MIRADA ROAD

Along Mirada Road in Miramar, inevitable deterioration of rock slope protection (riprap) from wave action is ongoing.

2016: Coastal Commission granted two emergency permits, G-2-16-0018 for supplemental riprap boulders at toe of bank approximately 100 feet south of Medio Ave, and G-2-16-0066 for roadway shoulder revetment repairs between Magellan and Medio: County project page.

2016 July: County Sea Level Rise Adaptation Design Charrette with breakout discussion on Mirada Rd, and follow-up MCC meeting (minutes, Item 4b) where Supervisor Horsley spoke about the need to meet with property owners about forming a benefit assessment district going forward, that the long-term solution is retreat, and managed retreat won’t be paid for by the County (meaning other county taxpayers).

2017: County had initially proposed a retaining wall system and one-way traffic for Mirada Rd erosion protection, but did not pursue the project after unfavorable review by Coastal Commission staff and US Army Corps of Engineers.

2018 SMC Sea Level Rise Vulnerability Assessment Final Report includes these Mirada Rd Inundation/Erosion Hazard Maps

2020:  Public Works Director Jim Porter said at Aug 12 MCC meeting that the County stepped back from working on Mirada Rd and will be looking to the newly formed SMC Flood & Sea Level Rise Resiliency District (One Shoreline) for solutions, to protect or retreat.  This new county-wide District has a very small staff and has no current plans to take on Mirada Rd or bridge replacement.

California Coastal Commission (CCC) recent local coastal armoring decisions

No seawall to protect Coastal Trail south of Mirada Rd:
July 2019 CCC decision denied a section of seawall proposed to protect the Coastal Trail west of Casa Mira condominiums on Mirada Rd (staff report).  Surfrider argued that the Coastal Trail is not a coastal-dependent use, but can be relocated and is therefore not entitled to shoreline armoring, and that using the Coastal Trail as justification would set a terrible precedent for the rest of the state. Commissioners agreed and approved the seawall only where needed to protect the pre-Coastal-Act apartment building at 2 Mirada, but not for the Coastal Trail. When necessary, the Coastal Trail can easily be rerouted east of the condos to Mirada Rd, as all the adjacent open land south of Mirada Rd belongs to State Parks.  

Just south of Arroyo de en Medio, the existing unpermitted section of riprap around the parking lot of the 3-story apartment building is the subject of a separate CCC enforcement action.

No armoring of creek banks:  Aug 2020 CCC decision on appeal of Moss Beach bluff-top house (staff report) included prohibition of future armoring of the adjacent steep banks of Dean Creek ravine which fall under the LCP definition of coastal bluff (just as do the banks at the mouth of Arroyo de en Medio).
Deep piers & tie-back foundation for coastal hazard stability was also prohibited because it is a form of coastal armoring.  These foundations have been used in Miramar in the past, and they would interfere with managed retreat from sea level rise and erosion.

MIRADA ROAD BRIDGE

County Dept of Public Works (DPW) page for bridge replacement

The concrete arch bridge over Arroyo de en Medio Creek was built in 1917, and was closed to vehicles after completion of Hwy 1 in the late 1950’s.

A steel pedestrian bridge was installed over the top of the failing concrete bridge in 2003, which served as the Coastal Trail until abruptly closed as unsafe in July 2020.  Construction of a replacement bridge is not expected until summer 2021 at the earliest.  Construction of the Parallel Trail bike/pedestrian bridge on the east side of Hwy 1 is expected in summer 2021 with a trail from Coronado in El Granada south to the HMB city limit at Mirada/Alto Roads where it will connect with an extension of HMB’s parallel trail.  Until then, the only north/south route over Arroyo de en Medio for all users is Hwy 1.

BRIDGE TIMELINE

2001-10-09: MCC P&Z Committee comment on permit application to construct steel pedestrian bridge over the top of the failing concrete Mirada Road Bridge:  Agree it would have no impact on creek corridor or beach area and would like to ensure that no riprap is added. Encourage Granada Sanitary District to re-route the sewer line off the bridge, and County to eventually remove the arch structure to allow the creek bed to be full-sized and unobstructed.

2017/04/03:  Permit application #2-17-0289 to Coastal Commission (CCC) to construct soil nail reinforced, sculpted shotcrete walls to address the eroding shoreline at the pedestrian bridge over Arroyo de en Medio.  See 4/13/18 Sand Supply Study for project details.  Filing status incomplete and application withdrawn 6/3/20.

2018 summer: Structural engineering evaluation of bridge estimated two more years of life (oral report by DPW at MCC 8/12/20 meeting after bridge closure).

2019-03-26:  Grant application to State Parks Division of Boating and Waterways for $1,463,765 for Mirada Rd Pedestrian Bridge replacement and bank stabilization project (not funded).

2020-06-03:  Permit application submittal to Coastal Commission:  DPW asks to withdraw 2017 Permit app #2-17-0289 (soil-nail walls north & south of bridge) and submit new CDP application to include replacement of the pedestrian bridge, and hybrid armoring consisting of shotcrete walls with tieback anchors as well as rock slope protection along the northern and southern banks of Arroyo de en Medio.  These previously unreleased documents were obtained from CCC in Oct 2020:
Application cover letter & additional info 6/3/20
Sand supply study 4/13/18
Project Benefits and Alternatives Analysis 10/2/19
Geotechnical Investigation 1/10/20
65% Design Plans 1/16/20
Permit applications were also submitted to: US Army Corps of Engineers, CA Dept of Fish & Wildlife, and SF Bay Regional Water Quality Control Board.

2020-07-15:  CCC letter:  incomplete CDP App #2-20-0319 (Mirada Road Soil Nail Wall and Pedestrian Bridge Replacement).  Additional info needed, including as-built plans for the two 2016 emergency riprap projects on Mirada Rd.

2020-07-27:  Bridge closed as unsafe: press release

2020-08-10:  DPW letter provides additional info to CCC.

2020-08-12:  MCC agenda item on Mirada Rd bridge & detour (bridge condition, detour, minutes, video @17min)
None of the bridge replacement documents & correspondence were available to the public until posted here 10/6/20.

2020-09-17:  CCC letter asks for additional details and evaluation of Alternative 2 (relocate bridge to Alameda) and 4 (current location), rerouting of sewer line, and info/permits on existing riprap along the base of the creek inland from the bridge.
DPW 12/15/20 reply

2020-09-21:  Detour safety improvements on Hwy 1 completed: Reduce # lanes from 3 to 2, add K-rail & crash cushions to protect west side bike/ped detour area.

2020-10-14 & 10-28:  MCC agenda items on CDP application for bridge replacement and coastal armoring at Medio Creek:
MCC letter, slide presentation, correspondence received.

2020-12-09: MCC agenda item on bridge replacement:
County memo on Coastal Trail alignments & coastal erosion
DPW presentation on bridge replacement alternatives

2020-12-16:  DPW publishes Notice of Availability and Notice of Intent to Adopt an Initial Study / Mitigated Negative Declaration (project CEQA review). Public Comment period is 12/16/20 – 1/15/21.