ana Water Board may require sampling of the haul route fill area in the future, if warranted.
Comments
We concur with the proposed scope of work, provided that the following comments are addressed:
1. Ensure that no visible dust migrati on is observed during stockpile grading and relocation activities, including during non-working hours. Refer to Department of Toxic Substances Control (DTSC)’s Community Air Monitoring Plan Guidance and Mr. Christopher Nichelson - 3 - December 23, 2025
South Coast Air Quality Management District (SCAQMD) Rule 1466, as needed, for protocols to minimize and address fugitive dust emissions during field work for the Stockpile H alteration.
2. Ensure that appropriate er osion prevention controls are used to prevent material from Stockpile H from migrating to areas outside of the Stockpile H footprint or the approved relocation areas.
3. Ensure that no other on-Site stockpile s are disturbed or impacted during alteration and relocation activities for Stockpile H.
4. If imported clean fill material is used for the haul route fill area, provide the source facility name and address to the Santa Ana Water Board prior to the emplacement of the fill material.
If you have any questions, please contact Pamela Ybarra, Senior Water Resource Control Engineer at (951) 782-4990 or [email protected]. You may also contact me at (951) 782-9475 or [email protected].
Sincerely,
Alan Kuoch, PG
Groundwater Protection Branch Manager
Attachment 1: Haul Route Exhibit C
cc: Diane Scioli – Milan
Michael Priestaf – Verdantas
Robin Ferber – Verdantas
Darwin Cheng – OCHCA
Shyamala Rajagopal – OCHCA
Soheil Afshari – OCHCA
Dan Weerasekera – OCHCA
Tamara Escobedo – OCHCA
Christopher Cash – City of Orange
M
N
O
AREA TO BE FILLED
TO CREATE HAUL ROUTE
AREA WHERE A PORTION
OF STOCKPILE H WILL BE
MOVED TO
-C