Engineering Core · Section 5.4 / 5.5

Proposed Interventions

Five Blue-Green Interventions (BGI) and three Grey supplements (GI) proposed under the Marilao Flood-Free Master Plan. Grey infrastructure is held below 30% of total capital to preserve the Sponge Town thesis.

BGI-01 · Blue-Green
Marilao River Linear Park + Retention Corridor
Years 2-3
Barangays
Poblacion I, Poblacion II, Abangan Norte, Abangan Sur, Tabing-Ilog, Ibayo, Saog
Indicative cost range
PHP 40M - 80M
Rationale
Activates the PD 1067 Art. 51 3-m river easement as a linear park with ~5,000 to 10,000 m3 of distributed retention along the ~2 km urban reach.
BGI-02 · Blue-Green
Saog Retention Basin (Punong Tulay / Ramcar)
Year 1
Barangays
Saog
Indicative cost range
PHP 25M - 50M
Rationale
~15,000 m3 basin sized to buffer a 3-hour peak of an Ulysses-class event (3.05 m observed at Punong Tulay, 2020).
BGI-03 · Blue-Green
Abangan Norte Retention + Green Corridor
Year 1
Barangays
Abangan Norte, Abangan Sur
Indicative cost range
PHP 20M - 40M
Rationale
~8,000 m3 retention plus green corridor to attenuate the recurrent ~1.7 m depth at Abangan Norte Town and Country.
BGI-04 · Blue-Green
Permeable Surface Program (Poblacion CBD)
Years 2-3
Barangays
Poblacion I, Poblacion II
Indicative cost range
PHP 30M - 60M
Rationale
Converts ~10 ha of hardscape to permeable pavement and bioretention in the densest built-up core (Poblacion I at 82.94% population exposure).
BGI-05 · Blue-Green
Informal Settler Protection-in-Place
Year 1
Barangays
Lambakin, Abangan Norte
Indicative cost range
PHP 50M - 100M
Rationale
Elevated platforms, on-lot drainage, and raised evacuation routes for ~500 to 800 ISF households under RA 7279 / CMP pathway.
GI-01 · Grey
MacArthur Highway Drainage Upsizing
Years 2-3
Barangays
Abangan Norte, Abangan Sur, Ibayo, Tabing-Ilog
Indicative cost range
PHP 60M - 120M
Rationale
DPWH-standard upsized box culverts and side-drain conveyance on the national lifeline cut by every major event in the historical record.
GI-02 · Grey
Lias Road Drainage Supplement
Years 2-3
Barangays
Lias
Indicative cost range
PHP 15M - 30M
Rationale
Supplemental side-drains and culvert upgrades on a secondary lifeline impassable in 5+ recent events.
GI-03 · Grey
Pump-Station Hardening at Low Points
Years 4-5
Barangays
Poblacion I, Poblacion II, Ibayo
Indicative cost range
PHP 20M - 45M
Rationale
Addresses Manila Bay tidal backflow where gravity drainage fails; requires pump-station inventory validation with LGU Engineering.

Source: Master Plan Engineering Core (Section 5) · Subsections 5.4 (Blue-Green) and 5.5 (Grey Supplements). Conceptual-scale figures subject to detailed modeling at implementation phase.